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1. www circuitcellar com Online Training for Microchip PIC Microcontrollers 8 Week Online Course Learn at your own pace with confidence Uses EasyPIC5 Development Board See Webpage for Course Contents Schedule and what Former Students say Course is loaded with Flash Videos and Lots of Hands on programming exercises 4 week grace period to finish First commercial whole pd compression optimizer ple versions Global optimizer Simple to use IDE Multiple platform support CIRCUIT CELLAR dua Free Training Work Smart Get Logic Introducing the Logic Analyzer Remastered e 8 input 24MHz USB e SPI I2C Serial Decode All Aluminum e Mouse over timing data e Snap to edge markers 149 Also find Logic on geni com a or google logic analyzer PA 5379 0EM 60 Low Cost Controllers with TFT ADC DAC UARTS 300 I Os solenoid relays Compact Flash LCD Ethernet USB motion control Custom board design Save time and money m VISA MasterCard Issue 217 August 2008 89 PHN IBL phyCORE Baa use discount code es Viele a COTS Siete Eget Compeieri ke m shorten tinr in markrt E piece developreeet costs Command 4ine starting at 50 m fune Grans IDE w Adv Debugger starting at 350 FLL sni ies m Windows Esibeddrd CE Compiler Features include and Linus 1 8 18 and 32 in
2. CO O Across 4 Unit of magnetic flux 6 A list of a blogger s favorite blogs 10 A station for a laptop I1 Gas Electric 13 Rotating part of a magnetic circuit 17 An integrated circuit with two or more processors for improved performance 19 Prevents overcurrent 20 Magnifier The answers are available at www circuitcellar com crossword www circuitcellar com k N NO i O Co on Down 1 A chain of writings about a single subject in a newsgroup or forum 2 1O 3 Bolis fireball 5 Text message Back at keyboard 7 To start an app 8 A tool that converts data into code 2 THz 12 A touchscreen coated with a substance that conducts continuous electrical current across the sensor 14 A cellular tower that provides phone service to a small area 15 A circuit board with predrilled holes in the form of a grid 16 To convert something like a text file into web content 18 Electronic memory that isn t erased when power is removed CIRCUIT CELLAR Issue 217 August 2008 93 INDEX OF ADVERTISERS The Index of Advertisers with links to their web sites is located at www circuitcellar com under the current issue Page Page Page Page 91 AAG Electronica LLC 91 FlexiPanel Ltd 90 Mach Design Services LLC 88 Reach Technology Inc 29 AP Circuits 77 Grid Connect Inc 87 90 Micro Digital Inc 39 Renesas Technology 92 All Electronics Corp 88 Hags
3. Flash Program Memory USB Type 8 bit Up to 128 Kbytes 20 80 Device 16 bit Up to 256 Kbytes 64 100 Device Embedded Host Dual Role OTG 32 bit Up to 512 Kbytes 64 100 Device Embedded Host Dual Role OTG E73 O Mrcnocure August 2008 Embedded Development 14 The DMX Portal Lighting Control Made Simple p 14 Obtain Lighting Control Via Ethernet Matt Ernst Third Place WiZnet iEthernet Design Contest 2007 INTELLIGENT ENERGY SOLUTIONS Electric Vehicle Inverter Design Build A System For Powering AC Induction Motors Dan Hall Tristan Kasmer Doug Krahn Adam Mcintyre amp Dena Ponech Subcategory Winner Microchip 2007 Design Contest 7e D MSM DEV1I2140R 4 Electric Vehicle Inverter p 22 44 PSoC Design Techniques Part 2 Add DSP Effects A User Interface And More Chris Paiano A Two Stage Bootloader p 34 40 ABOVE THE GROUND PLANE 60 THE DARKER SIDE IR Proximity Sensing Direct Digital Synthesis 101 Ed Nisley Robert Lacoste FROM THE BENCH 78 SILICON UPDATE Water War Prevention Icy Hot An MCU Based Monitor For A Communal Well The Soft Core Concept FPGAs And You Jeff Bachiochi Tom Cantrell 4 TASK MANAGER 94 INDEX OF ADVERTISERS Hone Your Embedded Development Skills September Preview 96 PRIORITY INTERRUPT J Abate 8 NEW PRODUCT NEWS A Reactive Necessity edited by John Gorsky Steve Ciarcia 93 CROSSWORD 6 Issue 217 August 2008 CIRCUIT CELLAR www circuitcellar com
4. See our Memory from 179 0 d Uitechiools www tech tools com 972 272 9392 v sales tech tools com NN al Tern Fa Tal aii migra i d registeren t lt Ta ZT ir ni B U s Pad v hs leacnnolooy Ine Propeller Proto Board L Parallax s Propeller Proto Board is a low cost high project in the Parallax 2008 quality solution for permanent projects using the Propeller Design Contest Propeller chip The Propeller Proto Board is now available in for a chance to win 4000 in Serial and USB versions For projects which do not need the USB cash and prizes interface after programming we recommend purchasing the Propeller Proto Board Serial Version and Prop Plug not pictured 32201 Projects will be judged on the 24 95 as the reusability of the Prop Plug reduces overall cost when following factors Propeller Design programming multiple boards Appropriateness Originality Professionalism and Practicality 2008 Propeller Design Contest 4000 in cash and m prizes available Key Specifications of the Propeller Proto Boards e Power requirements 6 9 VDC 300 mA 1 5A Prize money distribution current requirement depends on application e First Place Prize 2 000 Dimensions 3 x 4 in 7 62 x 10 16 cm e Second Place Prize 1 000 Operating temp range Industrial 40 C 85 C Third Place Prize 700 3 Honorable Mention 100 ea Order the optional Accessory Kit which include
5. Electronic Design 2001 http electronicdesign com Articles Index cfm ArticleID 4346 G Priest Dorman Chording Key board http chorder cs vassar edu Vishay Semiconductors optical sensor information www vishay com optical sensors SOURCES HSDL 9100 Analog output reflective sensor Avago Technologies n e Agilent n e HP www avagotech com products parametric ir_sensors proximity_sensors SwitcherCAD Spice III simulator Linear Technology Corp www linear com designtools software switchercad jsp GP2YOAHOIKOF High precision dis placement sensor Sharp Electronics Corp www sharpsma com BPV23NF Infrared photodiode Vishay Semiconductors www vishay com Issue 217 August 2008 43 FEATURE ARTICLE by Chris Paiano PSoC Design Techniques Part 2 Add DSP Effects A User Interface And More Chris continues explaining PSoC design techniques by describing his eight channel mixer project This month he covers how to enhance the single chip design with DSP effects an intercom mode a user interface soeech and permanent setting memory Last month I demonstrated some advanced analog design techniques in the form of a PSoC eight channel mixer with adjustment knobs In this article I will explain how to further enhance the single chip design with digital sig nal processing DSP effects an inter com mode a user interface speech and permanent setting memory ADD DSP EFFECTS Suppo
6. S 50 kHz 65 536 Thus any frequency from 0 76 Hz to NW U 10 000 20 000 30 000 40 000 50 000 60 000 close to 20 kHz with a frequency step of 0 76 Hz For example just choose W 9 328 and you get a frequency of 7 116 69 Hz That s far closer to the 7 117 Hz target isn t it The magical trick comes from the fact that a DDS allows drastically finer frequency steps because the phase increment is not necessarily a sub multiple of the period At this point I can t resist telling you about a great simulation tool for mixed signal designs Labcenter Electronics s Proteus tool suite includes tools for schematic entry Spice simulation and PCB design It also provides an impres sive simulator named virtual system modeling VSM as an option With VSM you can simulate the code running on a microcontroller like any firmware sim ulator and the electronic circuits like any Spice like simulator but you can simulate both simultaneously Take another look at Photo 1 A virtual scope enabled me to verify the DDS signals Spectrum log scale N 16 P 10 B 16 W 5 166 N IW 10 000 20 000 30 000 40 000 50 000 60 000 Spectrum log scale N 16 P 10 B 16 W 5 167 L Figure 8 Here I m illustrating spurious phase truncation The left column is a DDS with 12 bits effectively used as a look up table address The right is with only 10 bits The spurious spectrum is far more numerous and powerful in t
7. pdf Se 10 DLP Design DLP USB245M User Manual 2002 www ftdichip com Documents DataSheets DLP dlp usb 245m13 pdf 11 Future Technology Devices International D2 XX Pro grammer s Guide 2005 ftp ftp efo ru pub ftdichip Documents D2XXPG31 pdf 12 Microchip Technology Inc PIC18F2525 2620 4525 4620 Data Sheet 28 40 44 Pin Enhanced Flash Microcontrollers with 10 Bit A D and nanoWatt Technology DS39626C 2007 wwl microchip com downloads en DeviceDoc 39626C pdf Ao add valia HH OC Coase od ro Pits Une TOH pD HUE S nS Service Free TED DIES DB nO 6 nL Z Free Hp EOR sees y Poni ors tant tL High Quality Competitive Price zl g Pr ar Pe T YB G c AR E S S A S L www circuitcellar com 7 CIRCUIT CELLAR 13 MCP2515 Stand Alone CAN Controller with SPI Interface DS21801D 2005 ww1 microchip com downloads en DeviceDoc 21801d pdf 14 MCP2551 High Speed CAN Transceiver DS21667E 2007 wwl microchip com downloads en DeviceDoc 21667E pdf 15 Robert Bosch CAN Specification Version 2 0 D 70442 1991 www semiconductors bosch de pdf can2spec pdf RESOURCE B Bose Modern Power Electronics and AC Drives Pren tice Hall Upper Saddle River NJ 2002 SOURCES DLP USB232M G Integrated module and FT232BL USB UART Future Technology Devices International www ftdichip com MC 1 Development board
8. Full DRC included on all orders High Quality protolypes al LOW cost s Simply send your layout files and order online TollFree USA 1877 3908541 www pcb pool com Email salesi amp pcb pool com LXX sr agi gh HW oad ur RSK 4p cons rcs NEN a 72 lssue 217 August 2008 CIRCUIT CELLAR Descriptor size in bytes DEVICE descriptor type USB version Class subclass Protocol packet size USB Vendor ID USB Product ID Device release Manufacturer string index Product string index Serial Number of configurations BGD 2 0 CDC none none Endpoint 0 BCD 1 0 number string index firmware on other example code that transfers data using bulk or interrupt transfers Any complete example firmware includes code for returning descriptors and responding to other control transfers and events on the bus At the device bulk and interrupt transfers are identical The only differ ence is how the host schedules the transfers DUTIES OF FIRMWARE Refer to the USB Crash Course sidebar for a quick review of USB basics USB CDC firmware for a generic COM port device performs several tasks During enumeration the firmware responds to requests for descriptors that identify the device s CDC function The device receives COM port data following OUT token packets addressed to the bulk OUT endpoint and sends COM port data or NAK in response to IN token packets addressed to the bulk IN endpoin
9. Gate driver assembly module block diagram IGBT Module 2 trrRip Adjust D1 D2 1 Ver Detect 4 Vec 15 8 V w buffer Optocoupler 3 Voc 15 8V 12 Ver 0 Bi Ve 8 2 Figure 2 These are gate driver board circuit connections to one IGBT Bottom transistor connections are Issue 217 August 2008 23 Photo 2 The motor control board is shown here We based our design on a Microchip Technology dsPIC MC1 motor controller board control of load currents can be obtained As the current pass ing through the IGBT increases the amount of gate current must also increase to keep the IGBT saturated The gate driv er assemblies we used for our inverter project are capable of driving an IGBT that can switch up to 400 A The gate cur rent required to control this amount of current is approximate ly 5 A DC The gate driver assembly also provides optical isola tion of control signals via high speed open collector optocou plers that protect up to 2 500 VRMS This ensures that the control signals pins 13 and 14 and high voltage signals are BASIC programmable Embedded Module Flash Disk EEPROM Real time Glock 100BaseT Ethernet Port Wi Fi well insulated from one another thus protecting the micro controller that is producing the inverter drive logic CONTROL BOARD The inverter s control board is primarily a stripped down variant of the Microchip MC 1 development board see Photo 2 9 An alternate versio
10. Lr SuperH Flash Microcontroller SuperH reaches speeds up to 160MHz Superscalar performance high speed on chip FLASH memory access and much more No 1 supplier of microcontrollers in the world proudly presents the SuperH Family of devices SuperH devices equipped with the 5H 24 core offer superscalar performance at speeds of 160MHBHz allowing high speed access to on chip FLASH memory and up to 200MHz CPU performance ROMless devices Enhanced features that include on board Floating Point Unit FPU Multiply Accumulate Unit MAC High Speed Barrel Shifter and advanced addressing modes deliver DSP like performance in RISC style architecture without the complicated programming associated with a DSP engine The SuperH RISC engine and the SH 2A core are establishing new performance standards in the industry and are ideal for systems that demand real time high precision control and require a combination of high performance CPU with high speed flash SuperH MCU Lineup H7206 apaMHz Th U Devices with USB E Devices with Ethernet SMCU Get Started Today Register to qualify for a SuperH MCU Kit www america renesas com ReachSH d RenesasTechnology Corp HHZZitqg aes nat munt an acard FPU Superscalar Performance Two instructions are executed per cycle at 160MHz World s fastest embedded FLASH with 12 5na read access tima Fast Real Time Control Hiagister Bank architecture
11. The RS 485 XLR add on board is a simple PCB that contains an RS 485 interface IC to translate the 5 V CMOS output of the PIC18F4620 to a differen tial output meeting the RS 485 fault tol erance specifications see Figure 4 This board also contains a five pin XLR con nector defined by the DMX512 A speci fication as the proper connector for DMX interfaces and eight tactile switches I used to debug the trigger functionality of the DMX portal The final board is the WIZnet PGC PGD GND ICSP VCC K BAV20W 7 F Pais 10K 3 O O O O O O ajajaj ICS ICSP and Reset MCLR IS Port A PORTA To WIZ810MJ Dev Board nW5100 INT BAV20W 7 F RAO ANO RA1 AN1 RAZ AN2 RAS ANS RA4 PGD RAS AN4 PGC RBO INTO RBT INT1 RBZ INT2 PORTA6 To WIZ810MJ Dev Board 9 DMX Serial Out ABS and DMX Expansion Board Tq LU IO Part B 16 Issue 217 August 2008 RB4 RB5 RCO RC1 RC2 19 DMX Trigg DMX Trigg DMX Trigg DMX Trigg DMX Trigg DMX Trigg DMX Trigg 30 DMX Trigg REQ RE1 RE2 0 0 D DDD 0 VSS VSS To DMX Expansion Board WIZ810MJ evaluation board which contains the W5100 hard wired TCP IP stack IC The board handles all of the low level details of the UDP Ethernet interface for the DMX Portal It also provides the passive components and the RJ 45 connector required for the Ethernet interface Data is transferred to the microcontroller through the SPI port rather than the parallel inte
12. HE ooo ee a RR or TIPP See O ee dA B eS 8 8 g PRB E oe LIII R T uc oe oe NT THERE a EN EEZII a5 uwrbEbnoob0DD4 EDD ee i 8 6 6 CL am GOGO GG a r TT do 255 amp o RR ace rs GOGO PD m D G o n G e 8 6 ELE goo d gg matig aa PP ee ee P a LET ILE a CEE bee ge Beb ea pe ee ee ERE a ee TERI T on gF IIILIITUIPLPDTDOPPCDPPTITLDCIITIILI o ed I DESSERT LRR R e GG B B E E E EID EDEGEITEEEDI ITIEEI IYILE L KR EEEE EMM GB 0P R 06 R KR L IIFP T3 1 2 11 1 122 RDO eee bee ee ee wed e RE 60 WG DG DG TED dR RER E KR kl LS SEEPS PERSO TCE CSOT eS E igi FPE p p o ee ee N Ie SG 0 98 PRPC R BBB GRE BBB B BB E P i ee E E EW EP NTM N d C h SG BB PSP PRPS PRESSE Ee eee o 7o abbbb t tt tek t HM TTHPPITITTITEMPTTEMTTITCEM 6 mu ao BE SPR SSP WR BR RR RRR E ZJIILIIIPIIIDLIIIILIIIIZILLILIII 32212 or USB 32812 online at http www N parallax com or call toll free 888 512 1024 VAN FU Mon Fri 7a m 5p m PDT www parallax com Propeller Parallax and the Parallax logo are trademarks of Parallax Inc Order the Propeller Proto Board Serial
13. This time you are energy DUEL WIMP z Oh No Not again i N Pv EE bipes A When T will the boss of e dal My ho duty 3 Be HIM hard siad rifle feeds I will show you fear ina S handful of dust Have a taste of pd Even tha i smallest of batteries Don t do this E are powerful when you know f Loan fo ma p how fo make the most 4 Learn how to combine the AVR microcontrollers high performance with the lowest possible power consumption on www atmel com avrman CO DOT Almas Gorperuiicri AP ween d Psi tine Seed PA cnet may bu pice su tan MEC Hm nit nim TT erre Br dT dTa HTP 9 Mykle Wood NEW PRODUCT NEWS MMU SUPPORT ADDED TO ARM DEBUGGER Crossware a leading embedded software tools develop er has added support for the ARM9 memory management unit MMU and fast context switch extension FCSE to its ARM Development Suite This enables developers to rapidly exploit the advanced memory management fea tures of ARM chips such as the Atmel AT91SAM9263 and AT91RM9200 microcontrollers Full debugging is possible when the MMU is enabled even when complex virtual to physical memory transla tion is used The debugger understands the memory address translation process and can determine which Edited by John Gorsky Visit www circuitcellar com npn for more New Product News physical memory is being used for different virtual addresses Full debugging is also possible when the FCSE is
14. ered or green applications The LTC2935 has three binary inputs that allow the selection of one of eight integrated reset thresholds from 3 3 down to 2 25 V in 150 mV increments The device s internal precision attenu ators allow the part to maintain only 500 nA of supply current and accuracy The LTC2934 allows an external resis tive divider to finely set the reset threshold anywhere from 1 6 to 6 V The reset thresholds in both devices are 1 5 accurate over temperature which helps to minimize supply overdesign An early warning of a threatening low voltage condition is provided via a power fail output The supervisory circuits monitor V and pull the reset output low if the supply voltage drops below the configured reset threshold The LTC2934 includes 8 Issue 217 August 2008 CIRCUIT CELLAR two reset timeout periods of 15 or 200 ms settable via a time out selection pin while the LTC2935 offers a fixed 200 ms timeout The LTC2934 starts at 1 15 each and the LTC2935 costs 1 22 each in 1 000 piece quantities They are also available today in production quantities Linear Technology Corp www linear com LTC2935 www circuitcellar com NEW PRODUCT NEWS NATIVE HARDWARE DEBUG AND C COMPILER SUPPORT FOR PIC24 MCUs AND dsPIC33F DSCs Embedded Workbench for dsPIC DSC PIC24 now supports native hardware level debugging through the Microchip Technology MPLAB REAL ICE in circuit emulator system IAR Sys
15. He reintroduces you to direct digital synthesis DDS by covering the topics of DDS theory firmware implementation and chip based solu tions p 60 Tom Cantrell wraps up this issue with an interesting article about soft core technology Does it make sense for your current applica tion Before you answer this question check out what Tom has to say about the ARM Cortex M1 and FPGA chips p 78 Happy embedded developing Cac cjQcircuitcellar com Issue 217 August 2008 CIRCUIT CELLAR CIRCUIT CELLAR THE MAGAZINE FOR COMPUTER APPLICATIONS CHIEF FINANCIAL OFFICER Jeannette Ciarcia MEDIA CONSULTANT Dan Rodrigues CUSTOMER SERVICE Debbie Lavoie CONTROLLER Jeff Yanco ART DIRECTOR KC Prescott GRAPHIC DESIGNERS Grace Chen Carey Penney STAFF ENGINEER John Gorsky FOUNDER EDITORIAL DIRECTOR Steve Ciarcia MANAGING EDITOR C J Abate WEST COAST EDITOR Tom Cantrell CONTRIBUTING EDITORS Jeff Bachiochi Ingo Cyliax Robert Lacoste George Martin Ed Nisley NEW PRODUCTS EDITOR John Gorsky PROJECT EDITORS Gary Bodley Ken Davidson David Tweed ASSOCIATE EDITOR Jesse Smolin ADVERTISING 860 875 2199 Fax 860 871 0411 www circuitcellar com advertise PUBLISHER Sean Donnelly Direct 860 872 3064 Cell 860 930 4326 E mail sean circuitcellar com ADVERTISING REPRESENTATIVE Shannon Barraclough Direct 860 872 3064 E mail shannon circuitcellar com ADVERTISING COORDINATOR
16. I yearn for a simpler time In the old days absent the modern arsenal of simulators emulators and debuggers designers often used judiciously placed PRINTF statements to get under the hood In the hands of an expert PRINTF can be surprisingly effective when it comes to finding and fixing hardware and software bugs Thanks to Micrium PRINTF lives albeit on steroids and gussied up for the PC screen see Photo 1 As I see it uC Probe has three things going for it First like PRINTF pC Probe is simple and relatively nonintrusive You just add a few lines of code to your embedded application to exchange data with n C Probe software running on the PC which in turn references the symbol table out put by your software toolchain Virtually any embedded design is supported with connection options including RS 232 Ethernet and JTAG Second is the fact uC Probe will work today and down the road with any target processor i e standard chips FPGA soft cores DSPs and more That means you can spread the cost of uC Probe across multiple chips and projects which is good because at 995 it isn t a give away Fortunately as with all the other Micrium soft ware there is a free 30 day evaluation version you can try before you buy The clincher is that uC Probe is fun thanks to the abili ty to map a symbol value to an icon or graphic on the screen Wouldn t you rather see a screen full of lights dials thermometers or pictures than the typi
17. The OmniFlash controller comes preloaded with Linux and our development kit includes all the tools you need to get your project up and running fast Out of the box kernel support for USB mass storage and 802 11b wireless along with a fully integrated Clock Calendar puts the OmniFlash ahead of the competition Call 530 297 6073 Email sales jkmicro com On the web at wwW jkmicro com JK microsystems 66 Issue 217 August 2008 purpose microcontroller or DSP is often an effective solution for signal CIRCUIT CELLAR oscilloscope or spectrum analyzer to the output click run and you have the simulated output on the display Impressive generation Imagine that you are using a small microcontroller i e a n CIRCUIT CELLAR an Searchable Archives on CD ROM CD ROM 12 2007 Issues 198 209 CD ROM 11 2006 Issues 186 197 CD ROM 10 2005 Issues 174 185 CD ROM 9 2004 Issues 162 173 Order Online www circuitcellar com or call 860 875 2199 www circuitcellar com Microchip Technology PIC16F629A clocked at 20 MHz and you need to generate a 7 117 Hz signal either sine or square This is just an example of course but real life applications can include DTMF generation data rate generation and similar problems The first idea that you a firmware developer will have will be to use the on chip timer Just configure a timer to count processor cycles 5 MHz maxi mum on this PIC variant and t
18. The header func tional descriptor names the version of the CDC specification the interface complies with The abstract control model descriptor specifies what class specific requests and notifications the device supports More on those later The union functional descriptor iden tifies the interfaces that belong to the CDC function which are typically the communication interface plus a data interface The call management func tional descriptor tells how the device manages calls Because a generic COM port device has no calls to handle the descriptor says the device doesn t han dle call management An interrupt endpoint sends status notifications to the host The end point descriptor provides the end point s number direction and wMax PacketSize The data interface is responsible for sending and receiving the COM port data The interface descriptor tells the host that the interface has two bulk endpoints one to carry data to the host and one to carry data from the host Listing 3 Each endpoint has an endpoint descriptor After retrieving the descriptors from the device and assigning the CDC driver the host polls the bulk IN end point for COM port data and polls the interrupt IN endpoint for notification data An endpoint with no data to send returns NAK in response to received IN token packets When sending COM port data to the host a device indicates the end of a transfer by sending a short packet Iss
19. UART bridge chips include MosChip Semiconductor Prolific Technology and Silicon Laboratories The device I ll describe takes a dif ferent approach The design doesn t require a specific vendor s USB con troller or driver The device can use a general purpose microcontroller with an embedded USB controller or a CPU that interfaces to an external USB con troller The USB port can be full or high speed Device firmware manages USB communications and whatever other tasks the device is responsible for Instead of a vendor specific driver the PC uses the USB communication devices class CDC driver included with Windows and other operating systems For Windows an INF file matches the driver to the device Several microcontroller vendors Listing 1 The device descriptor names the communication devices class CDC Device descriptor rom USB DEV DSC device dsc 0x12 0x01 0x0200 0x02 0x00 0x00 0x08 US US Z 0x9060 0x0100 0x00 0x00 0x01 0x01 Max provide example firmware for USB vir tual COM ports The chips include Atmel s AT89C5131 Microchip Tech nology s PIC18F4550 and NXP Semi conductors s LPX214x These examples are good starting points for projects If you don t have CDC example code for your CPU you can base your Ta Intarnet pioneers with 15 years experience Instant online Quotations amp Ordering From Singlesided fo layers ML lecdtimes trom 48 hrs
20. as a concatenation of three sepa rate DSP executable programs DXE fields The first is our INIT block that performs two functions It provides a place in the EEPROM to store a point er to the current application image and it sets up the environment a non default reset vector value in which the second stage boot kernel runs see Figure 2 www circuitcellar com Figure 3 shows the details of the EEPROM layout As a result of the space taken up by various data struc tures within the loader file the code of our INIT block begins at address 0x00018 The first thing located here must be an executable instruction so we place a jump instruction here 2 bytes that jumps past the next 4 bytes which is where we re going to store our application pointer Therefore the pointer starts at address 0x0001A decimal 26 The code following the pointer sets the Blackfin reset vector to the code memory address where l 0x2000E l 0x2000A Header IGNORE 0x20000 Empty space U U U U U U 3 U Block Third DXE Application code and data many blocks Second DXE Boot kernel one block 2 uc D 2 LL x lt E z 2 E o E o sul o 5l 2 c D i E e o C He First DXE INIT File two blocks 0x0001A 0x00018 0x0000E 0x0000A 0x00000 Length of third DXE for file the boot kernel will load and run and then returns to the Boot ROM The boot kernel is bas
21. changing its behavior to your exact specifications By mastering this technology you can develop your own chips that run at blazing speeds as well as design com plex systems that would be impossible with discrete TTL chips The MACH64 kit is two kits in one It is a complete Lattice ispMACH 4064 series development kit with a built in programmer which supports external targets as well It is also a powerful educational kit that teaches CPLD technology and programming from the ground up applicable to any CPLD The kit comes complete with everything you need to experiment design and program with CPLDs The 250 plus page manual starts off with the technology of CPLDs and then eases you into the ABEL language used to program CPLDs The numerous challenging hands on projects include basic logic gates counters state machines ALU 12 Issue 217 August 2008 CIRCUIT CELLAR design audio generation NTSC and VGA video genera tion and much more Everything you need to build all of the labs is included in the kit along with extra parts for your own creations resistors capacitors LEDs transistors diodes and more Design your own chips The MACH64 kit costs 159 95 Nurve Networks www nurve net www circuitcellar com NEW PRODUCT NEWS HIGH SPEED 870 nm INFRARED EMITTER WITH WIDE VIEWING ANGLE The TSFF5510 wide viewing angle infrared emitter with its uniquely designed lens has a viewing angle of 38 which enab
22. duces the rotating magnetic field can be controlled by a PWM algorithm that directly influences the speed of the rotating field and the output RPM of the rotor We used a PWM technique known as space vector modulation POWER INVERTER Powerex CM400DU 12F insulated gate bipolar transistor IGBT modules and their companion BG2B gate driver cir cuits provide a relatively low cost method for generating three phase AC power from DC power The DC power from the EV battery pack is converted to three phase AC to drive an AC induction motor We configured each phase of the IGBT module design with RCD snubber protection see Figure 1 2 The gate driver circuit can be seen in the appli cation note for the BG2B universal gate drive board from Powerex using two VLA106 15242 DC DC converters and two VLA503 01 gate drivers The gate driver boards are recommended by Powerex for use with the dual IGBT mod ules and provide 2 500 VRMS of control signal isolation via high speed optocouplers and desaturation detection to pre vent short circuit conditions on the IGBTs The CM400DU 12F modules are rated with a collector emitter voltage of 600 V and a continuous emitter current of 400 A with a peak rating of 800 A The modules are able to provide switching speeds of up to 30 kHz we used 20 kHz The fre quency range promotes efficient operation of the spatial vec tor modulation SVM algorithms used to drive the IGBTs and bring the switching noise out o
23. ductor y axis you would measure no potential As an external magnetic field increases through the conductor z axis the current through the con ductor would be forced off center and a potential would be measured across it A Hall sensor is designed to measure Figure 4 This Hall effect device uses a bridge sensor and associated circuitry to indicate the presence of a magnetic field greater than 40 G This is independent of the polarity Source Allegro MicroSystems Inc www allegromicro com en Products Part_Numbers 3213 3213 pdf CIRCUIT CELLAR www circuitcellar com HOLTEK wwii holtek com Imaginative Solutions Flexible large capacity and easy upgradeable intelligent controllers Holtek s HT48FxxE and HT46F4xE series with their internal 8 bit RISC core now provide customers with a wide and flexible range of devices for a huge variety of applications These devices with their large memory capacities and comprehensive functions can be used in all kinds of home appliances Additionally using Holtek s unique ISP easy re programming is provided for without device removal allowing for easy product upgrades CCC eC 10 pin MCU USB MCU Dual Slope MCU EEPROM Management TinyPower MCU Flash MCU UART MCU Audio MCU Phone MCU Wide operating voltage 2 2V 5 5V Data retention gt 10 Years Industrial specification 40 85 C Excellent noise immunity and ESD protection 9 Flash Memory can be
24. on a local level might be an ini tial necessity regional nation al and even global resolutions might better promote unity The Earth s resources do not respect our concocted territorial boundaries Do we have the rights to water coal or any other resource under our feet What about when a resource just pass es through e g a river We must respect the planet and our neighbors and we should be willing to compro mise in order to avoid major conflicts Unfortunately some people don t think this way As a result it may not be long until a gallon of water costs as much as a gallon of oil Only time will tell I do know how ever that during the next few years engineers like us will be tasked with developing new systems to facilitate better water management delivery filtration and monitoring I recently used 52 Issue 217 August 2008 Brine tank Water softener water As urban sprawl increases more rural homesteaders are tied together by local community wells and even private single home water systems While a private system might be outside the jurisdiction of town regulations I think it s safe to say that no one wants bad tasting smelly or toxic drinking water As the landscape changes we want to be assured that our water supply has not been compro mised Periodic water test ing relieves these concerns Once we find that our underground aquifer is not being polluted our attention shifts f
25. the torque and flux loops are passed a set value from the velocity loop and execute the appropriate controls The feedback loop signals for the torque and flux loop are generated by the Hall effect cur rent sensors on i and i and the velocity demand feedback is given by the encoder see Figure 4 We elected not to use the velocity control loop for accel eration of the motor The gas pedal of an internal combus tion car sets acceleration but does not set the speed Because the acceleration of a motor is directly proportional to the torque we passed the input demand value from the gas pedal directly to the torque control loop Luckily SVM provided us with the isolated control over the torque that gives the end user a more realistic feeling gas pedal ALTERING MOTOR CONTROL PARAMETERS It is important that you are familiar with the dsPIC assem bly language so you can make changes to the motor control software but expertise is not necessary The SVM portion of the software is handled as a black box This means that you do not need to know exactly how it works If you wish to alter the black box further documentation is avail DLP USB232 M G integrated module featuring FTDI s FT232BL second generation USB UART This module was an appropri ate choice for development because it can be plugged into a standard 24 pin 0 6t wide DIP socket that is mounted on our daughter board and it could be moved easily to another board if req
26. which is not easy to do especially if you need a fine resolution The DDS architecture is an improvement on this original design see Figure 2 Rather than add one to the table look up address counter at each clock pulse like the counter did in the previous example a DDS uses an N bit long phase register and adds a fixed phase increment W at each clock pulse to this register N can be quite high e g 32 or 48 bits so only the most significant bits of the phase Binary counter FCLOCK register are used to select a value from the phase to amplitude look up table which is usually nothing more than a ROM preprogrammed with a sine waveform Assume that you are using the P most significant bits as an address Then the output of the look up table is routed to a DAC And of course the analog signal finally goes through a low pass filter which is called a reconstruction filter You will understand why in a minute How does it work If the phase increment W is set to one you will need 2N clock pulses to go through all of the values of the look up table One sine period will be generated on the Foyr output each 2N clock pulses exactly like the aforementioned counter based architecture If W is 2 it will be twice as fast and the output Low pass filter Figure 1 The most basic digital signal generator is built with a simple binary counter Its output sequentially addresses the rows of a memory which
27. which is the maximum number of data bytes the endpoint can send or receive in a transaction Each USB transfer consists of one or more transactions that can carry data to or from an endpoint A transaction begins with a token packet that specifies an endpoint number and direction An IN token packet requests a data packet from the endpoint An OUT token packet precedes a data packet from the host In addition to data each data packet contains error checking bits and a packet ID PID with a data sequencing value Many transactions also have a handshake packet where the receiver of the data reports success or failure of the transaction USB supports four transfer types control bulk interrupt and isochronous In a control transfer the host sends a defined request to the device The host uses control transfers after detecting an attached device to request a series of data structures called descriptors from the device The descriptors provide informa tion about the device s capabilities and help the host decide what driver to assign to the device A class specification or vendor can also define requests Control transfers have up to three stages Setup Data optional and Status The Setup stage contains the request The Data stage contains data from the host or device depending on the request The Status stage contains informa tion about the success of the transfer The other transfer types don t have defined stages Instead higher level
28. 0 model Curent sensors error T input i ah ca ca Speed Figure 4 This is a block diagram of a PID control loop from Microchip Technology s application note AN908 index of 0 79 both in the linear range This results in a maximum line to line voltage that is almost equal to Y This result is possibly the greatest advantage of SVM because the torque that is generated by the motor is higher than any other PWM technique This provides supreme dynamic response of the motor PID TUNING There are abundant sources of material available on the Internet and in libraries all around the world that discuss in great detail the methods for tuning proportional inte gral and derivative PID control loops Therefore it is not necessary to discuss such things here but it may be helpful to present some details that are specific to this project Electric motors of all sizes and descriptions are built for specific applications For our electric vehicle project we decided to use a squirrel cage AC induction motor To use this motor for such an application it is obvious that some tuning of the motor controller is required To tune the motor we developed a LabVIEW application that enables you to tune the PID variables Then after starting the motor you can watch the motor response in real time Motor response is critical to the overall operation of the EV system When a new motor is connected to the motor controller circuit b
29. 1 The DMX Portal is a compact lighting control unit It s designed around a WIZnet 5100 Ethernet con troller and a Microchip Technology PIC18F4620 The WIZnet development board is secured to the right side of the PIC development board The five pin XLR connector and RS 485 level converter are on the add on board behind the PIC development board 14 Issue 217 August 2008 The DMX Portal Obtain Lighting Control Via Ethernet Ready to build your own DMX lighting controller Matt s design enables him to remotely control up to 512 channels through an IP based network or directly interface them to embedded systems with a serial connection It is perfect for distributed lighting systems where low cost Ethernet wiring is a better option than RS 485 wiring that change frequently or need to be adjusted on the fly In applications such as permanent installations or automated applications the programming doesn t need to change frequently but the appli cations usually require the lighting con troller to be controlled from another sys tem instead of through physical controls For this reason the DMX Portal does not have a physical programming interface Instead it offers RS 232 and Ethernet communication interfaces and two dif ferent protocols which allow it to be used in a variety of different applications The system has an effects engine to automatically generate timed fades with simple commands It also allows user defined scenes
30. 15 Banks for context switching enables 37 5neec 6 cycles interrupt latency time High Integration 512KB On Chip Flash 32KB On Chip RAM Advanced 16 bit PAM timers to drive two motors sumultangcushy 125usec 12 ba A D conversion with 3 ample amp hold circuits Gore Gartre hanch 2007 2008 Wordeids Microcentnolier Vendor Peers 317158 Starter Kit tor SHTATIT RORTZ1 55000BE USE Emulator HMMS CUT 1H ABOVE THE GROUND PLANE by Ed Nisley IR Proximity Sensing Ed takes a look at IR proximity sensing after seeing a colleague s homebrew chord keyboard Even if you don t need a hand mounted keyboard knowing how a contactless switch works should come in handy A recent Mid Hudson Valley Linux Users Group meeting featured Greg Priest Dorman demonstrating his wearable Linux computer system He s been using the homebrew chording keyboard shown in Photo 1 for the last decade with a succession of comput ers that each ran afoul of Moore s Law The key clicking isn t objectionable and indeed seems quieter than most laptop keyboards Perhaps that s because he removed several coils from each return spring to achieve faster and less tiring typing The only disadvantage seems to be the structure holding the thumb switches I immediately thought of mounting IR proximity sensors over my fingers out to the first knuckle so that extending rather than flexing my fingers would activate the switches However
31. 2 Boot ROM Code RAM External EEPROM Data RAM Step 3 Boot ROM mE Code RAM External EEPROM Application Executing code and data Data RAM Figure 2 When the second stage boot kernel is executing it must be located in code memory in an area not required by the application code This ends up being a three stage process the Boot ROM loads and executes the INIT block which changes the reset vector the Boot ROM loads and executes the second stage boot kernel and finally the boot kernel loads and executes the application restoring the original reset vector the IDDE GUI and that the build process for field upgrades be exactly the same as for factory installed soft ware As I will show later the capabil ities of the Boot ROM and the build tools outlined previously are sufficient to achieve these requirements without resorting to custom tools in the build chain SUPPORTING NEWER EEPROM There is a second issue related to the specific SPI EEPROM device used on our IMU which is an Atmel AT45DB081D a member of their DataFlash family The Blacktfin s on chip Boot ROM supports older ver sions of the DataFlash family but does not correctly support this newer mem ber the one with the D suffix The specific issue is that the D device now implements the 0x03 legacy read command while the older devices did not This causes the Boot ROM to identify it as a generic 24 bit addressable SPI flash rat
32. 217 August 2008 77 SILICON UPDATE Icy Hot The Soft Core Concept FPGAs And You by Tom Cantrell Question Does a soft core make sense for your current application Tom covers the history of the soft core technology and introduces the ARM Cortex M1 soft core and the FPGA chips it runs on As you ll see this solution from Actel and ARM makes the soft core concept more viable than ever for new applications Question You see an engineer star ing at the screen and scratching their head How can you tell if they re designing hardware or software Answer Check if they re wearing shoes Yes using programmable logic to implement hardware that runs a pro gram seems a bit circular like being in a room full of mirrors Nevertheless I ll admit I m a softie for the soft core CPU in an FPGA concept Soft core roots go back nearly 20 years a long time in terms of silicon Back then FPGAs were like hardware Superglue sticking all the little TTL chips cluttering circuit boards togeth er in one part Naturally the FPGA design tools reflected the hardware centric stance and back in the day before HDLs and synthesis still showed vestiges of TTL era roots with schematic capture ABEL PALASM state machines and the like Sure FPGAs were cool Compared to cobbling together a sea of TTL or developing a custom chip designing with FPGAs was faster easier less risky and less expensive But FPGAs were still about doin
33. 80 ms 95 ms 108 ms 121 ms 136 ms 150 ms 162 ms 178 ms 190 ms 205 ms 220 ms Table 1 These are typical PSoC ADC sampling rates and resulting reverb delays register during runtime For this appli cation the PRS8 module is initialized to use its full 8 bit range as demon strated in the PSoC technical refer ence manual Then as samples are pushed through the FIFO buffer and need to be output they are written directly to the PRS s seed register No special timing or interrupts are needed to per form this update The seed register may be updated with a new sample at any time and the output probability will fade seamlessly to the new value With a 12 MHz clock this all happens plenty fast enough for audio ADD EFFECTS TO SAMPLES The extra RAM in the CY8C29466 is needed for the effect For most DSP effects some sort of audio buffer is required to store a window of samples for processing An echo effect can be added to a stream of audio by sam pling the audio and repeating it after a short delay The echo stream is the original stream offset by a fixed amount of time Reverberation is similar to the echo effect except that the offset audio also gets attenuated sampled and echoed along with the original stream This requires a decaying feedback loop which can be switched in or out of the circuit to enable you to select whether you want an echo or a r
34. 800 404 0204 www ironwoodelectronics com Order online at www melabs com USB Programmer for PIC MCUs RoHS Compliant Programs PIC MCUs including low voltage 3 3V devices as shown M TPT t lile hr Includes Software for Windows 98 With Accessories for 119 95 Me 2K amp XP Includes Programmer Software USB Cable and Programming Adapter for 8 to 40 pin DIP 89 95 wwWw TraceSystemsinc com 301 262 0300 Temperature Monitoring Over the Internet View temperatures using a web browser Connect up to four temperature sensors Send email alerts or alarms Two built in relays www ControlByWeb com 435 750 5999 micro CSUngineering abs Qne Development Tools for PIC Microcontrollers LAB X experimenter Boards Pre Assembled Boards a Available for 8 14 18 28 and 40 pin PIC MCUs 2 line 20 char LCD Module 9 pin Senal Port Sample Programs Full Schematic Diagram Ra from 79 95 to 349 95 NE Double Sided with Plate Thru Holes a Circuitry for Power Supply and Clock Large Prototype Area Eladionic and Electro mechanical Devices Parts and Supplies Wall Transformers Alarms Fuses Relays Opto Electronics Knobs Video Accessories Sirens Solder Accessories Motors Heat Sinks Terminal Strips L E D S Displays Fans Solar Cells Buzzers Batteries Magnets Cameras Panel Meters Switches Speakers Peltier Devices and much more www allel
35. BREAK request with a value of 0000h In NET s SerialPort class setting the BreakState property causes the host to send this request with a value of FFFFh or 0000h The SERIAL STATE notification provides a way for a device to send the states of the RS 232 status signals RI DSR and CD the break state and error states for buffer overrun parity error and framing error The notifica tion consists of an 8 byte header and two notification bytes The interrupt IN endpoint returns a notification or NAK in response to received IN token packets The notification doesn t include the state of RS 232 s CTS status signal Device firmware can still read CTS on a local asynchronous port and take action as needed For example if a vir tual COM port device has data to send to a remote device that hasn t asserted CTS the virtual COM port device can store the data in a buffer and wait to transmit If the buffer is full the virtual COM port device can NAK attempts by the USB host to send more data When the remote device asserts CTS the virtual COM port device can send the buffered data and accept new data from the host To use CTS in this way the USB host doesn t need to know the state of CTS If you want to use CTS in an unconvention al way such as having a host applica tion read a switch state on a device you re out of luck with the CDC driver unless you can define a ven dor specific command that travels on the same bulk pipes
36. DQ 1000 iLoad Mini E od E E EE 3 Em Simple to use IDE WV LELGeiu The Best Selling S compiler for AVP le High quali code generation First commercial le program compression optimizer prices E d 4 Multiple platform support Flexible licensing schemes www imagecraft com Digital USB Display Ns 0 5 4 5V DC pF feed DAQ PLC Loadstar SENSORS www loadstarsensors com cc 650 938 4282 Ln T Eel L Lap rree one time setup subject to approval Uum MF Las r Aa 6 Ld A 5 double side FCB WECKS EI wwwaanylydia eon 88 Issue 217 August 2008 Solve complex signal acquisition problems positioning amp control eye environmental Bcceleration tangents Pressure vibration sonar GPS Linux Driver 16 bit analog inputs and outputs Million sample FIFO eliminates interrupts Wide analog input and output ranges 40 C to 2 Standard Order 24 7 fast and easy N www stx104 com heip istx104 com 608 256 0767 x24 CD CIRCUIT CELLAR The number one choice in PCB Design just got better EAGLE V5 0 Highlights Displey Zoom and Grid History Lock functian for Parts unlimited nametvalue atiribules far parts mare group te alher Beet wo modilying the board reader sheets with drag amp drop or insert new sheris REPLACE function for the schemabc ed
37. EEPROM one at a time stopping only when it gets to a block that has its FINAL flag set After processing that block the Boot ROM jumps to the address con tained in the Blackfin s reset event vector which should point to the cold start entry point of the newly loaded code The Boot ROM initializes this register to a default value but it is possible to modify this register and other aspects of the state of the Black fin through the use of INIT blocks A block that has its IGNORE flag set may or may not contain data bytes it usually does but the Boot ROM skips over such blocks alto gether it simply adds the length of the block to its current SPI EEPROM address value and looks for the next block Such blocks can be used to hold information for a second stage bootloader program or for the applica tion itself Any block that does not have the IGNORE flag set is either a data block or a ZEROFILL block In the first case the data associated with the block is copied to the specified target address for the specified length In the second case there is no data associated with the block in the EEPROM but the specified target memory address is filled with bytes of zero for the speci fied length Analog Devices ADIS16350 accelerometers A data block that has its INIT flag set is called an INIT block and it must contain Blackfin code that begins execution at its load address When the Boot ROM encounters such a bl
38. Figure 5 The clock is toggled and data is read by assembly instruc tions as opposed to using a hardware peripheral that could do this in the background automatically Limited memory can be problematic for two reasons The obvious problem you have limited space in which to cram your application Writing in assembler is sometimes the only way your application can fit because a higher level language might require overhead that can put you over the space available Another problem aris es because they generally have few or no hardware peripherals This means you can chew up precious memory just supporting that function which then leaves even less for the applica tion This application requires only approximately 30 of the 1 KB pro gram space available to the PICI2F510 That includes the soft ware SPI and integer division routines The application periodically sam ples the Hall effect sensors by read ing in 4 bytes of data and stores the www circuitcellar com data to a small table see Figure 5 Two variables salt and water are used to indicate float levels They are initialized to 32 one more than the maximum level of any sensor in this case 32 sensors 0 to 31 The table is scanned LSB 0 through MSB 31 to find a low If a low is found indicating the sensor is seeing a magnetic field then the bit counter value is stored in either the salt or water variable The salt variable is tested to see
39. Rather it s The Knowledge i e FPGA design expertise you can bring to bear The difference in the quality of results i e silicon area power and speed with or without it is large sure ly pivotal for many design in decisions The catch 22 is that you need The Knowledge to make a credible deci sion whether a soft core makes sense for your application That means you ll have to acquire The Knowledge in order to determine if you need it Before I bite that bullet I think I ll check into some other ways to skin the FPGA cat When it comes to program mable logic I know there are folks who share my there s got to be a bet ter way sentiment Stay tuned al Tom Cantrell has been working on chip board and systems design and marketing for several years You may reach him by e mail at tom cantrellQ circuitcellar com REFERENCE 1 Actel Corp The Advantages of the 32 Bit Cortex M1 Processor in Actel FPGAs 2007 www actel com documents CortexM1_Advantages_ WP pdf SOURCE Igloo FPGA and M1AGL DEV KIT SCS Cortex M1 enabled Igloo starter kit Actel Corp www actel com www circuitcellar com IDEA BOX THE DIRECTORY OF PRODUCTS AND SERVICES AD FORMAT Advertisers must furnish digital submission sheet and digital files that meet the specifications on the digital submission sheet ALL TEXT AND OTHER ELEMENTS MUST FIT WITHIN A 2 x 3 FORMAT Call for current rate and deadline informati
40. Technology Devices International FT232R USB UART The chip handles all USB specific commu nications in hardware and has an asyn chronous serial port that can interface to a port on a microcontroller FTDI provides drivers for Windows and other operating systems A similar chip is FTDI s FT245R USB FIFO which has a parallel interface instead Device Configuration Interface communication Header functional Abstract control model functional Union functional Call management functional Endpoint interrupt in Interface data Endpoint bulk in Endpoint bulk out USB Standard descriptor type Class specific descriptor type Figure 2 A USB virtual COM port device can use the USB CDC class drivers provided by Windows and other operating systems A device that exchanges vendor defined data can use these descriptors www circuitcellar com CIRCUIT CELLAR TOTALPHASE High speed USB monitor with real time capture and filtering I2C SPI amp GPIO interface to USB emulates master and slave devices Non intrusive 12C SPI and MDIO bus monitor with 20 ns resolution www totalphase com 408 850 6500 sales totalphase com Issue 217 August 2008 71 of a serial port These chips are a quick way to add a USB port to a design Many exist ing devices with asynchronous serial ports can use a USB UART to con vert to USB with no firmware changes Other companies with
41. The other benefit is that LabVIEW enables you to build a functional GUI with little work The code for the utility inter faces I wrote could easily be enhanced to behave like the final user interface of a project To demonstrate how to make a final user application I wrote a virtu al lighting board application based on the same code I used for my utility interfaces see Photo 4 The virtual interface mimics the user interface provided by lighting boards by provid ing sliders that can be attached to sets of DMX channels Buttons for other common features such as tem porarily setting all lights to off also known as a blackout or disabling the DMX output to enable the lights to go into Power Down mode are also provided Earlier I mentioned that the fast bina ry protocol was based on the protocol of the USB DMX project A major reason for this decision was that there is a free lighting control program available called FreeStyler that provides excellent www circuitcellar com DPX Portal Binary Protocol Interface Serial Parti Bil ck Diae pam an M T nari E LS USB Oscilloscope for 169 50 Be ER E Queis Dh iiw Lb ic amd Spectrum Amalyzerz Generator H TE www HobbyLab us Photo 3 The code in LabVIEW is written graphically using a programming principle known as data flow Each block in the diagram represents a function that will execute once data has arrived on each of its inputs Outpu
42. Turn to page 44 for the second part of Chris Paiano s series about helpful PSoC design techniques He describes how to enhance his eight channel mixer project with DSP effects a user interface an inter com mode and more Starting on page 70 Jan Axelson describes the development of a USB virtual COM port As you know physical COM ports are becoming a thing of the past This project proves you can use an MCU with a USB controller to build and program a USB virtual COM port of your own In IR Proximity Sensing Ed Nisley describes the basics of reliable IR sensing p 40 He explains how he updated a hand mounted chord keyboard with sensors that enable him to activate switches with his thumb You can use the technique for many of your future designs Do you get your water from a well Columnist Jeff Bachiochi does In fact his neighbors use the well too Because several households pull from the same water source located on his property Jeff is the guy who handles its upkeep Being the inventive engineer that he is Jeff recently built an MCU based monitoring system for the well In Water War Prevention he explains how the design enables him to keep tabs on the system without having to periodically enter the dungeon pit p 52 At the Embedded Systems Conference in San Jose last April sev eral readers told me how much they loved Robert Lacoste s solution focused columns This month Robert delivers another handy article
43. Valerie Luster E mail val luster circuitcellar com Cover photography by Chris Rakoczy Rakoczy Photography www rakoczyphoto com PRINTED IN THE UNITED STATES CONTACTS SUBSCRIPTIONS Information www circuitcellar com subscribe E mail subscribe circuitcellar com Subscribe 800 269 6301 www circuitcellar com subscribe Circuit Cellar Subscriptions P O Box 5650 Hanover NH 03755 5650 Address Changes Problems E mail subscribe Q circuitcellar com GENERAL INFORMATION 860 875 2199 Fax 860 871 0411 E mail info circuitcellar com Editorial Office Editor Circuit Cellar 4 Park St Vernon CT 06066 E mail editor 9 circuitcellar com New Products New Products Circuit Cellar 4 Park St Vernon CT 06066 E mail newproducts circuitcellar com AUTHORIZED REPRINTS INFORMATION 860 875 2199 E mail reprints circuitcellar com AUTHORS Authors e mail addresses when available are included at the end of each article CIRCUIT CELLARG THE MAGAZINE FOR COMPUTER APPLICATIONS ISSN 1528 0608 is published monthly by Circuit Cellar Incorporated 4 Park Street Vernon CT 06066 Periodical rates paid at Vernon CT and additional offices One year 12 issues subscription rate USA and possessions 23 95 Canada Mexico 34 95 all other countries 49 95 Two year 24 issues sub scription rate USA and possessions 43 95 Canada Mexico 59 95 all other countries 85 All subscription orders payable in U S funds only via Visa MasterCard int
44. a SER RN You the Electronics ECC and Bad Block Handling PCB Design File System with Std C Lib API PCB Assembly Enthusiast FAT File Structure amp Much More Page Caching to Maximize Focusing on 8 16 bit control Performance and Minimize RAM D l 20KB Code Size modules for the following apps RAM Required lt 1 Flash Size automotive industrial www smxrtos com consumer We Need Beta Testers Now PEL 7 WWW Sign Up At icro Digital inc Tz machdesignservices RTOS innovators g www solderbynumbers com 800 366 2491 sales smxinfo com com 1 6004 Products M ww Pesifn ores com N EW HE TECH C PRO for the Microchip PIC32 MCU Family C Compiler FREEWARE New PRO compiler also operates in Lite mode with no time or size limits Compact Complete AVR Kit 16K ImageCraft CC AVR compil ler Medgal kit with LED keypad LCD and more D 10 dea software proj jects 1 E Battery INCLUDED EE Perfect for learning embedded programming and the Atmel AVR Test Equipment 5 USB PC 2 CH cip lar ter hep RT free LUN microchip htsoft com portal CC_20 www imagecratt com Inioaimagec ratt com PERCY GR TIFT ES l650 493 9326 FAX 450 493 9329 90 Issue 217 August 2008 CIRCUIT CELLAR www circuitcellar com The 69 PLC Work as Stand Alone Ladder Logic PLC Or as Smart Remote I Os of PC PLCs RS485 allows 256 units to be networked Incredibly Easy
45. ages to the gate emitter connection They also provide opti cal isolation of control signals from the high voltages that are being controlled We chose the off the shelf gate driver assembly BG2B 5015 kit from Powerex To produce the firing voltages the circuit employs an isolated DC DC converter module represented by the DC DC converter module block diagram see Figure 2 The DC DC converter enables the driver board to be run off of a single DC supply that takes 15 V and converts it to an isolated 24 VDC This voltage is then placed across a resistor and Zener diode network that provides isolated 15 8 V at V pin 3 and 8 2 V at V pin 1 with respect to the zero reference point V pin 2 The transformer in the DC DC converter also provides 2 500 VRMS protection to the gate driver assembly module The DC DC converter provides an isolated power output to pins 4 and 6 on a hybrid IC IGBT gate driver represented by the gate driver assembly module block diagram see Figure 21 5 The gate driver assembly uses the control input at pin 13 and 14 to bias the gate emitter connection in the gate driv er module appropriately to turn the IGBT on or off The 15 8 V signal at V pin 5 ensures that the IGBT will be saturated in the on state The 8 2 V signal ensures that the IGBT will not be switched on by noise or Miller capaci tance between the collector and the gate The output stage of this assembly provides high current to the gate so proper
46. an output voltage has a gain with units of V A an impedance and is known as a transimpedance ampli fier That sounds complicated but an ordinary resistor has a transimpedance gain equal to its resistance Indeed the resistor shown in many sensor datasheets may suffice but the photodiode s reverse bias will vary with its photocurrent Worse the resistor forms an RC low pass filter with the photodiode s junction capaci tance which can dramatically slow the voltage s rise and fall times For example the BPV23NF s junc tion capacitance is about 20 pF with 2 V reverse bias The 100 kQ resistor required to get 1 V from a 10 nA pho tocurrent forms a low pass filter with E ke T h T T b ee tt Frag 13 5 Ea NIS Duty cyt 113 65 Photo 4 Simple DC threshold detection fails when confronted with ambi ent light The two lower traces show the SMD sensor s response with and without an incandescent flashlight shining on the target The baseline offset is larger than the signal The upper trace shows the low active IR LED drive CIRCUIT CELLAR Photo 3 This ugly breadboard implements the transim pedance amplifier and filters shown in Figure 1 A signal generator pulses the IR LED inside the brass tube through a one transistor buffer The fourth op amp on the far right provides voltage gain The green and yellow clips lead to a pair of 9 V batteries that supply quiet DC power a 2 us time cons
47. both worlds for designers choosing between a 16 and 32 bit solution A broad range of embedded software solutions are avail able including RTOS design tools 10 100 Ethernet soft ware USB stacks and file systems Known for its efficien cy high performance and small footprint the RTXC fami ly of solutions provides an easy to use flexible solution for developers who decide to use the STM32 platform When using the STM32 family you can select the embedded development tool that best fits your needs RTXC products are available with support for the IAR Embedded Workbench for ARM EWARM and the RealView microcontroller development kit MDK ARM from Keil The RTXC family comprises four kernel architectures offering distinct performance advantages for each of the major processing models The RTXC ss single stack uti lizes a lightweight specialized executive to support high data rate and signal processing applications The RTXC ms multistack is optimized for control processing using an event driven prioritized preemptive scheduler The RTXC dm dual mode marries RTXC ms and RTXC ss It is ideal for convergent processing applica tions which combine DSP dataflow and RISC control pro cessing in a single core processor Both RTXC ms and RTXC dm are brought together under RTXC mp multi processing in various combinations to support multicore and multiprocessor implementations Contact Quadros Systems for pricing Qua
48. bytes to determine the base address of the active loader file in the EEP ROM It will then skip the first two DXE images in this file the INIT block and the boot kernel itself and load the third DXE image which is the application firmware However there is one additional twist When the boot kernel is execut ing it will be loading the application code so the boot kernel itself must be CIRCUIT CELLAR located in code memory not needed by the application There are two ways to achieve this the boot ROM could load the boot kernel at the default address and then the boot kernel could relocate itself to a different address higher up in memory before continuing But in many ways it s simpler to just have the boot kernel load and run at the higher memory address to begin with This adds the requirement that our INIT block must set the reset vector to that other address so that the Boot ROM will jump to that address when it fin ishes loading the boot kernel and that the boot kernel itself must restore the default reset vector value before it loads the application code This still leaves open the possibility that the application can have its own INIT block that sets a non default reset vector value But constructing a loader file with two or more INIT blocks while possible would require a non standard development tool chain As a result of all of this we re going to build each application image LDR file
49. changes Like a programmable logic controller the FM6124 features simple device settings and data retrieval for easy system integration and a shorter design in cycle The FM6124 is designed for broad industry use in the industrial control med ical and metering markets The EDR can perform in a host of application e g activity equipment environmental monitoring maintenance scheduling power system management automotive industrial automation event recording vehi cle pedestrian traffic counting and surveillance systems The FM6124 features 32 KB of FRAM memory that can be used to store event records Up to 24 KB of F RAM can be configured to store event user data The on chip RTC with a calendar enables event time stamping and can function as a system clock and calendar The EDR includes 12 digital inputs that can be individually configured to trigger event recording on either a rising or falling edge The FM6124 s F RAM memory can store up to 4 000 event records The device features an PC inter face that sustains communication speeds up to 100 kbps The PC interface allows for the flexible placement of the FM6124 chip away from the host system and closer to the equipment and sensors it is monitoring Up to four FM6124 devices can share the same PC bus The FM6124 starts at 7 50 for quantities of 1 000 Ramtron International Corp www ramtron com CIRCUIT CELLAR www circuitcellar com kiPololu Re L OXON OS a
50. chose a PWM technique known as space vector modulation SVM To help illustrate the advantages of SVM a quick review of some of the other techniques for motor control is in order The simplest method of motor control is the square wave or six step inverter The method is not processor intensive It uses simple circuitry but does not simulate a sine wave effectively This waveform generates significant total harmonic distortion THD that makes the system power inefficient Energy is lost as heat vibration and noise A multistep inverter can be created that can generate 26 Issue 217 August 2008 more than six voltage steps in the waveform This method simulates a sine wave more closely but requires much more complicated circuitry additional switches and trans formers The resulting control is better than the six step inverter but still generates an enough harmonic distortion to make it inefficient Next there are PWM techniques These techniques improve the simulation of sine waves and therefore reduce the THD There are many PWM clas sifications The two discussed here will be sinusoidal PWM specifically the volts hertz V Hz method and space vector modulation SVM ACIM speed level and torque level can be controlled by varying the voltage and frequency supplied to the motor The V Hz method uses a constant K to relate the desired drive voltage to the choice of input frequency with the calculation koX Hz Because
51. fin DSP chip receives a hardware reset it begins executing code at address OxEF000000 which is the beginning of its on chip Boot ROM The Boot ROM examines the external Boot Mode pins which indicate the source of the application code which can be an external 8 bit parallel PROM an external SPI PROM Black fin is a SPI master or another processor connected to the SPI Blackfin is a SPI slave In our application the mode pins indicate that the boot device is an external SPI flash memory EEPROM so the Boot ROM begins loading and processing blocks from that device Figure 1 shows the key features of the Blackfin that come into play CIRCUIT CELLAR DRES ADIS 16350AML 7 ox AML ADEVI21406 3 URA 3431 dst Photo 1 The Analog Devices ADIS16350 sensor is married to a small board carrying a Blackfin DSP to do post processing on the data The CPU is the large chip in the center of the PCB and the SPI flash PROM used for booting is the eight pin device to its right The structure of a loader file con sists of a series of blocks of various types Each block contains a header and the header contains a target address a length and several flags The flags include IGNORE FINAL ZEROFILL and INIT The block will also contain data bytes following the header as long as the length is nonze ro and the ZEROFILL flag is not set www circuitcellar com The Boot ROM firmware processes blocks from the external SPI
52. for breakfast and lunch You may want to design a system that uses DMX controlled dimmers for each room and automatically dims the lights in each room at the start of dinner You may also want the ability to adjust the lighting in each room separately to com pensate for the amount of light from windows or for special events In this situation scenes are a poor program ming method because the exact level needed for each dimmer channel is not always the same A standard lighting board would require you to have a scene defined for each possible combination of brightness in each room Even if you allow only five discrete brightness levels per room and had four rooms this would result in 625 scenes to cover every possi ble combination Because the DMX por tal gives you a way to programatically PIC Ethernet development board se WIZ810MJ Evaluation board Figure 2 The DMX portal includes three boards The PIC18F4620 microcontroller has more than enough power to handle the functionality of the DMX features command processing and the RS 232 interface The WIZnet evalu ation board offloads all of the processing requirements for an Ethernet interface and connects to the PIC18F4620 via the SPI port CIRCUIT CELLAR Issue 217 August2008 15 control the level of each channel and recall saved scenes the task would be much simpler A scene could be defined for the default levels of every room at the start of each meal
53. generator Agilent Technologies Inc www agilent com AD9833 Waveform generator AD9910 direct digital synthesizer and AD9912 direct digital synthesizer Analog Devices Inc www analog com PICC Lite Compiler Hi Tech Software www htsoft com Proteus VSM Mixed signal simulator Labcenter Electronics www labcenter electronics com MCP6002 op amp and PIC16F629A microcontroller Microchip Technology Inc www microchip com Scilab Simulator Scilab www scilab org Issue 217 August 2008 69 FEATURE ARTICLE Create A USB Virtual COM Port Physical COM ports are disappearing from PCs but the right firmware can make a USB device appear as a virtual COM port As Jan explains you can use almost any microcontroller with an embedded or external full or high speed USB controller to design and program your own USB virtual COM port device by Jan Axelson access to it A USB virtual COM port is a soft ware interface that allows applications to access a USB device as if it were a ou ports have long provided a convenient way for PCs and embedded systems to exchange information The traditional COM port on a PC is an method The application reads and writes to the port as needed When finished communicating it closes the port to allow other applications RS 232 serial port on a motherboard or expansion card Recent PCs often skip RS 232 in favor of USB But with the right firmware a USB device can appear as a vi
54. gt ReadingSetsBetweenSerialBursts if SendSerialNextChance TransmitSerial SendSerialNextChance 0 SerialOutputCounter 0 every cycle its time to write if CheckModeButt Now here tons pressed check for the other button If both but StoreSettings SetIndex while CheckModeButt else tap 1forrSetlndexe 4 Set lIndex 1 LoadSet SetIndex CIRCUIT CELLAR www circuitcellar com nobody wants to move the chip to test new firmware every reburn Because this project utilized all I O two of the programming pins are used in the cir cuit P1 0 and P1 1 They are typical ly the last two pins you will use in a design but because they are needed they require two jumpers The jumpers must be removed to burn the PSoC and installed to operate They connect two of the potentiometer input lines Jockeying two jumpers is still in my opinion preferable to jockeying a chip from socket to socket The five pin connector is designed for the Cypress Mini Programmer CY3210 MiniProg1 which is an economical development PSoC burning tool EXAMPLE PROJECT NOTES When the mixer first starts it always loads Set 1 from memory and enters Reverb mode Thus it speaks 1 Reverb When the Mode button is pressed it cycles through the three available modes Intercom it says Com Pitch Shifting it says Pitch and back to Reverb it says Re
55. in darkness Turning the LED on and off at a known frequency produces an AC photocurrent that can be extracted from the ambient illumination amplified as needed then demodulated to produce distance information The signal amplitude depends on the object s reflectivity and distance just as before but now the signal can be separated from the background illumination I chose an 8 kHz modulation fre quency based on the relatively slow rise and fall time of the SMD sensor I didn t need a high speed transim pedance amplifier to achieve that Figure 3 Plotting voltage versus range on log log scales shows nice 1 rx responses at least beyond a few millimeters The voltage is the RMS output of the 8 kHz four pole band pass filter boosted by an additional op amp stage bandwidth but I left U1 in the cir cuit to simplify the discussion U2 and U3 along the bottom of stuck active even with the LED off If you measure the background level perhaps with a microcontroller s CIRCUIT CELLAR 42 Issue 217 August 2008 www circuitcellar com Figure 1 each implement a two pole band pass filter centered at 8 kHz with Q 10 for a bandwidth of about 800 Hz The filter shape isn t critical I used the Analog Devices Filter Designer web site to create 1 dB Chebyshev filters with a multiple feedback topology to reduce the parts count The pair forms a four pole filter with a net 500 Hz bandwidth Current source I2 in Figure 1 is an
56. it truly does no harm m3 ues F P adi PA d A 5 steve ciarcia circuitcellar com IEK 96 Issue217 August 2008 CIRCUIT CELLAR www circuitcellar com LR P red T m 2 ami meme rr m lut i TU mlt T e 3 ST L CEMEGER AERE ES ERE 1 9 in ena ss all BE HO HOECUHICR ee ma wm rx x RG RS mda 15 db XB ab Ma 1 lt anim m am ran m vir n TT aa B Professional H ERT Em Keres hae S ud CEE Hardware Capture Mb z keee a Software Analysis js Cee do 35 Automatic Real time Hardware Compression eliminates the neec to reduce resolution Our newest versior makes dead time insignificant Edge and Pattern Triggers on all models cuales ad lode also includes Range gt lt le gt lt and Stable Matches with Beata onda flexible cascadable Seque DC rs with pe 485 counters Pattern S searches with Match amp Duration Specia lied Sequential Searches EE Serial and State Mode Signals Display FC Synchronous SPI Asynchronous RS 232 State Boolean Bus and Analog Data Single or Dual Waveform Views Resolution Zoom in Wave Views Time based Link Groups for all views Specialized Exports from Dati Tables and List Views f que nal Data Tables Drag amp Snap Markers Click to Center function Snap Previous Next function Print or Save Images with comments USB 2 0 480 Mbps USB 1 1 compatible 12 Mbps
57. making an optical sensor work under real world conditions requires somewhat more circuitry than the datasheet might lead you to believe In this column I ll take a look at IR proximity sensing which will be useful even if you re not inter ested in weird keyboards REFLECTIONS ON LIGHT Optical distance measurement requires different techniques for differ ent tasks Applying the wrong method can cause serious headaches so sort ing through the options is a good first step for any design Triangulation makes use of the geom etry between the emitter receiver and a remote object Given a known distance between the emitter and receiver and 40 Issue 217 August 2008 the measured angles between the ends of that baseline and the object you can solve the triangle and determine the object s distance This works well for surveyors even before GPS simpli fied the baseline measurements and scales down to centimeter distances Time of flight measurements take advantage of light s 1 ns ft speed A laser beam modulated with a pseudo random bit sequence bounces from the object to a photodiode and is then demodulated back to bits A high speed autocorrela tor matches the incoming and outgoing bitstreams to find their time difference which is directly proportional to distance This also works for land surveyor dis tances and scales well to a few meters Interferometry measurements split a single laser beam into two paths boun
58. may think of it as a miniature passband too in the look up table is not infinite unwanted DDS generator working on DDS also has another issue that s This will give another error on the the unused bits and unfortunately often more crucial than quantization output Contrary to DAC quantiza added to the output Once again the errors phase accumulator truncation tion this error will not generate theory helps It says that the relative Extremely easy to install and use Distances up to 100 meters 323 feet 500 meters with extended antenna 1649 feet Bluetooth Serial Profile One to One virtual cable or selectively connect one to many E Cotimunicame with Bluetooth enabled PDAs Laptops Smartphones amp Computer No special software required Other Products Professional serial communication libraries amp development tools PCI PCMCIA Universal PCI amp ISA multiport R5232 Rs422 A Hs485 cards Bluetooth USB Dongles USB Serial Adapters JK microsystems 64 Issue 217 August 2008 CIRCUIT CELLAR www circuitcellar com Spectrum log scale N 16 P 16 B 10 W 5 169 30 000 40 000 50 000 Figure 7 This simulation still done with Scilab shows DAC quantization effect These are simulated output spec tra of a 1 GHz 16 bit DDS tuned to provide a 78 MHz output The top curve is with a 10 bit DAC The bottom curve is with an 8 bit DAC The vertical scale is logarithmic BE ans igurir m
59. modules i Optically solated Inputs Reed tac Helay Outputs Form C Relay are the fastest most Outputs Digital AnalogCombo 7 rellable way to connect Status Indicator LEDs for 0 Communicatian Fault amp Status I O to any computer Field Removable Terminal Block Connectors High Retention USB Type B I Connector Rugged Plastic Tabletop Enclosure Extended Temperature Option Available FOCUS On Success r epos sales sealevel com gt 864 8 43 8 48 Issue 217 August 2008 CIRCUIT CELLAR from my favorite TV shows into this project Instead I used my sound card to make my own recordings I started with the three modes the mixer would have available to it I recorded the words Reverb Pitch Shift and Intercom Next I time compressed them to play back faster without changing pitch a func tion of Sony s Sound Forge 8 0 which I used for the recording and manipulation to save some space and make sure they still sounded like words I then converted them down to 8 bits and resampled digital ly to 7 8 kHz to match the rate pres ent inside the PSoC Using this sam pling rate enables the implementation of the WAV player without the need for a separate counter or timer module to generate the sample output inter rupts Again this is not high fidelity by any means but it is reasonably intelligible as well as not being too tough on the ROM Using my Wav
60. off with cellar10 coupon code Temperature Humidity Illumination www circuitcellar com CIRCUIT CELLAR Issue 217 August 2008 19 All you need to do is put the DMX Portal into Binary Protocol mode and then point FreeStyler to the correct COM port FUTURE DEVELOPMENTS Like any project there is always room for improvement I would like to improve the DMX Portal s RS 232 hardware buffer The PIC18F4620 pro vides a 2 byte hardware buffer to help give the processor time to process incoming data if it can t get to it immediately As I discussed in the Firmware section I chose to make some processes block the execution of other interrupt driven processes to deal with time sensitive requirements or race conditions involving modify ing memory in the middle of these tasks There is a downside to this approach When the DMX output is enabled the processor is fully occu pied for 22 668 ms while a frame is sent Because the DMX output refresh Ew I E Rw b T Aiur te R DESIGN your two or aue ner PC board SEND us your design with just a click RECEIVE top quality boards in just days exbresspcb com 20 Issue 217 August 2008 CIRCUIT CELLAR consists mostly of wait commands to generate the proper data rate timing speeding up the processor would not reduce the amount of dead time where the processor could not handle incoming data Even at the slow data rate of 9 600 bps a single byte takes only abo
61. period If levels other than the defaults are required the commands in the DMX Portal control protocols make it easy to modify the levels of individual channels on the fly With this level of control you can easily implement a system that provides many more manual brightness levels for each room without programming a ridiculous number of fixed scenes HARDWARE As you can see in Photo 1 the DMX Portal prototype consists of three boards Figure 2 shows how the boards are con nected The main board is a simple PIC development board which contains power supplies an RS 232 interface IC and a 256 KB serial EEPROM The board also has a few LEDs and headers for the PIC s debug lines and the remaining I O pins see Figure 3 A PIC18F4620 microcontroller is the core of the system It is responsible for maintaining the current state of all DMX channels generating the DMX output stream processing incoming commands and generating effects like fades This project uses many of the PIC18F4620 s peripheral hardware features The inter nal EEPROM is used to store user defined settings that are applied when the system is turned on such as whether to enable DMX output a value to initial ize all channels to and IP settings for the Ethernet interface The PIC18F4620 s serial communication hardware is used to implement the RS 232 asynchronous interface and SPI communication to the external EEPROM and the W5100 Eth ernet controller
62. route and speed Shows data on Google maps 175 Super TrackStick II 239 Temp RH Sensors UPSICAP novel ambient sensors and modules accurately measure temp RH Amazing range response 0 to 100 RH 90 to 85degC 0 25s Interchangeable without recalibration from 3 40 FREE COFFEE Call 1 888 7SAELIG Mention Offer SBW to get a free Starbucks Card with your 50 order or more While supplies last not available with any other offers Saelig Alan Lowne says started Saelig as an engineer for engineers Saelig an Olde English word meaning happy is what want for my customers my staff and myself See my blog for behind the scenes company details business hints kudos etc PRIORITY INTERRUPT by Steve Ciarcia Founder and Editorial Director A Reactive Necessity don t know how we got started on this conversation at the party last night but we were all sitting around the fire pit and the subject of sports obsessions came up Almost all of the wives started describing the various lifestyle accommodations they had to deal with during the baseball basketball and football seasons Sympathy was offered to those dealing with multiple sports or seasons that never seemed to end There was an almost unanimous opinion among the wives that their husbands were absent a good deal of the time fulfilling various obsessions While do watch an occasional event felt confident that was goin
63. software defines how to use the data Bulk transfers have the highest through put on an otherwise idle bus but have no guaranteed timing Printers and USB virtual COM port data use bulk transfers Interrupt transfers have guaranteed maximum latency or time between transaction attempts Mice keyboards and virtual COM port status notifications use interrupt transfers Isochronous transfers have guaranteed timing but no error correcting Streaming audio and video use isochronous transfers CIRCUIT CELLAR www circuitcellar com Tx a OUT THI RX RS 232 Data RS 232 r RTS lt Flow control optional CTS RS 232 Interface chip Figure 1 A microcontroller with a UART and an embedded USB device controller can function as a USB RS 232 Device controller Generic I O Output bit Input bit Microcontroller bridge The RS 232 port in this example includes two data lines and two lines for flow control built in serial port Many USB virtual COM port devices function as bridges that convert between USB and RS 232 or other asynchronous serial inter faces But a virtual COM port doesn t have to have a serial interface at all Some virtual COM port devices con vert between USB and a parallel inter face Or a device might just read and store sensor data from an on chip ana log port and send the data to a PC via USB One way to create a virtual COM port device is to use a dedicated chip such as a Future
64. stable frequen cies Are You Locked A PLL Primer Circuit Cellar 209 I also briefly introduced another interesting concept the direct digital synthesizer or DDS for short At the time I prom ised to dig into DDS techniques in a future column This month I ll make good on my promise You may also remember that I already presented a DDS project back in 2001 but this time I will go further than just describing a project DDS GEN Circuit Cellar 129 and 130 My aim is to help you understand how DDS techniques can help you in future projects To do so I will describe the pros and cons of using them So come with me on a journey to DDS world DDS BASICS The simplest form of a digital wave form synthesizer is a table look up generator see Figure 1 Just program a period of the desired waveform in a digital memory Why not an EPROM for old timers connect a binary counter to the address lines of the memory connect a DAC to the mem ory data lines keep the memory in Read mode clock the counter with a fixed frequency oscillator F and voila you ve got a waveform on the 60 Issue 217 August 2008 DAC output Don t forget to add a low pass filter to clean the output sig nal with as you know a cut off fre quency a little less than F 2 to please Mr Nyquist This design works but it is not too flexible If you want to change the output frequency you need to change the clock frequen cy
65. take yau from mystery to mastery with CPLDs and programmable logic Learn to turn software into gm hardware f www XGAMESTATION COM Issue 217 August 2008 37 block loading functions as the Boot ROM itself THE FIRMWARE UPDATE PROCESS So far we have not addressed the question of how firmware updates actually get programmed into the EEPROM in the field This could be implemented as a function within the boot kernel itself but this would make the boot kernel significantly larger and would lock in the implementation to loading methods that are known at the time the IMU is manufactured Remember although every copy of the applica tion code contains a boot kernel only the one loaded at the factory ever gets executed Therefore we chose to place the firmware that implements the field update function into the application code itself The application uses a message based interface via the Blackfin s UART port and messages specific to the firmware update func tion have been added to that inter face While this gives us tremendous flexibility to add new functionality to the update function at any time it also creates the onus that the update function be bug free if we ever break the field update function by introducing a bug then the unit must be disassembled so that the CPU s JTAG interface can be accessed to reprogram the EEPROM from scratch Any number of separate loader file images can be store
66. thanks to Moore s Law and I especially like what Actel is doing with flash memory FPGAs New and improved chips with a popular and practical soft core what more could a designer ask for How about some good tools Given the historic ASIC replace ment strategy it s no surprise that FPGA design tools are pretty compli cated Actel s Libero design suite is no exception with its rather daunting mix of third party e g Synplicity syn thesis Mentor Graphics simulation and in house e g floor planning power estimation place and route tools No getting around the fact you really have to become something of a chip design expert to get the most out of Libero see Photo 2 But FPGA suppliers are trying to make life a little easier In Actel s case they front the process of building an SoC with a tool called CoreConsole see Photo 3 It s kind of a hardware pre processor that allows you to cut and paste at a block diagram level choosing from a decent library of pre fabbed pro cessing and I O functions Once you ve l Eu l Eis L IIF j IE Tum j kS le Photo 4 Actel offers M1 evaluation kits based on ProASIC Fusion and Igloo shown here Notice the stereo i e two port USB lash up One port is used for debugging while the other implements a virtual serial port CIRCUIT CELLAR Issue 217 August 2008 85 Rog he a Bk l a qam am Photo 5 Success The simple traffic light demo
67. that you re paying for the then some even if you don t need it Ee Ie Ear rrr oW 7 Which brings me back to the M1 Photo 2 Libero enables you to get deeply under the hood Like a shade tree mechanic trying to rebuild an debug logic Once your application is engine if you don t know what you re doing it s all too easy to fix it until it s broke 84 Issue 217 August 2008 CIRCUIT CELLAR www circuitcellar com 2E 8 0 eerie ND TE H We Lestra ARMES Cartes famiy ai procepears asd bae bse micteprecenesr vtech Pers heya garicrreancs ang wrzad gge Lmipa K mra the Auf irrireriion s o ls ol Bima Jeden md 2 pog la Lee get dla aibi g AL mese Re E Lans L it 4 B cH a L T atu Ts N E nup rmn Lisica U LAL dA Photo 3 CoreConsole makes it easy to get a design started by cutting and pasting predefined components Although they weren t yet implemented at the time of my evaluation notice the planned Cortex M1 configuration options in the dialog box need under the hood factory or field access Refer to the n C Probe A Prettier PRINTF sidebar Big deal you say You bet it is because the debug engine is practically as big as the MI core itself For exam ple on a mid size FPGA stripping out the debug cuts the amount of silicon occupied by the core from one half of the chip to just one third Needless to say the soft core option looks better and
68. the exchange ceases Unlike other fil ters the system has the distinct R1 47k Q8 VDD OUT GND A3213LH advantage of being able to clean or regenerate itself via a periodic regener ation cycle The tank s controller measures the amount of water used to determine when a cleaning cycle is necessary When necessary the con troller initiates a cleaning cycle During a cleaning cycle well water temporarily bypasses the filter while a brine solution sodium chloride NaCl or potassium chloride KCl and water flushes the mineral ions from the host resin Thus the resin is regenerated by the exchange of brine ions for mineral ions The host resin itself does not need replacing Howev er because the brine is removed and replaced with water each cleaning cycle the NaCl or KCI in the brine tank needs replenishment The brine tank can hold a few hundred pounds of NaCl or KCI pellets When the brine is replaced with water the pel lets will be dissolved by the water until saturated at which point the Figure 2 This is a modular shift register circuit that can be daisy chained to enable you to measure multiples of 8 Eight Hall effect sensors are equally spaced at 1 intervals The eight sensor outputs are latched and serially shifted via the sensor bus www circuitcellar com CIRCUIT CELLAR Issue 217 August2008 53 Figure 3 The Hall effect is a displacement of electron flow 1 and 5 within a conduc
69. to Program Our software is used by many v W colleges for teaching PLCs g N Get Free Ladder Logic Simulator Triangle www tri plc com cci htm R Tel 1 877 874 7527 PLC specialist since 1993 Weather Instruments for PCs B Ss electr nica www aagelectronica com Tiny Linux controller 16MB fast SDRAM 10 100 Ethemet 84MHz Coldfire MCU 3 serial ports R5232 4 5 MB flash memory 1 CAN port SD card socket to 2GB LCD KPD port Eclipse CDT dev env Free serial debugger 55 I O pins amp inus to burn www circuitcellar com Freescale 9S12C microcontroller DIP modules Technological M68MOD912C32 7 freescale Alliance Warmia www nanocore12 com Toll free 1 877 963 8996 T Baze T Ethernet i s 186 Processor d 40 MHz a DOS wi Flash File System a 16 Digital WO 8v DC Console Debug Port s 121 Serial Ports Hardware ChockiCabendar a 121 16 bit Timers Socket for DiskOnChip s Watchdog Timer 512K DRAM amp 512K Flash 3 75 x 2 507 s picoFlash Controller Borland CiCe 4 52 s TCPIIP PPP amp Web Server Serial Driver Library s AC Adapter and Cables Call 530 297 6073 Email sales jkmicro com On the web at www jkmicro com USB Data Acquisition ADU208 USB Relay I O Interface Complete SDK Online at www ontrak net ne USO Relay VO interface x were R vR YR YR Y RY RY R YR RR RR SCL LEE FEATURES 8 5 AMP relay ou
70. to be saved and recalled when a command or digital trigger is received These features enable the DMX Portal to fit into a variety of applications ranging from a simple virtual lighting board emulated on a PC to a self contained lighting control unit in an embedded system To keep project costs down I built the DMX Portal around a Microchip Tech nology PIC18F4620 microcontroller and a WIZnet W5100 Ethernet interface The complete system costs less than 50 making it extremely cost effective in comparison to other DMX controllers DMX PROTOCOL To understand the DMX Portal it is useful to first understand how DMX CIRCUIT CELLAR works At the highest level DMX is nothing more than a serial transmis sion of 8 bit values Data is transmit ted at 250 kbps in frames that consist of the following sections BREAK MARK AFTER BREAK MAB START CODE data slot and up to 512 chan nel data slots see Figure 1 The term BREAK means a low state where the voltage on the DMX data line is lower than the voltage on the DMX data line The term MARK means a high state where the line has a higher voltage than the line The START CODE and channel data slots each contain 11 bits which are 4 us in length The first bit is the start bit and is always low The next 8 bits are the data portion of the slot with the least significant bit first The final 2 bits are stop bits and are always high The START CODE can have differe
71. use a DDS to generate a frequency higher than the Nyquist limit far in the UHF area The ampli tude will be lower but it will work as long as your filter is well designed ANY OTHER PROBLEM Once you have managed to filter out any image frequencies will you get a perfectly clean sine signal You will but only if you have a perfect DDS with an infinite number of bits and infinite precision everywhere Unfor tunately you are not that rich One of your enemies will be DAC resolution Because the resolution B of the DAC is not so high there will be a quanti zation error which will translate into quantization noise in the output spec trum Once again I have a small SciLab simulation with two different DAC resolutions see Figure 7 The Save time amp money on your next embedded design Design your schematic Simulate your design Debug in 1 3 the time Make your PCB FREE downloadable demo Lam very pleased with the simulator got my project designed and working in no time without having to develop a breadboard Well worth every penny we paid for it Boeing Satellite Development Center El Segundo CA R4 systems INC Toll Free 865 498 8184 infof r4systems com Proteus Starter Kit 5299 Complete Systems trom 58 Works with popular compilers and assemblers AVR AGT Available for PIC 8051 Other Products PIC amp AVR Compilers PIC amp AVR Programmers Discovering PIC
72. vendor ID and product ID values identify the specific device Every device with the same vendor ID product ID pair should use the same driver on the host The serial number string index identifies a descriptor that contains a serial number A serial number pre vents unwanted COM port prolifera tion A device with a serial number retains its COM port number if it is moved to a different USB port on a Windows PC A device that doesn t contain a serial number gets a new port number on each attachment to a different port on a PC Besides a device descriptor a typical CDC virtual COM port device has one configuration descriptor and two interface descriptors Each interface descriptor has subordinate descriptors The configuration descriptor specifies power requirements and the number of interfaces in the configuration The CIRCUIT CELLAR interface descriptors tell the host how the device implements its communi cation functions The communication interface descriptor names a CDC subclass and protocol see Listing 2 Generic COM port devices and some modems belong to the abstract control model subclass The protocol is V 25ter which documents common AT com mands For compatibility with stan dard host drivers a generic virtual COM port device should specify the V 25ter protocol even if the device doesn t use AT commands The communication interface has four class specific descriptors and an endpoint descriptor
73. well designed DDS can have signal to noise ratios well above 70 dBc large enough for the vast majority of applications By the way you will find two different fig ures in the specifications the signal to noise ratio and the spurious free dynamic range They are correlated but not equivalent The former is the ratio of signal power to the sum of all noises The latter is the ratio of sig nal power to the strongest spurious frequency SOFTWARE IMPLEMENTATION Enough theory It s time to demon strate how to build an actual DDS generator There are some impressive dedicated integrated circuits around I e200 8 8080 GV VERE lt 3 E ERusiB EA L ni i ij Pare Fir Em ee imp p eee ey ibep eee ee Fein Jae Am ee uw aos h HL ERS ABE 5 Photo 1 This is the Proteus VSM in action The schematic shows you that have used a PIC microcontroller a small will examine them later For now let s R 2R 4 bit DAC and an active filter Just virtually load the associated firmware in the microcontroller connect a virtual start with a firmware based imple mentation because this month s theme is Embedded Development Programming a DDS in a general Easy Embedded Linux 169 Qty 1 E 200Mhz Arm9 CPU 16 Digital I O Watchdog 10 100 Ethernet 2 USB Battery backed Clock Calendar 2 Serial Ports We brought you the world s easiest to use DOS controllers and now we ve done it again with Linux
74. with a PSoC Cypress Semiconductor Corp 2007 RESOURCE Cypress Semiconductor Corp PSoC Mixed Signal Array Technical Refer ence Manual 001 14463 2007 SOURCES CY3210 MiniProg1 Evaluation kit and CY8C29466 PSoC mixed signal array Cypress Semiconductor Corp WWNW Cypress com Sound Forge 8 0 Sony Creative Software Inc WWW SONY creativesoftware com Issue 217 August 2008 51 FROM THE BENCH by Jett Bachiochi Water War Prevention An MCU Based Monitor For A Communal Well Jeff s Microchip Technology PIC12F510 based system monitors the water filtration system in an underground well The design indicates when the communal filtration system s brine tank is out of salt e are beginning to see some signs of public panic due to water my engineering skills to tackle a local water issue In this article I ll describe issues I have read about towns whose how I built an MCU based monitoring water sources e g wells are being system for a water filtration tank threatened by pollution both natural and man made I have also read about WATER SUPPLY cases where upstream users are divert Urban dwellers depend on munici ing increasingly large amounts of flow nal water works to provide an unend for their own gluttonous needs Per ing supply of fresh albeit treated haps Mother Nature will choose to frustrate humanity by redistributing her life giving precipitation While solutions
75. 1 with a 1 MHz GBW and an input capacitance of a few picofarads The BPV23NF capacitance is about 10 pF at 9 V reverse bias so C1 should be 15 pF obviously your results will vary Photo 3 shows a breadboard version of the circuit in Figure 1 with the IR LED hidden inside the brass tube and lump of modeling clay near the left edge The photodiode stands beside the brass tube facing a blue capacitor serving as a target A discrete LED and photodiode would be too large for hand mounted sensors so I also tried the surface mount proximity sensor shown on the left of Photo 2 It s an anonymous sur plus part similar but unrelated to an Avago Technologies HSDL 9100 I sol dered wires to the SMD pads and glued the whole affair to a connector shell for use on the solderless breadboard Photo 4 shows the SMD sensor s response to a block of wood positioned 8 mm away with ordinary fluorescent lamps overhead The upper trace is the low active LED drive The bottom trace is Ul s output voltage 500 mV corre sponds to 50 pA of photocurrent with essentially no ambient light interference The SMD sensor is probably a phototran sistor as the rise and fall times are much slower than a photodiode You could feed this signal into a com parator set to 250 mV and get a decent logic signal which is what many datasheets and app notes indicate Looks pretty good doesn t it The middle trace in Photo 4 hints at why this simple schem
76. 12 It is a 1 Gsps chip and has less modulation options but it provides a 48 bit phase register and a 4 uHz resolution up to 400 MHZ I m not sure if such a resolu tion is useful You should double check the stability of your reference oscillator too Note that the AD9912 has an interesting new feature SpurKiller channels Theoretically this feature will enable you to cancel any given pair of spurious signals It is based on nothing less than two inde pendent mini DDS generators that can be tuned to generate a signal at the same frequency as the spurious one you want to kill but in opposition of phase The circuit then adds these sig nals on the output all entirely in the digital domain prior to the DAC This feature seems to require delicate tun ing But a typical spurious reduction of around 6 to 8 dB is announced with specific configurations providing up to 30 dB attenuation Something to be bench tested someday for sure WRAPPING UP Here you are You should now have a better idea about the pros and cons of direct digital synthesis But let me summarize for good measure A direct digital synthesizer DDS will provide you with a marvelous sub hertz frequency resolution imme diate frequency hopping and efficient full digital modulation features How ever its frequency range will be limit ed to around 40 of the clock source except if you try to use image frequen cies and you may suffer from some nasty spuri
77. 293 3 ch logger for 16 bit current voltage temperature measurement KLARI MOD MC m 1900 For testing dc power battery sources Const current resistance conductance voltage and power modes 0 to 80 V and 0 to 80A 300W Transient generator Variable drop out LD300 1532 Instant Ethernet 10 100 Ethernet controller on a chip Fully hardwired TCP IP core No OS required TCP offload improves system performance PCB too W5100 integrated PHY 5 88 WIZ110SR 35 Engineering Software AudioWave LF signal generator 60 LochMaster strip board design 80 RealView realtime curveplotter 80 Profilab control log DMM or I O bd 80 I2C for PCs PCI93LV industry standard I2C card for PCs WINI2C PCI software gives windows interface to develop and debug I2C bus systems UCA93LV is USB version Transparently monitor at 400kHz 499 uniqug electronics B nf 100MHz 2 ch 16 logic scope and logic analyzer 2000 wfm s refresh rate See waveforms and logic data simultaneously Trigger on data or Bee eee 1499 DS1102CD 50MHz USB Scope PS3206 Is an impressive 2 ch 200MS s 8 bit PC scope adapter 10GS s for repetitive signals No power supply needed simple USB 2 0 connection PS3206 Bundle 1574 PROD 15 20MHz USB 14 bit Function Arbitrary wim Generators 10 built in wfms FM AM PM FSK SWEEP and BURST 6 digit 200MHz frequency counter DG1011 DG1021 650 795 Logic Analyzer ZeroPlus Intui
78. 2H conversion appli cation posted on the Circuit Cellar FTP site and detailed in Cypress Semiconductor s application note AN13945 I created byte arrays to insert into the mixer project I then piggybacked the playback loop on the ADC polling I simply ignored the incoming samples and instead streamed from an array Now when the unit changes modes it speaks RETAIN USER SETTINGS Suppose you wanted the ability to store and retrieve sets of potentiome ter positions from internal flash mem ory at will thus allowing multiple users to save their preferred settings This is possible within the project you have developed thus far You probably realize that you are completely out of I O pins at this point on the PSoC This is true How then will you issue the commands to save and retrieve sets of potentiometer positions registers www circuitcellar com 3itScope USB Mixed Signal Oscilloscope Inventing the future requires a lot of test gear Analog Digital Digital Storage Oscilloscope Dual Channel Digital Scope with industry standard probes or POD connected analog inputs Fully opto isolated Or a BitScope Mixed Signal Oscilloscope Capture and display analog and logic signals together with sophisticated cross triggers for precise analog logic timing Multi Band Spectrum Analyzer Display analog waveforms and their spectra simultaneously Base band or RF displays with variab
79. ACIM is the sim plest and most rugged electric motor It consists of two basic electrical assemblies the wound stator and the rotor assembly The outer stationary stator consists of coils that are supplied with an AC current to produce a rotating magnetic field The inner non stationary rotor revolves as a result of the torque that is created by the rotating mag netic field The induction AC motor derives its name from currents flowing in the rotor that are induced by alternating External resistors H Figure 1 This is a Powerex CM400DU 12F module with an RCD snubber circuit Photo 1 This photo shows the IGBT and gate driver assembly during the testing phase of development Hall effect current sensors are mounted on phase 1 and 3 The snubber board not shown is installed on top of this circuit WWW CIrCUItC currents flowing in the stator You can control the speed of an ACIM by varying the fre quency and amplitude of the drive voltage Early configura tions of drives used SCRs fired at the appropriate times to create an unsophisticated sinusoidal input waveform As the semiconductor industry evolved SCRs were replaced with MOSFET or IGBT devices which are more efficient than the SCR and could be switched at higher frequencies to continuously generate variable drive voltages and cur rents that closely resemble a sinusoidal waveform The AC current that is supplied to the stator which pro
80. AN12 AN12 RB12 E 45V PWRCTL EXTVCC 4 AN13 AN13 RB13 SCL RG2 RG2 POWEREN VCC IO AN14 T1 3 amp N t4 P814 SDA RG3 RG3 gt TXDEN RXLED LZ FAULT AN15 OCFB CN12 RB15 EMUCS SCK1 INTO RFG RF6 Rli SLEEP C15 RD14 ICT CN20 RD14 SDH RF7 RF7 DCD Ground Fs 0 1u RD15 ICS CN21 RD15 UMUDS SDO1 RF8 AGS DSR amp 3V30UT RF4 U2RX CN17 RF4 U1RX RF2 DTR Ground LZ RFS U2TX CN18 RF5 U1TX RF3 CTS RESETO RTS amp RESET 5V Analog test points RxD Ground m E DSPIC30F6010 TXD BOARD ID AN1 Hall 2 ANS IVACI sense AN2 Hall 3 AN10 Phase 4 shunt DLP USB232M AN3 QEI A AN11 VBus shunt AN4 QEI B AN12 VPH1 ANS QEI INDEX AN13 VPH2 ANG Brakes AN14 VPH3 AN7 Speed AN15 Dig nFault b HiHLIN ol i ANO l l H 2IN ANI SWDPDT L1 5V LCDRS LCDR W LCDENAB CAPTURE 1 CAPTURE 2 CAPTURE 3 Position Hall Interface QEI Connector C13 L4 3 3u 0 001u 5V FIRE_ENABLE H15 470 DS6 Red lod MCP2551 PFC_FIRE BRAKE_FIRE 5V 5V 5V PHASE1_LOW PHASE2 LOW PHASE3 LOW PHASE1_HIGH PHASE2_HIGH PHASES HIGH FAULT FAULT FAULT 15V 15V 15V EE Ed P16 MT HT n Figure 3 This is the schematic for the motor control board based Ria bii bias on the motor control board design from Microchip Technology We used Protel to create our schematics and circuit boards Socket Socket Socket www circuitcellar com _ CIRC
81. ARD cost 69 and 59 respectively Starting at 89 the C2000 Experimenter Kits include either the JTAG EMULATOR FOR FREESCALE ColdFire V2 V3 V4 DEVICES The J Link ColdFire BDM 26 a JTAG emulator for Freescale ColdFire addition the J Link ColdFire BDM 26 V2 V3 V4 devices is now available from SEGGER Microcontroller offers high download speeds into the target The J Link ColdFire BDM 26 enables fast and reliable connections system to maximize productivity of valu from the development system to your target hardware Together with able design resources Freescale Semiconductor s CodeWarrior Development Studio or the IAR The J Link ColdFire BDM 26 costs 299 Systems YellowSuite this emulator sets new standards for professional debugging solutions at affordable prices SEGGER Microcontroller The J Link ColdFire BDM 26 offers the big advantage of programming WWW segger com the embedded flash memory directly from the IDE There is no need to exit debugging and use a different tool to program the internal flash In www circuitcellar com CIRCUIT CELLAR Issue 217 August2008 9 NEW PRODUCT NEWS RTOS SUPPORT FOR STM32 FAMILY You now have the opportunity to combine the efficien cy flexibility and scalability of the RTXC family with the high performance quick time to market STMicroelectron ics STM32 family This combination of software and hard ware brings new degrees of freedom to the MCU market because it offers the best of
82. CK OUT CLOCK F and even 2 F F and 2 OUT CLOCK OUT F F and more The respec CLOCK OUT tive amplitudes of these image fre quencies follow a curve mathematical ly defined as sin x x which happens to be the Fourier transform of a single step of width 1 F cock But there is another problem When your output frequency goes higher and higher the power of the image frequencies gets higher too Power needs to be found somewhere This implies that the power of your desired Four signal becomes lower and follows the same sin x x curve shown in Figure 5 This leads to two problems One you need to know and compensate for if necessary the reduction of signal amplitude when the frequency goes closer and closer to the Nyquist limit at which point the theoretical power reduction is 3 92 dB Two when you come close to this limit the first image frequency which you need to cancel out with the low pass filter comes clos er to your desired frequency and worse at a similar amplitude Because the required low pass filter would be impossible to build you can t actually generate a signal arbitrarily close to the F 2 limit see Figure 6 The usual reasonable limit is around 4096 of P even with sharp filters www circuitcellar com However nothing prevents you from using one of these image frequencies instead of the fundamental Just replace the low pass filter with a band pass fil ter and you can
83. Course CCS Keil IAR Boost C amp Hi Tech www r 4systems com CIRCUIT CELLAR Issue 217 August 2008 63 theory says that the signal to Amplitude total quantization noise power ratio is 1 76 6 02B dB with B as the resolution in bits of the DAC For example with an 8 bit DAC you can expect a 50 dB i e 1 76 6 02 x 8 signal to noise power ratio But that s just an average However there is a trick if the quantization p Second and noise is a problem Because the i d noise is somehow spread from DC to the Nyquist limit you can limit it just with a band pass filter around your frequen cy of interest If you reject all FCLOCK frequencies except a 10 pass band dE bor dh Figure 6 The role of the low pass filter is fundamental It must keep the fundamental frequency nearly untouched but pro an bee OUT oe S vide a high attenuation on all image frequencies That s why straight filters are usually required It is also why the maximum quantization noise will be frequency is usually 40 and not 50 of F divided by 10 Another solution is oversampling If you increase Nyquist Frequency 2 FcLoCK CLOCK P Without increasing the low pass The number of bits in the phase accu broadband noise but discrete spurious filter corner frequency the quantiza mulator register is not infinite fur frequencies on the output spectrum tion noise will be lower in the filter thermore the number P of input bits You
84. EMS sensor three axes of angular rate and three axes of accel eration in a compact and rugged pack age My client wanted to marry an Analog Devices Blackfin DSP chip to it in order to create a self contained inertial measurement solution After a couple of design iterations we came up with the board shown in Photo 1 which holds the Blackfin processor and various interface and power supply components A group of finished units in their boxes is shown in Photo 2 A key aspect of the imple mentation was that the firmware would need to be updated in the field after the unit had left the controlled environment of the factory in order to Photo 2 The sensor PCB and the power l O connector fit into a small custom box which is 3 x 4 x 7 5 cm overall not including the connector The JTAG connector seen on the left side in Photo 1 is not populated in production units 34 Issue 217 August 2008 support both bug fixes to the basic functionality and additional features for specific end user applications This article is about the two stage bootloader that we developed that meets all our requirements and adds some capabilities to the native boot processing of the Blackfin chip While much of this discussion will be specif ic to the Blackfin family of DSP chips some aspects of it are more general and can be ported to other processors BOOTING A BLACKFIN Booting the application code is a multistage process When the Black
85. FDl Future Designs Inc 89 MCC Micro Computer Control 89 Rabbit A Digi International Brand 92 Xytronix Research amp Design Inc Preview of September Issue 218 ATTENTION ADVERTISERS Theme Data Acquisition October Issue 219 Content Acquisition And Display Build An Internet Connected News Ticker Deadlines Universal Machine Control How Proper Hardware Emulation Leads To Prototype opace Close Aug 11 Development Material Close Aug 19 Dynamic Animatronic Remote Part 1 Build A Custom Controller With A Color LCD Theme Fast Digital Filtering Signal Processing Prototyping With QFP Parts BoNus DISTRIBUTIONS ARM DevCon Embedded Systems Real Time Vibration Measurement For Aircraft Conference East LESSONS FROM THE TRENCHES Living And Working Off The Grid Part 2 Installation And Performance Call Shannon Barraclough now to reserve your space FROM THE BENCH Fingerprint Data Acquisition Print Sensing With Embedded Technology 860 875 2199 SILICON UPDATE Embedder Than Ever A Look At New Embedded Technologies e mail shannon circuitcellar com 94 Issue217 August 2008 CIRCUIT CELLAR www circuitcellar com Testgear Owon 25MHz 2 ch trigger standalone USB bench scope with 7 8 color LCD Battery powered optional PDS5022S 25MHz PDS6062T 60MHz 325 599 25MHz 100 MS s 2 16ch scope logic analyzer 5ns 5s div with complex triggering See wfm data lines 7 8 TFT Color LCD USB connected 4MS bu
86. ITS RF Modules Low Cost TX RX 2 within the data portion of the CAN bus packet This would be a disadvantage in more complex systems because all bus traffic is picked up by all nodes To reduce microprocessor overhead in these designs use the filters to receive only those mes sages required for processing by the specified node The CAN bus protocol also has error detec tion accomplished by the following methods monitoring transmitters compare the bits to be transmitted with the bits detected on the bus cyclic redundancy check CRC bit stuffing and message frame check Because the CAN bus protocol handles most of the error checking and timing issues we did not need to introduce elaborate error handling algorithms We simply added headers and check sums to the data that is sent in a function called Sliders see Listing 2 This function assem bles and sends the PID tuning parameters and waits for an acknowledgment package ACK or NAK from the motor control microcontroller when the parameters are received before taking any further action FIRMWARE SOFTWARE The daughter board firmware is responsible for assembling CAN bus packets and sending and receiving messages Currently the only WIRELESS BRING YOUR PRODUCT QUICKLY AND LEGALLY TO MARKET Add INSTANT wireless analog digital capability ta your product Multi Channel Modules hi RS A fa TT As low as Two Boards Two Layers 9 95 L each One Le
87. OUT Spectrum Spectrum mandatory output low ass filter all harmonics P Figure 5 This Scilab simulation shows the phase output signal and output spectrum of a 16 bit DDS clocked at 1 GHz with two dif uh the Nyquist limit of ferent tuning words F y 78 MHz on the left and 239 MHz on the right The amplitude of the fundamental frequency gets lower Food 2 will be filtered out hen the frequency increases following a sin x x curve dark blue and image frequencies get more powerful and unfortunately So for non sine signals you closer to the desired frequency 62 Issue 217 August 2008 CIRCUIT CELLAR www circuitcellar com some examples later on WHO SAID sin x x You have now discovered all of the key advantages of a DDS architecture but what are the difficulties that you may encounter First you have to look at the low pass reconstruction fil ter again Why do you need it Because the output of the DAC is not a sine signal but a succession of steps that match a sine curve only at the clock edge events even if you assume that there are no other sources of error elsewhere In the frequency domain this means that the spectrum of the output signal will not be a simple fun damental E but a more complex signal I used SciLab a Matlab like open source tool for a simulation see Figure 5 There are image frequencies in the output You get not only the frequency F but also F FF and F OUT CLO
88. Pots button is being held The mixer speaks For example it will say Writ ing 1 when storing Set 1 When retrieving Set 1 it will simply say 1 The serial terminal reflects the I used standard female RCA jacks as I O because of their size cost and compatibility I had ExpressPCB draw the schematics lay out the PCB and run netlist checks between the two A view from the PCB editor for this pro ject s circuit board is in the Printed Circuit Board Layout doc file on the Circuit Cellar FTP site If you are familiar with ExpressPCB please note that this all fits into the inexpensive MiniBoard service I included an in system program ming ISP connector It is standard practice with my designs because Listing 1 Here is the code used to handle the two button inputs It determines whether the Mode button has been tapped or is held as well as when both buttons are simultaneously pressed This provides multiple user input functions with only two buttons while 1 DoEvents if CheckKnobEnableButton 1 ButtHoldCount 0 check for a tap or hold here ButtHeld 0 while CheckKnobEnableButton amp amp ButtHoldCount lt ButtHoldDelayCycles 1f ButtHoldCount gt ButtHoldDelayCycles ButtHeld 1 if ButtHeld while CheckKnobEnableButton 1 ScanPots if GainChangeThisCycle UpdateAllGains GainChangeThisCycle 0 SendSerialNextChance 1 1f SerialOutputCounter
89. Security donge needed Visit www hexwax com today Amazing PIC programmer Most devices supported ICSF SOTP amp copy limits at Digikey A 1 32 amp Mouser E E www flexipanel com Issue 217 August 2008 Actual size patents pending 91 T writes your USB Code NEW Creates complete PC and Peripheral programs that talk to each other over USB Ready to compile and run x Large data Reports 64 000 bytes sec per Interface Easily creates devices with multiple Interfaces even multiple Identities Automatically does MLILTITAS KING Makes standard or special US B HID devices NEW Developers Guide for USB HID Peripherals shows you how to make devices for special requirements HiOmaker FS for Full Speed FLASH PIC18F4550 Both PC and Peripheral programs understand your data items even odd sized ones and give you convenient variables to handle them PIC18F Compilers PICBASIC Fro MPASM C18 Hi Tech C PIC16C Compilers PICBASIC Pro MPASM Hi Tech C CCS C PC Compilers Delphi C Builder Visual Basic 6 HIDmakar FS Combo Only 588 35 DOWNLOAD the HiDmaker FS Test Drive today CONNECT TO SMT PADS BGA QFN MLF IC SMT Pads Become QFP Connection Interface with SMT Emulation Industry s widest selection for SMT Pattern Interconnect Technology allows Test Prototype Package Conversion Emulation Quick Custom Designs for all package types Ironwood Electronics 1
90. UIT CELLAR Issue 217 August2008 25 Photo 3 This shows the interconnections between the motor control board and the gate drivers on the inverter Shielded cable was used to reduce EMI The most significant difficult aspect of the board design process involved trying to anticipate the needs of future users The board was given more CAN bus connectors than the standard MCI board We included two DE 9 connectors instead of one as well as four custom sockets for additional CAN bus modules The final connection between the con trol board and the inverter is shown in Photo 3 A daughter board was created to assist in debugging as well as provide an interface to the LabVIEW application used for motor tuning and instrumentation see Photo 4 An alter nate version of Photo 4 with callouts is posted on the Circuit Cellar FTP site The daughter board acts as a bridge between the CAN bus and the USB with robust error checking between the two protocols The daughter board microcon troller and the CAN bus controller were left with separate clocks due to the timing sensitivity of the CAN bus With some minor modifications the module could also control an optional LCD The module connects to the main board with a four pin connector that also provides power to the mod ule Four of these sockets are provided on the main board SPACE VECTOR MODULATION AC induction motor ACIM control can be accomplished using many techniques For our project we
91. WO091E 99 INDIID MMM MCU Based Filtration Monitoring p 52 Design amp Program A USB Virtual COM Port p 70 New Developments In Soft Core Technology p 78 CIRCUIT CELLAR THE MAGAZINE FOR COMPUTER APPLICATIONS 217 August 2008 EMBEDDED DEVELOPMENT Two Stage Bootloader Development Electric Vehicle Inverter Build A DMX Lighting Controller Direct Digital Synthesis Explainec Enhance Your Single Chip Apr IR Distance Measurement WII o 74470 75349 9 g c i 5 95 U S 6 95 Canada Lone F SERIAL TO ETHERNET SOLUTIONS a T Device P N SB70 100CR Kit P N NNDK SB70 KIT S69 870 Oty 100 pod serial to Ethernet server with TTL support Device P N SB72 EX TOOCR i Kit P N NNDK SB72EX KIT SB72EX 139 2 port serial to Ethernet server Qty 100 with RS 232 amp RS 485 422 support Device P N PK7OEX 232CR Kit P N NNDK PK70EX232 KIT 26 Q PK70EX232 4 port serial to Ethernet server Oty 100 with RS 232 support Simple Ethernet connectivity for serial devices Works out of the box no programming is required Customize to suit any application with low cost development kit Features 10 100 Ethernet TCP UDP mode DHCP Static IP Support Data rates up to 921 6kbps Web based configuration Need a custom solution NetBurner Serial to Ethernet Development Kits are available to customize any aspect of operation including web pages data f
92. amples med channel storage l 100 MSamples sec Battery option The complete sequence Zooming in on one byte USB or ethernet e e e e Data projector display The CS328A is an engineer s toolbox Oscilloscope Tracking Graph Spectrum Analyzer Protocol Analyzer Multimeter Logger Result Storage Maths Equation Builder and Display Function Generator Simple cut and paste XY Graph Drivers for C Dephi and Labview into documents Custom Names Units and Scaling clever plug amp play instruments WWW cleverscope com Regular software and firmware updates Embedded Single Board Computers High End Performance TS 7800 with Embedded Ruggedness 500 MHz ARM9 Low power 4W a BV 128MB DDR RAM 512MB high speed 17MB sec onboard Flash ty 12K LUT programmable FPGA Internal PCI Bus PC 104 connector 2 host USB 2 0 480 Mbps Gigabit ethernet a 2 SD S s 10 serial ports 110 GPIO i 5 ADC 10 bit vd 2 SATA pc rts Sleep mode uses 200 microamps TO and backward compatible with TS 72xx Boots Linux in 2 seconds Linux 2 6 and Debian by det ault Low Price Low Power High Heliability 200 MHz ARNG using Linux development tools Power as low as 1 4 Watt B boards over 2000 configurations s r Compact Fas Fanless no heat sink ni SDRAM up to 128MB Flash up to 128MB onboard 10 100 Ethernet up to 2 DIO lines up to 55 SD card ation VGA v video LCD ready
93. anage up to 63 concurrently executing tasks structured as state machines QP C and QP C can also work with a traditional OS RTOS to take advantage of existing device drivers communication stacks and other middleware QP has been ported to Linux BSD Windows VxWorks uC OS II and other popular OS RTOSs 8 Quantum f amp aPs PRACTICA UML STATECHARTS secure Edibios Esmi D poaz Pragrariming tar EMD S LGT QP is available for immediate down load under the GPL version two open source license Alternatively QP can also be licensed under the terms of tra ditional closed source licenses which expressly supersede the GPL and are L specifically designed for licensees interested in retaining the proprietary status of their code Single product commercial licenses cost 995 1 995 and 2 995 for QP nano QP C and QP C respectively Product line and custom licenses are available as well Quantum Leaps www quantum leaps com PROGRAMMABLE LOGIC STARTER KIT The MACH64 Programmable Logic Starter Kit takes you from mystery to mastery in the black art of CPLDs CPLDs are great starting points if you are interested in programmable logic technology They enable you to seamlessly move into their bigger brothers FPGAs when you re ready The power of CPLDs is that with a software based tool you can write code that is compiled into a hardware description that is then downloaded and flashed into the CPLD
94. and PIC18F4620 microcontroller Microchip Technology Inc www microchip com CM400DU 12F Transistor module VLA106 15242 DC DC converters and VLA503 01 gate drivers Powerex Inc WWNW pwrx com C Embedded amp Network h onmi Technologies 1 Wire Spi R 232 2C Micro D Spi RTC WiFi Micro 5D RTC e L i T ur i amt E Issue 217 August 2008 31 s rch TR Ai x ont 1189 Com Wet e lecues T jot si th ey appen i 7 i len he E SBI LL g i F LAL CEEE aii EM III J LTE k aded LJ Pease L s mad ne P S Po EN N TE CET ee ee ac ee i G a15 On aii OF OUF APCOIVes VISIT W ww circuitcellar com archives CIRCUIT CELLAR Designer s Notification Network Circuit Cellar design contest entrants have received thousands of valuable development tools and product samples Because of their contest participation these engineers receive advance e mail notice from Circuit Cellar as soon as new samples become available Now you too can benefit from this early notification Welcome to the Designer s Notifica tion Network Print subscribers are invited to join the Network for advance notice about our new sample distribution programs Find out more at www cir cuitcellar com network Microchip Technology 1 CON TY If you need Full Speed USB 2 0 Device Embedded Host Dual Role and ST TL Zone On The Go solutions you re in the right place Circuit Cellar is pleased to launch the Microchip Technolo
95. and spectra real time or capture mixed signal data to disk Comprehensive integration means you can view analog and logic signals in many different ways all at the click of a button The software may also be used stand alone to share data with colleagues students or customers Waveforms may be exported as portable image files or live captures replayed on another PC as if a BS100U was locally connected retrieved settings HARDWARE PCB i La i Lb i Lc i Ld i Ra i Rb i Re i Rd L i R i LR Mic 4 06 1 1 06 11 06 11 06 11 06 1 1 06 11 06 11 06 1 1 06 1 1 061 1 06 1 14 i La i Lb i Lc i Ld i Ra i Rb i Re i Rdi L i R i LR i Moi RTE RE RLRE 1133113 113 1 131 1 491 1 28 Figure 3 These are new serial terminal output examples for reverb top and pitch shifting bottom Well you already have two but tons They are being used independ ently as well as without any type of tap hold logic in place How about this A quick tap of the Scan Pots button will retrieve and cycle through the sets of potentiometer readings while holding this button will result in normal adjustment operation with the potentiometers active Then if the Mode button is pressed while the potentiometers are active the current potentiometer readings are written to the current Set The resultant C main loop code that handles this overall logic is shown in Listing 1 That logic handles all of the issues that arise with the suggest
96. ar RE TID _ NR pm tal SS E i Draai lom t aj sam m ma el a E naz m WwWwWw usbee com TEJ DX Bnalcg i G 10V Max I El XEM AS O CON www circuitcellar com CIRCUIT CELLAR power of the largest spur is around 6 02 P dBc with P being the number of phase bits after truncation The dif ficulty is that the count frequencies and amplitudes of these spurious sig nals are dependent on both P and the phase increment value W If you change the selected DDS frequency a little the spurious frequencies will be drastically different see Figure 8 p 67 This behavior makes life for a DDS designer a little more complicated but it is also a potential friend If you have some flexibility in the DDS parameters for example and if you can have a slightly different Fu or Fouy then you may find another com bination that gives fewer spurious fre quencies or at least less fewer spurs in a given frequency band The good news is that the behavior of the DDS is predictable and some good simula tion tools are available from chip manufacturers There are other sources of noise in DDS clock jitter DAC nonlinearity clock feed through and more but image frequencies DAC quantization Issue 217 August 2008 65 and phase register truncation are usu ally the main contributors However don t conclude that DDS generates only noisy signals These problems exist but a good
97. aseT Ethernet SODIMM Bus Expansion SC I2S Audio Interface Real Time Clock Calendar EL LL CP MH s e nner Loi x Ho ine 2007 HHIHH HIHIH s SD MMC Flash Card Interface Up to 64 MB Flash amp 128 MB RAM e Linux with Eclipse IDE or WinCE 6 0 2 USB 2 0 Host Ports amp 1 Device Port 4 10 Bit A Ds amp 6 16 Bit Timer Counters Small 144 pin SODIMM form factor 2 66 x 1 5 2 6 Kernel Optional Carrier Socket Board amp Power Supply Available he SoM 9260 uses the same small SODIMM form factor utilized by other EMAC SoM modules and is the ideal processor engine for your next design Volume Discounts PETELE i gridconnect www gridconnect com 1 800 975 4743 www circuitcellar com CIRCUIT CELLAR All of the ARM9 processor core is included on this tiny board including Flash Memory Serial Ports Ethernet 125 Audio Interface PWMs Timer Counters A D digital I O lines Clock Calendar and more Like other modules in EMAC s SoM product line the SoM 9260 is designed to plug into a custom or off the shelf Carrier board containing all the connectors and any additional UO components that may be required The SoM approach provides the flexibility of a fully customized gar OPUS a greatly reduced cost Single unit pricing starts at 150 Kx ENA inc EQUIPMENT MONITOR AND CONTROL SINGLE BOARD SOLUTIONS Phone 618 529 4525 e Fax 618 457 0110 Web www emacinc com Issue
98. ash File ULINK 2 Adapter for target debugging and Flash programming Qut of the box support for more than 1 400 Microcontroller devices www keil com Issue 217 August 2008 17 possible to starve the DMX j refresh process of execution time If this happened and the DMX process was not blocking the system might not have met the minimum DMX refresh rate and some lights could have gone into Auto Shut down mode Different applications are likely to have differing require ments for priority given to DMX output and com mand processing but you can modify the code to suit your needs WORK WITH THE W5100 The W5100 was a good fit for this project because implementing the software required for a simple TCP IP stack with assembly would have been a time consuming task The W5100 handled all of the details and required me to write only a few sub routines to read from the device and calculate offsets into the chip s buffer memory to find my data Some of these calculations required 16 bit math which is not natively supported by the PIC18F family Luckily I had already written a library of basic 16 bit math functions for use with the com mand processor The firmware stores all of the con figuration parameters such as the IP address gateway subnet mask and MAC address in the internal EEP ROM so they can be used to configure the W5100 during power up These parameters can be modified via the ASCII comma
99. automatically compensate for the sin x x amplitude rolloff I discussed earlier with a digital filter that has an inverse sin x x response placed between the look up table and the DAC You can program eight different settings for fre quency phase and amplitude and then switch among them in nanoseconds via three external pins If necessary it can also automatically manage linear frequency phase or amplitude sweeps In addition it has a built in 1 024 x 32 RAM that enables you to predefine cus tom frequency phase amplitude pro files and execute them at high speeds which is perfect for generating complex no more than 5 5 mA at 3 V which is impressive for a 25 MHz chip Techni cally speaking it has a 28 bit phase reg ister a 12 bit look up table and a 10 bit DAC which provides around 60 dB of signal to noise ratio Now you will easi ly understand such a datasheet Now let s focus on a current top of the line DDS chip The Analog Devices AD9910 depicted in Figure 9 is nearly 10 times more expensive than the AD9833 It costs around 35 qty 1 000 as I write this But what a piece of silicon First its clock can be as high as 1 000 MEZ providing a useful output range up to 400 MHz Providing a 1 GHz clock may be difficult but these guys had the good idea to include an on chip PLL to allow more reasonable external clock sources Its 32 bit phase accumu lator provides sub hertz resolution and it is equipped with a h
100. b to maximum will result in approximately 200 ms of reverb delay Slower sampling rates will fill this limited buffer slower resulting in more delay Faster sam pling rates will result in less delay see Table 1 As a side note using the 7 5 bit res olution 64x decimation rate setting results in a 15 6 kHz sample rate and the frequency response increases accordingly However this results in CIRCUIT CELLAR roughly half the maximum reverb delay which is barely noticeable and not nearly as fun to play with So 7 8 kHz it is With some external memory and perhaps a larger package PSoC with more I O pins higher sampling rates and longer reverb delays this method becomes usable The PSoC is also filtering the ADC samples as they arrive through an optimized infinite impulse response IIR filter algorithm The algorithm counters some sampling noise by not allowing sharp spikes through This requires no digital or analog blocks to implement whatsoever and is prefer able in this case over a standard low pass or band pass SC filter module You may be wondering why a 0 delay is listed in Table 1 as shifting the output 170 us from the input This is the minimum time it takes for a sample to be fed through the software only filter and through the FIFO buffer The unused control knob RP is used to adjust the reverb delay time The new schematic is shown in Figure 1 A flowchart of the reverb algorithm is shown in Fig
101. better if the alternative standard MCU comes with even more features you don t need The lesson is that when you compare a soft core to a standard chip make sure you compare apples the standard chips you can choose from to oranges a soft core crafted with exactly and only the features you need TOOL TIME Top Ten Predictions from the IEEE Field Programmable Custom Computing Machines FCCM Conference 1996 1 We will hate the tools 1998 1 We will still hate the tools 2000 7 We will merely dislike the tools 2007 10 We hate the tools more Source www fccm org top10 php I guess you could call that progress www circuitcellar com So far I ve been talking about the Cortex M1 soft core and the FPGA chips it runs on In my opinion the combination is pretty compelling now and will only be more so in the future Nothing fancy at all about Cortex M1 And that s a good thing Performance ranges from 24 MHz Igloo at 1 2 V to 66 MHz ProASIC and Fusion which is more than adequate for many blue col lar applications At the same time the i i N F id RI HII m BI ES Ta 7 5 x la L l c titt a p M1 is lean enough to pass a price per formance and power consumption reality check The Thumb plus or Thumb 2 minus Call it Thumb 1 5 architecture gets a free ride on the ARM bandwagon On the silicon front all FPGAs continue their march towards mass markets
102. cal yawn inspiring blizzard of tiny text cryptic symbol names and hard to decipher runes like 0x1AC543D7 Who says this embedded biz has to be so drab and boring Let s live a little Photo 1 Check out the uC Probe in action make a key point about the soft core debugged and in production do you real MI you can leave the fancy debug concept and apples and oranges When ly need to ship a debug engine to each stuff off the production units perhaps evaluating the soft core versus hard end user Unlike a standard MCU with relying on a simpler scheme if you core trade off the perspective tends to be how close e g price performance power the former can get to the latter MELIUS a There s some insight to be had with ks a e a that perspective but also the trap of aol comparing apples to apples Let s stipulate that if there is a nice crisp standard MCU i e one apple that perfectly matches your applica tion it will no doubt taste better than a mushier FPGA soft core based solu tion i e the other apple It s to the degree that a standard chip l d p smartrime 34 isn t a perfect fit that the window opens T LS srt i fo MILI for soft core That s evermore likely the NEM tier greer MP iim L case as kitchen sink MCUs incorporate any and every popular I O and glue func tion Yes it s nice to be able to buy a chip with everything you need and then some but don t forget
103. ce one from a mirror on the target then combine them to form an interference pattern The pattern varies from bright to dark to bright with distance so meas uring the intensity and counting peaks give a resolution in microns This obvi ously works best for stationary objects and has a nasty sensitivity to vibration Measuring the intensity of light reflected from an object provides a less accurate and more compact distance measurement because all else being equal a more distant object will be dim mer and a closer object will be brighter Unfortunately all else is rarely equal Intensity sensors generally use infrared light because IR s longer wavelength makes objects more reflec tive and perhaps for the simple rea son that IR isn t visible Most visible light sources also emit plenty of IR all CIRCUIT CELLAR Photo 1 Greg s chord keyboard has one modified push button switch at each fingertip and three for the thumb He can reach below the key arch to get a more or less normal grip on objects that ambient light reaching the sensor whether reflected from the object or not adds to the measured intensity and reduces the apparent distance The object s reflectivity sets the upper limit of light available at the sen sor a dull black object reflects far less light than a shiny white object at the same distance and will thus appear to be farther away Not surprisingly an object s visible light reflectivity ra
104. circuitcellar com I www tibbo com sales tibbo com ri Reset Si H1 39k sy C2 a R3 470 C1 10n MCLR 45V PFC FIRE 7 PWMSH RES PWM3L RE4 BRAKE FIRE R8 lt Rg S PWM4L REG PWM2H RE3 PHASE3 HIGH T K 4 Tk PWM4H RE7 PWM2L RE2 PHASE3 LOW LCDRAW T2CK RC1 PWM1H RE1 PHASE2 HIGH 4 LCDRS TACKIRC3 PWMHL REO PHASE2 LOW SCK2 CN8 RG6 C2RX RGO PHASE HIGH S2 __ SDI2 CNS RGT C2TX RG1 PHASE LOW g sbozicni nes CATX RF1 SE L K KS eure R44 R51 SS2 CN11 RG9 45V 4 7k S4 all as R4 47k v S8 FN YER R43 4 7k gt aa OCBS UPDN CN16 RD7 an 45V 1 7 FLTAJINT RES OC7 CN15 RD6 FAULT RESET FLTB INT2 RE9 OC6 CN14 RD5 2 AN5 pte ANS aEB CN7 RBS OC5 CN13 RD4 S del AN4 IH ral IC6 CN19 RD13 LCDENAB LED1 LED LED3 LED4 LED6 AN3 a ANSINDX CNS RBS IC5 RD12 LCD BLIGHT AN2 5 L cN4mE2 OCA RD3 LCD3 AN1 p L OC3 RD2 LCD2 b e E a s ANO ST 8D EMUD ANO CNZ RBO EMUD2 OC2 RD1 LCD1 ANG Ha Ne ocFA RBe EMUC1 SOSCO TICK CNO RC14 SOSC1 ANT 55 ANTIRBT EMUD1 SOSCI CN1 RC13 SOSC2 FIRE ENABLE LED1 1 24 REF RAQ EMUC2 0C1 RDO LCDO x DS1 DS2 DS3 DS4 DS5 B i LED2 REF RA10 ICA RD11 L A E E r1 45V ERES ICS RD10 CAPTURE 3 A 5 AVDD IC2 ADS CAPTURE 2 c3 S E AVSS IC1 RD8 CAPTURE 1 sU me uris Me A AVE sy AND e 25 Y1 AN10 1 29 VSS 7 3728MHz EM DST AN11 dj d I 0 X F USB Activity Ex is T VDD 5V 33p 33p TXLED PORTVCC m
105. comparator to extract a square signal with the same frequency kind of modulation still fully in the will be limited to output frequencies There are a lot of other possibili digital domain Refer to Figure 4 low enough to ensure that all har ties thanks to the digital structure of which shows a little enhanced DDS monics required for a good genera a DDS and silicon makers are imagi architecture With a DDS you can tion of your signal are significantly native in these areas You will see easily change the output frequency on the fly with out any delay or phase shift just by loading a new value Phase N 16 P 16 B 8 W 5 169 Phase N 16 P 16 B 8 W 15 673 in the phase register or nee switching between different So coe phase registers for FSK like 40 000 transmissions You can j 30 000 also add a fixed value to 20 000 the phase register inde biag pendently from the DDS 0 5 10 15 20 25 30 35 40 45 50 0o 15 20 25 30 35 40 45 50 itself which is ideal for phase modulation or PSK You can add a digital mul tiplier before the DAC to implement software con trolled amplitude or AM modulation You can generate wave forms other than sine just by loading a period of your designed signal in the look up table But in that case be careful because you will be drastically lim ited in terms of maximum frequency Due to the 500 1 000 1 500 2 000 2 500 3 000 500 1 000 1 500 2 000 2 500 3 000 FOUT F
106. conversion of a gasoline engine to an electric motor Currently the main factors in conversion are safety and battery technology As these concerns are addressed an open source project will be a welcome alter native for those who wish to take on an electric motor modification themselves Dan Hall is a recent Camosun College graduate with a diploma in Electronics Engineering Technology You may contact him at dan je hall gmail com Tristan Kasmer is an engineering technologist from Camosun College He currently lives in Victoria BC and is pursuing activities in alternative energy and control systems You may contact him at tristankasmer hotmail com Doug Krahn is a recent Camosun College graduate with a diploma in Electronics Engineering Technology He 30 Issue 217 August 2008 CIRCUIT CELLAR works for the Canadian Department of National Defense You may contact Doug at dougkr telus net Adam McIntyre is a recent Camosun College graduate with a diploma in Electronics Engineering Technology He is continuing his studies at the University of Victoria You may contact Adam at a_mcintyre shaw ca Dena Ponech is a recent Camosun College graduate with a diploma in Electronics Engineering Technology She works for the Canadian Department of National Defense in Marine Engineering Systems You may contact Dena at denaponech hotmail com PROJECT FILES To download code and additional files go to ftp ftp circuit cel
107. d Autorouter 498 996 Layout Editor and Schematic Editor 747 and Autorouter 1494 800 858 8355 Cadsoft Computer Inc 19620 Pines Blvd Suite 217 Pembroke Pines FL 33029 Hotline 954 237 0932 Fax 954 237 0968 E Mail info cadsoftusa com 58 Issue 217 August 2008 CIRCUIT CELLAR and the level of the water height green LED boards bytes are in the chain Each PCB has its own parallel to serial shift register The serial shift register bus contains five signals 5 V SDA SCK load and ground All eight parallel input bits are sampled using the load control line The inputs can then be shifted out using a SPI or in this case the lines are bit banged All Hall effect outputs are high 1 unless they are sensing a magnetic field Then the out is pulled low 0 The data is read most significant bit to least significant bit and refers to sen sors positioned at 31 down to 0 using four sensor boards and requiring 4 bytes A TINY APP FOR ATINY MICRO This tiny application is written for a tiny microcontroller At less than a buck these eight pin and six pin devices can be used for many interest ing projects However because they are inexpensive they generally don t have many of the peripherals that larg er devices have The eight pin Microchip Technology PIC12F510 microcontroller I used for this project does not have SPI support so the seri al shift routine must be software driv en see
108. d in the SPI EEP ROM but the present scheme uses just three with predefined starting addresses of 0x00000 0x20000 and 0x40000 The image at 0x00000 is always the first one loaded usually when the IMU is manufactured This can be accomplished by program ming the EEPROM before it is installed on the board or by using the Blackfin s JTAG interface and the loader utility built into the IDDE tool chain Updates applied in the field are loaded at 0x20000 or 0x40000 based on a simple toggle algorithm Before beginning a firmware update the application code examines the value stored at offset 26 0x00014A If this 38 Issue 217 August 2008 value is equal to 0x20000 the next update gets loaded at 0x40000 Other wise the current value is either 0x00000 or 0x40000 the next update gets loaded at 0x20000 The firmware update message pro tocol includes several layers of error checking and recovery Each data message is protected by a checksum and once the entire loader file has been transmitted a checksum over the entire image is separately calcu lated If any errors are encountered the entire process can be restarted without any risk to the system When a firmware update is com pleted the last thing that happens is that locations 26 29 in the EEPROM are updated to point to the new image This operation is the only step in the entire process during which a problem e g a power interruption could leave th
109. d loop control able from Microchip The main motor control scheme is executed at a Mieher level inm Fike language in a file called ACIM c posted on the Circuit Cellar EPP site From ACIM c you can manipulate almost every aspect of the motor behavior see Listing 1 ACIM c contains a function called doControl which is executed on a time based interrupt vector This is where you would make alterations to the code in order to make the motor perform differently For our project we needed to get the motor to respond to input the same way that a car would Some of our col leagues needed to introduce regenerative braking into their software This was all done within the DoControl function However you cannot allow too many instructions to occur within this function otherwise the SVM period may become altered and impede proper operation HMI The human machine interface HMI for this proj ect is a LabVIEW 7 1 application built to communi cate with the controller area network CAN bus module over serial over USB protocol by Future Technology Devices International We used the 28 Issue 217 August 2008 ReadSignedADCO amp ReadADCParm Set reference speed if uGF bit ChangeSpeed CtrlParm qVelRef else ReadADCParm qADValue 8 CtrlParm qVelRef ReadADCParm qADValue 16 if uGF bit OpenLoop QPENLOOP force rotating angle Vd Vq if uGF bit ChangeMode just changed to openloo
110. dros Systems Inc www quadros com OFDM BASED POWERLINE COMMUNICATION MODEM The MAX2990 is a new orthogonal frequency division multiplexing OFDM based power line communication PLC modem This device employs advanced broadband communication techniques to deliver cost effective two way data communication over AC and DC power lines at speeds up to 100 kbps By using existing power lines it reduces the need for external cables to interconnect between network nodes The MAX2990 complies with international power line signaling regulations including CENELEC FCC and ARIB This highly integrated SoC is ideal for applications requiring high data rates over long distances such as automatic meter reading energy management and load control lighting control and building industrial and home automation The MAX2990 uses OFDM technology with DBPSK modulation and forward error correction to provide robust data communication in the presence of narrowband interferers group delays jammer signals impulsive noise and frequency selective attenuations Consequently the MAX2990 is the industry s only broadband PLC chip that transfers data at the 10 Issue 217 August 2008 CIRCUIT CELLAR 10 to 490 kHz frequency range Advanced networking techniques ensure a reliable highly secure communications network Specifically a CSMA CA scheme controls the data traffic flow in multiple nodes dis tributed networks and an automatic repeat
111. e s Law has had a huge impact FPGA gates will never match real ones but as the differ ences shrink at some point they become less than material for a particu lar application This month I m looking at a solution from Actel and ARM that makes the soft core concept more viable than ever for new applications maybe even your own Actel s contribution comprises their intriguing flash memory FPGA line up including ProASIC speed and density Fusion analog and bulk flash and this month s chip de jour Igloo low power Moore s Law has done a good job when it comes to making chips including FPGAs faster and cheaper But until recently the power side of the equation has just gotten worse with the march of leaky silicon For now there s a brute force way out namely cutting the supply voltage in the case of Igloo to www circuitcellar com External interface Memory interface Register file Multiply M we fa AHB PPB Shift Logic unit Add AHB Master Load Figure 1 As delivered with Actel FPGAs the Cortex M1 includes a 32 bit three stage pipelined core as well as a standard bus interface AHB Lite and an interrupt controller NVIC A Harvard dual instruction data bus architecture with tightly coupled memories boosts performance 1 2 V Igloo also includes specific power saving embellishments such as a Flash Freeze mode that preserves the internal state and keeps the I O pins alive w
112. e DDS is no longer on the darker side for you lal Author s note I want to thank Lab center Electronics and its U S and French distributors R4 Systems and Multipower respectively who were kind enough to provide me with a Proteus VSM license for this project Also thank you to Jeff Keip and Eric Benoist at Analog Devices who were more than helpful as usual Robert Lacoste lives near Paris France He has 18 years of experience work ing on embedded systems analog designs and wireless telecommuni cations He has won prizes in more than 15 international design con tests In 2003 Robert started a con sulting company ALCIOM to share CIRCUIT CELLAR his passion for innovative mixed sig nal designs You can reach him at rlacostegalciom com Don t forget to write Darker Side in the subject line to bypass his spam filters PROJECT FILES To download code and additional files go to ftp ftp circuitcellar com pub Circuit Cellar 2008 217 REFERENCE 1 Agilent Technologies Inc Agilent 33220A 20 MHz Function Arbitrary Waveform Generator Data Sheet 2005 RESOURCES Analog Devices Inc A Technical Tutorial on Digital Signal Synthesis 1999 www analog com UploadedFiles Tutorials 450968421DDS Tutorial rev12 2 99 pdf K Gentile D Brandon and T Harris DDS Primer Analog Devices Inc 2 003 www ieee li pdf viewgraphs dds pdf SOURCES 33220A DDS Based lab
113. e IMU in a nonfunc tional state Once this step is com plete the next reboot of the IMU will load the new application code Note also that regardless of the value of this pointer the INIT block and the boot kernel that are used are always the ones starting at address Ox00000 because this is hard coded into the Boot ROM The only way to update the INIT block or the second stage boot kernel is to use the JTAG inter face to store a new loader file at offset 0x00000 in the EEPROM When the second stage boot kernel finally executes it examines locations 26 29 in the EEPROM in order to get a pointer to the current application image This pointer contains the address of the beginning of the image including the INIT block and the boot kernel itself so at this point the boot kernel must skip these items using the information in the IGNORE blocks before it can begin loading the application START YOUR DESIGN The archive for this article on the Circuit Cellar FTP site includes the source code for the original Blackfin Boot ROM and our boot kernel for com parison It also includes the INIT block It does not include the application code for the firmware update func tion but if you would like assistance CIRCUIT CELLAR in this area feel free to get in touch with me We have found this system to work very well in practice and an OEM who is using the IMU in a larger embedded system has successfully implemented
114. e decoding but the geek points would be essentially infinite l Ed Nisley is an EE and author in Pough keepsie NY Contact him at ed nisley ieee org with Circuit Cellar in the subject to avoid spam filters PROJECT FILES To download code go to ftp ftp circuit cellar com pub Circuit Cellar 2008 217 RESOURCES Analog Devices Inc Active Filter Synthesis A Simple Tool for Designing Active Filters Using Voltage Feedback Opamps www analog com Analog_ Root static techSupport design Tools interactiveTools filter filter html Background on Chord Keyboards and Keyers Chorded keyboard CIRCUIT CELLAR Wikipedia http en wikipedia org wiki Chorded keyboard P C D Hobbs Photodiode Front Ends The REAL Story Optics amp Pho tonics News Optical Society of Ameri ca April 2001 http users bestweb net M Holm Olsen SpiffChorder USB Keyboard Project http symlink dk projects spiffchorder Morse Code Keyboards www makoa org jlubin morsecode htm and www westest com darci usbindex html E Nisley Foolish LED Tricks Cir cuit Cellar 177 2005 IR Sensing Circuit Cellar 157 2003 LED Optics Lights Diodes Current Math Circuit Cellar 183 2005 Op amp and Analog Circuitry The Audio Pages Elliott Sound Produc tions www sound au com B Pease What s All This Transim pedance Amplifier Stuff Anyhow Part 1
115. e might not work quite as well as you expect AMBIENT LIMIT I aimed a small incandescent bulb flashlight at the wood target and promptly raised the background volt age to 800 mV far higher than the entire signal in the lower trace A simple 250 mV comparator would be ADC input then turn the LED on and measure the level again your program can com pensate for background illumi nation Alas another trade off might make that impossible I picked R1 the feedback resistor that sets the transim pedance gain by taking the breadboard outdoors in direct sunlight The BPV32 photodi ode produced 600 uA of cur rent and I picked R1 for 6 V at the output of UI a reasonable limit for 9 V supplies Remember that no useful sig nal emerges from an op amp jammed at its maximum output voltage In general both the maximum illu mination on the photodiode and the maximum allowable output voltage put an upper limit on the transimpedance gain High ambient lighting and a low amplifier voltage range may reduce the maximum gain enough that the pho tocurrent from the reflected LED becomes immeasurable Single supply op amps used in microcontroller appli cations exacerbate this problem For example an op amp capable of 3 V rail to rail output requires a smaller RI to handle the same ambient light 2 mr Filter Gut 3V RI 5kQ 600 uA 4 The photocurrent that produced the 500 mV change shown in Photo 4 will now pr
116. e port bits for needed signals Typical RS 232 signals used for flow control are RTS and CIS The bridge performs the function of an RS 232 port on the host PC The TX and RTS signals are outputs and RX and CTS are inputs In RS 232 lingo the port is configured as a DTE The RS 232 interface on a PC can connect to a serial port on a microcon troller to another component with a serial interface or via a null modem cable to another PC For cables of up to 4 000 use a full duplex RS 422 interface chip such as a Maxim MAX3087 For a serial network use an RS 485 transceiver in place of the MAX232 If unneeded for modem con trol the RS 232 signals DTR DSR RI and CD can serve as general purpose I O bits or remain unused CUSTOMIZING THE DESCRIPTORS The USB 2 0 specification defines the content and format of standard USB descriptors The CDC specifica tion defines additional class specific descriptors www circuitcellar com Subclass Protocols Interface string index Descriptor size in bytes INTERFACE descriptor type Interface number Alternate setting number Number of endpoints CDC data none none Figure 2 shows the descriptors in a typical CDC device that functions as a generic virtual COM port I ll focus on device specific items you may need to change from values in example firmware Every USB device has a device descriptor see Listing 1 The class code specifies CDC as the device s class The
117. e resultant sample rate is approximately 7 8 kHz Not high fidelity by any means but with some external R C filtering it sounds pretty good It also manages to use the 4 MHz clock already present at every SC block due to the require ments of the mixer for minimal resource consumption As a bonus the DelSig module uses virtually no CPU overhead other than what is used to check for retrieve and use its data So plenty of PSoC processing power is left over between sample cycles The mixer not count ing the adjustment knob scanning requires no processing time It also works passively with the PSoC s hard ware functions DIGITAL AUDIO SAMPLES The DSP output is not a traditional DAC or even a filtered PWM although it is similar in implementation The CIRCUIT CELLAR PSoC has a neat little module called the pseudo random sequence genera tor PRS The PRS module does an excellent job of generating an even distribution of random numbers over a set range It also has a handy output labeled compare out which allows access to a signal that will be high or low based on whether the currently generated number is above or below the compare value At first glance this feature might get passed over without a second thought Let s take a closer look at the compare out signal of a PRS module With an input clock of 12 MHz the PRS module would generate a random compare output at the same rate This output would l
118. e rz R cA Ka d 2 USB ports COM ports up to 10 options include Programmable FPGAs onboard temperature sensor A D Converter 8 channel 12 bit Extended Temperature Battery Backed Real Time Clock USB Flash USB WiFi Linux Real Time extension Debian R Over 20 years in business 3 Custom configurations and designs w 3 Open Source Vision excellent pricing and turn around time a Never discontinued a product P 3 Most products stocked and available a Engineers on Tech Support for next day shipping Design your solution with one of our engineers 480 837 5200 Featured Products and PC 104 Peripherals TS TPC 7390 200MHz ARMS Touch Panel Computer Low Power Industrial Quality Design Mountable aluminum frame s 64 128MB DDR RAM 512MB Flash w Debian Linux Programmable FPGA 5K LUT 7 Color TFT LCD Touch Screen 800x480 customizable video core Dedicated framebuffer 8MB RAM Audio codec with speaker Boots Linux 2 6 in about 1 second Unbrickable boots from SD or NAND Runs X Windows GUI applications Runs Eclipse IDE out of the box TS RELAY8 p TS ADC16 Eight Software Controlled Relays ADC DAC and Digital I O s 8 SPDT relays Software controlled 16 16 bit ADCs Upto277 VAG 5A 40mA draw per coil Upto 100Ksps 10us Up to 30 VDC 5A MO jumpers s 1KB ADC RAM FIFO s 4 ADC voltage ranges si E x x Prog pacing clock Externally triggered a 4 inputs 1 output s 4 12 bit DACs a 4 16 bit counters Technol
119. e the last knob setting will change from Reverb Delay to Pitch Offset Two new serial terminal exam ple displays are shown in Figure 3 A pitch offset of 64 results in no pitch shift whatsoever Settings from 65 to 128 result in an increase in pitch and settings from 0 to 63 result in a decrease in pitch There is actually much finer resolu tion available to apply to the pitch shifting algorithm The input range from the knob timer is scaled to pro vide a usable pitch offset range to the algorithm In the algorithm pitch off sets of 0 to 255 result in lower pitch 256 is for no shift and 257 to 65 535 result in higher pitch although it gets ridiculously and uselessly high after a couple thousand counts However www circuitcellar com Exclusive Ethernet Highway Over 50Mbps Dynamic Memory Allocation 16 or 8 bit Data Bus Width Plug in module ARM Based Evaluation Board for Usable without H W design for W5300 W5300 s High Performance Transformer and RJ 45 WIZnet 3rd Party e market place WIZ ii net WWW Wizwiki net WIZnet un Sunat Een www wiznet co kr accessing all of these counts would require redesigning the knob timer to use a full 16 bits as well as reselecting components to create an appropriate charge time to match the timer s new period Or two buttons to step up or down through the available pitch offsets Both solu tions seemed unneces sary for this project which wo
120. ectronics com Free 96 page catalog 1 800 826 5432 SpectraPLUS 5 0 Audio Spectrum Analysis Features Sound Card based I O FFT sizes to 1048576pts 1 96 Octave Up to 24 bit 200kHz sampling rates 3 D Surface and Spectrogram Digital Filtering Signal Generation THD IMD SNR Transfer Functions DDE Macros Data Logging Vibration Analysis Acoustic Tools FREE 30 day trial www spectraplus com Pioneer Hill Software PH S 360 697 3472 voice pioneer telebyte com Phone 719 520 5323 Fax 719 520 1867 Box 60039 Colorado Springs CO 80960 BASIC Compilers for PlCmicro Easy To Use BASIC Commands Windows 9x Me 2K XP Interface PICBASIC Compiler 99 95 BASIC Stamp 1 Compatible Supports most 14 bit Core PICs Built in Serial Comm Commands PICBASIC PRO Compiler 249 95 32 bit signed variables and math operations Supports Microchip PIC10 PIC12 PIC14 PIC16 PIC17 and PIC18 microcontrollers Direct Access to Internal Registers Supports In Line Assembly Language Interrupts in PICBASIC and Assembly Built in USB I2C RS 232 and More Source Level Debugging Boards Available for Most PIC MCUs Serial LCDs 2 line x 16 39 95 4 line x 20 49 95 Quantity Discounts Available Issue 217 August 2008 H Documentation and Schematic Pricing from 8 95 to 19 95 CIRCUIT CELLAR See our full range of products including books accessories and components at www melabs com www circuitcellar com
121. ed on the source code for the Boot ROM which is supplied by Analog Devices Unnec essary features such as support for devices other than the SPI EEPROM were removed while new features were added The new features include support for Atmel DataFlash in either 256 byte Page mode or 264 byte Page mode and the ability to select multi ple loader files based on the pointer stored at offset 26 in the EEPROM Otherwise it performs the same basic OxFFFFF Reserved system OxE0000 Empty space 0x60000 Empty space 0x40000 0x20000 Empty space 0x00000 Figure 3 The right hand side of this diagram shows the overall layout of areas within the EEPROM while the left hand side shows the internal structure of a single LDR file www circuitcellar com CIRCUIT CELLAR PIC SERVO MOTION CONTROL MOTION CONTROLLERS FOR controller chips controller boards JEFFREY KERR LLC THE SERIAL PORT LIVES Everything you need to know about COM ports USB virtual COM ports amp E asynchronous serial ports for embedded systems Hardware amp software for RS 232 amp RS 485 Wireless options and more Serial Port Complete Second Edition Jan Axelson ISBN 978 1 931448 06 2 39 95 Lakeview Research LLC www Lvr com From the author of USB Complete Mrs 64 PROS RAN ACED T Learn CPLDs ja the fun way with the MACH64 This cotriplote kit comes with everything you need to
122. en cause it to point to the next item in the EEPROM following the DXE image Furthermore the loader can option ally mark the code block of the first DXE file as an INIT block This means that both the first and second DXE files in a multi DXE loader file will get loaded and executed in sequence by the Boot ROM SUPPORTING FIELD UPDATES In order to support firmware updates in the field in a robust man ner it is necessary to have the capabil ity of storing more than one copy of the application code in the SPI EERPOM the one currently execut ing and the newer one being installed Until the install process is completed and verified the DSP will execute the older version on any hardware reset Furthermore it is a requirement that the build process for the application is supported by the standard ADI Visu alDSP development environment boot ROM Internal processor for On chip calibration code RAM and control Asynchronous serial port UART sms On chip data RAM Atmel DataFlash boot PROM Analog rate gyros Figure 1 The Blackfin includes both RAM and ROM on chip with the RAM divided into separate areas for code and data The on chip SPI hardware interface can be configured for either master or slave operation and can be used to boot the processor Issue 217 August2008 35 www circuitcellar com CIRCUIT CELLAR Step 1 Boot ROM Code RAM External EEPROM Data RAM INIT Block Step
123. ensors A web cam pointed at the boiler s digital control panel shows the LEDs representing the current state of the thermostats burner and zone pumps It s a simplification but let me just say that being told have a low temperature alert is better understood when can go see that the bedroom thermostat is indeed call ing for heat the zone pump for the bedroom is on and the physical room temperature is 48 F obviously that particular zone pump is bad and need to call the oil maintenance guys to replace it For the most part the quantity and type of sensors l ve connected to my HCS have been predicated on catastrophe avoidance rather than audio video switching or lifestyle enhancement still feel that s the way it should be but today there s a new wrinkle All of the energy monitoring electronics on my new PV system along with the prospect of 5 gallon home heating oil suggests that should be doing more oil monitoring too How long does each zone pump run i e Which zone is sucking all of the heat What is the total oil burner run time i e How much total oil consumption What are the temperature swings in each heating zone i e Heat transfer rates dirty filters The first rule in home brew sensor connection Do No Harm Basically try not to trash your heating system or blow up your house when you accidentally short the connecting wires or the HCS self destructs Recording zone run times requires HCS sensors on the pump con
124. erimenter Kits for the CARD and a docking station Full access to all TMS320F28x digital signal controllers DSCs are now available The controlCARD pins is provided by the docking modular kits enable the rapid prototyping of DSC based communica station along with a four pin RS 232 interface tions infrastructure industrial and consumer applications with inter and a breadboard area adding components changeable processor card modules controlCARDs Experimenter Kits with breadboard areas for full access to device signals and appli Texas Instruments Inc cation specific DC DC and AC DC digital power development kits www ti com To further reduce development time each kit includes code exam ples and full hardware design details along with Texas Instruments s Code Composer Studio CCStudio 32 KB limited IDE By adopting the new TMS320C2000 controlCARDs OEMs can rap idly build prototypes and even full production systems using the com plete controller subsystem that comes on a small 90 mm x 25 mm removable 100 pin DIMM form factor card Key analog digital I O signals and JTAG test pins are available through the controlCARD interface Only a 5 V input is needed because all other power levels are provided on the board The first two controlCARDs are based on the TMS320F28335 floating point DSC running at 150 MHz with 512 KB of flash memory and the F2808 fixed point DSC at 100 MHz and 128 KB of flash memory The F28335 and F2808 controlC
125. ernational postal money order or check drawn on U S bank Direct subscription orders and subscription related questions to Circuit Cellar Subscriptions P O Box 5650 Hanover NH 03755 5650 or call 800 269 6301 Postmaster Send address changes to Circuit Cellar Circulation Dept P O Box 5650 Hanover NH 03755 5650 Circuit Cellar amp makes no warranties and assumes no responsibility or liability of any kind for errors in these programs or schematics or for the consequences of any such errors Furthermore because of possible variation in the quality and condition of materials and workmanship of read er assembled projects Circuit Cellar amp disclaims any responsibility for the safe and proper function of reader assembled projects based upon or from plans descriptions or information published by Circuit Cellar The information provided by Circuit Cellar amp is for educational purposes Circuit Cellar amp makes no claims or warrants that readers have a right to build things based upon these ideas under patent or other relevant intellectual property law in their jurisdiction or that readers have a right to construct or operate any of the devices described herein under the relevant patent or other intellectual property law of the readers jurisdiction The reader assumes any risk of infringement liability for constructing or operating such devices Entire contents copyright 2008 by Circuit Cellar Incorporated All rights reserved Circuit Ce
126. esses or in large industrial companies Most of the top companies are our customers The crucial reason for selecting EAGLE is not usually the low price but rather the high end functionality along with the ease of use And EAGLE users appreciate the outstanding level of support which at CadSoft is always free of charge and is available without restriction to every customer New Version EAGLE 5 0 Schematic Capture Board Layout Autorouter These are the real cost killers Version 5 0 is even easier to use especially for beginners due to an enhanced user interface Version 5 0 Highlights Stand alone schematic editor available Automatic signal contact cross references using frame coordinates Right mouse click for more consistent Windows Ul User definable attributes for parts Schematic sheet management Hiding approved DRC and ERC errors PRINT preview and text searchable PDF output Improved search engine for help And much much more Light Standard Max number of 1 99 999 schematic sheets Max board size 4x3 2 inch 6 4x4 inch 64x64 inch Max of signal layers 2 4 16 Layout or Schematic Editor 249 498 Layout and Schematic Editor 498 Professional Standard and Light Editions have full functionality except for the limitations mentioned in the table You can use EAGLE Light for evaluation and non commercial applications without charge Download it from our web site 996 Layout Editor an
127. essibility cost and advancement You should be able to easily obtain all of the inverter s compo nents if not purchase an assembled system and once con structed it will be able to power a wide range of AC induc tion motors ACIMs Obtaining a typical three phase high power inverter for driving an ACIM can cost between 8 000 and 25 000 In this article we will present a cost effective method of applying an alternative source of ener gy Any technically minded person should be able to com plete this project for around 2 500 Our inverter was constructed with a control board and software based on Microchip Technology s MC 1 develop ment board and three dual IGBT modules with gate driver boards from Powerex We used these development tools to build a basic 100 kW three phase inverter in an open source process which can be continually improved on All of the inverter s components of the inverter design are off the shelf units readily available at several elec tronics distributors The parts are subject to change if the open source design is modified to suit a user s needs or improved by advancing technology This aspect of the inverter s design provides for the non restrictive application of the system It gives you the freedom to choose a motor that was not originally designed for a vehicle For example 22 Issue 217 August 2008 CIRCUIT CELLAR we used an ACIM that was intended to drive an elevator The
128. everb effect in real time To achieve either of these effects you need a buffer to store all of the samples in before it s time for them to be output A special kind of buffer is needed to do this in real time in a streaming fashion Enter the FIFO www circuitcellar com The FIFO buffer is an array of data accessed by two moving pointers the Write pointer and the Read pointer Initially the array is empty and both pointers point to the beginning of the buffer the first byte in the case of 8 bit samples When data is entered into the buffer it occupies the space point ed to by the Write pointer Immedi ately afterwards the Write pointer is incremented to point to the next byte in the buffer Similarly when data is read from the buffer it comes from the location pointed to by the Read buffer which is immediately incre mented to point to the next location When either the Write or the Read pointer reaches the end of the buffer and is incremented it wraps around to the first location The result is a buffer that contains at any given point after it s been filled one complete buffer worth of contiguous audio samples When the buffer is completely full and streaming the Write pointer should be trailing the Read pointer by one sam ple Changing the sample rate or the size of the buffer adjusts how much time is stored With six of the eight RAM pages being used as audio sample buffers setting the rever
129. f audi ble range Because the IGBT modules are capable of high switching speeds and operate at extreme power levels transient voltage and current protection are important An RCD snubber circuit was chosen for its ability to limit peak voltages and reduce total circuit losses including switching and snubber losses Low ESR and low self inductance rated components are the heart of the protective design eliminat ing the parasitic and residual inductances that can occur across the IGBT s switches and across the DC bus The inverter can generate approximately 100 kW so it requires an effective cooling system The initial cooling system chosen was based on a liquid coldplate from D6 Industries that costs 180 The cooling rus MN vww circuitcellar com _ Control input 14 13 removed for simplicity 1180 Q CIRCUIT CELLAR system can be configured as a stand alone unit with its own pump and radiator or as part of the vehicle s heating and cool ing system The packaging of the IGBT modules enables all three to be mounted directly on a single coldplate for simple and effective thermal management The gate driver circuits for the inverter are supported by an aluminum bar see Photo 1 This cooling configuration is mounted to the inverter enclosure for a greater heat dissipation area GATE DRIVERS Gate driver circuits are required to control the IGBTs These circuits provide appropriate firing and off time volt
130. fe due to corrosion so I keep any electronics on the outside I can sense the level of the water from the outside with a magnet floating on the water s surface Sensors measure the water level I use the same sensors to meas ure the position of a magnet that rests Switch Dynamic c Q B oO 9 O c iC c O g D 40 e O atop the pellets The system in Figure 2 is what measures the pellet and water levels The brine tank has a float switch asso ciated with the water refill cycle that prevents the water level from rising too high and overflowing the brine tank This float is mounted inside a 4 diameter pipe inside the tank To measure the water level I use a foam float with a magnet in the brine tank To measure the pellet level I use a piece of 0 5 plastic egg crate with a magnet in the brine tank HALL MONITOR In a previous column on electromag netics I discussed how a magnetic field is produced around a conductor that has a current passing through it Electric Motor Technology Theory Construction And Requirements Circuit Cellar 216 2008 When this conductor is within an external mag netic field the two magnetic fields create a force that tries to move the conductor This force also has an effect discovered by Edwin Hall on the relative position of the current within the conductor see Figure 3 If current flows through a conductor x axis and you measure across the con
131. ffer MSO5022 SALE 799 890 6 in 1 USB scope adapter 200kHz 2 ch 10 bit scope 2 ch spectrum analyzer 2 ch chart recorder 16 ch 8MHz logic analyzer 5 ch signal gen 8 ch pattern gen SPI I2C 1 w UART decoding PoScope with probes 199 RF Testing Economical portable RF test enclosures for initial compliance testing from 1295 Shielding Tents with external frame instant up down for emissions free room from 3500 Serial Ethernet Cable rs Network your serial product easily without a PC using this 28 cable Provides an instant IP address RS 232 port compatible with most 10 100mpbs Ethernet hubs eCOV 110 P SD Storage Tiny module for adding up to 2GB SD data storage to microcontrollers Simple serial data transfer 3 6 6V 25mA Status LEDs uDrive uSD G1 USB to 12C 39 Devasys Provides a simple drop in solution for connecting your PC to 90kHz 12C 20 I O lines Free software Use multiple boards for more I2C lO USB I2C IO 100 200 300MHz 2 ch 2000 wfm s refresh rate FreeCase DS1102C 400MS s DS1102A 2GS s DS1202A 2GS s 1595 DS1302A 2GS s 1995 Low Cost Scope 999 1295 2 ch 40 100 200MS s 8 bit scope range with 5 10 25MHz bandwidth and USB2 0 for fast screen updates Inc scope FFT logging software case probes PS2203 4 5 from 297 Automotive Testing Auto Diagnostics Award winning kits turn yours into vehicle electrics diagnostic tool PS3423 kit 2
132. g stuff the old way just doing it better Notably hardware including FPGAs was still hardware and software was still soft ware and never the twain shall meet One of the first soft core CPUs I recall was KCPSM a skunk works project by Ken Chapman of Xilinx As the name implies his tiny 8 bit unit was barely more than a programmable 78 Issue 217 August 2008 state machine but nevertheless an actual processor in an FPGA Today the legacy of KCPSM lives on now officially blessed by Xilinx as PicoBlaze K Chapman Solar Panel Monitor Circuit Cellar 185 2 005 KCPSM was nifty but it was so tiny and specialized it simply reinforced the impression that a soft core could never compete with a real CPU That premise changed one day in the early 1990s when I found myself in the lair of Silicon Valley FPGA guru Philip Friedin There I saw his home brewed R16 16 bit soft core CPU run ning in a Xilinx FPGA see Photo 1 Beyond the cool blinking LED demo R16 was a real CPU that did real work CIRCUIT CELLAR as a dynamically loaded test processor in one of Friedin s rocket science projects The message in these early soft core designs was profound but also way ahead of its time Through the 1990s FPGAs stolidly stuck to their tradi tional ASIC replacement strategy targeting hardware designers Soft core CPUs remained little more than eccentric curiosities for a cult of true believers Flash fo
133. g to receive the dream husband award when piped in with I don t have any sports obsessions But then from the other side of the fire pit my wife yelled You d have to take time off from all your other compulsions to fit it Amid laughs from the crowd she continued Have you looked at all the black boxes flashing lights and wires around here lately OK Dear You got me Its laughable but true It seems like I m always pulling wires to connect one thing or another In the early days it was RG 6 cable everywhere to distribute cable TV and C band satellite signals Then came speakers security system sensors video cameras etc The real volume wiring started with my forever evolving and expanding home control system HCS iterations and it has never stopped Let s just say that the latest wiring is mostly CAT 5 and I m on my fifth 1 000 reel since started expanding the HCS to include web interactive monitoring about six years ago Call it an obsession if you want to but like the satisfaction of knowing what s going on There is nothing worse than coming home from a trip and finding a foot of water in the house or getting a call from one of those vacation home monitors screaming low temperature alert then what In fact during the last two years my oil heating system has hiccuped twice while was 1 000 miles away Fortunately can diagnose a lot via the web through a combination of video cameras and temperature s
134. gend Unmasked boards ship next day Www apcircuits com VISA MasterCard PayPal CPC mensen Bo I ELECTRONICS INDUSTRIES CIRCUIT CELLAR OEM Products Handheld TXS Feature LOW COST LONG RANGE TRANSCEIVER REMOTE CONTROL TRANSCODERIC Direct sorta imerfoce K Low power comsumption uL PLL aynthesized architecture RSE and power down functions 2 Compact surface mount package No external RF components except anipnna Lang Range Madulas p FCG PRE CERTIFIED amp ready t cusfromire mr your amicam Function Modules Locri 1AE AOLA A closer lock at Linx innovation Up to B inputs Bi dirschanal control a Trenamitter ID output Autamatie confirmation Secure 27 possible adenn a Latched and or momentary outputs 159 Ort Lane Merlin OR 97532 EN TECHNOLOGIES Issue 217 August 2008 29 f ia ton Tana ees er tee rete T L iss laun bala TIERS Dg ifja c tiga dgalibhe a HES mg Pas TEE TEA LEN mm wel iad aH R E 3 L L i J EJ F 1 iagt tiistain tiisi cinli ret pisti L 1 Pe g TED T L 111111111 HII 2 1111111111 3 u H H HH HHRHH HHHH 1 1 ina Iann nants d i C T 1 ium b38 L4 a4 4 Photo 5a This is the LabVIEW HMI that enables you to adjust the motor controller s PID tuning parameters The sliders adjust the PID of the flux torque and speed and save the values in an ar
135. gg crate to rest atop the pellets It indicates the height of the remaining pellets www circuitcellar com The Newest Embedded Technologies New Products from WiFi BLUETOOTH LA N N L IWO i D lt RFID i EM JOIH EMBEDDED CONTROL NETWOR Mas EE E USB A WLAN x GPS B iu ETO oI H fg www mouser com rabbitsemi a ETOOTH ZIGBEE USE om OR 0 D USB MHES i MatchPort b g tere Cc T A i i Md a JN E ems sinl s TR BENE Mm y e E Embedded Device Server SSeS E e m dd p s 5 L L H j E E EU xi www mouser com lantronix a e ERES The ONLY New Catalog Every 90 Days Experience Mouser s time to market advantage with no minimums and same day shipping of the newest products from more than 366 leading suppliers freescale a tti company Flexis DemoQE128 Demo Board The Newest Products www mouser com freescale a P oe For Your Newest Designs Over A Million Products Online Figure 5 This application requires the sim plest of microcontrollers Activated sensor positions are indicated by blinking a code on the LEDs A two digit decimal blink code indi cates the level of the pellet height red LED 5V Regulated from wall transformer From sensors PIC12F510 No other PCB design tool gives you more value per dollar Boards designed under EAGLE are developed in one man busin
136. gh a SPI just like the EEPROM supporting this feature would require only adding code to handle the FAT file system An addi tional benefit to the SD card approach would be that scene data could easily be written or backed up to a PC with out actually being connected to the DMX Portal It is possible to write a software interface that performs these functions using the available commu nication interfaces but it is not as simple as just reading a file from an SD card Matt Ernst mbernst gmail com is a graduate of the University of Wiscon sin Madison School of Engineering He has a strong interest in the automation and control systems used in the enter tainment industries Matt is a staff analog hardware engineer at National Instruments He designs high speed test and measurement hardware PROJECT FILES To download code go to ftp ftp circuit cellar com pub Circuit Cellar 2008 217 RESOURCES FreeStyler http users pandora be freestylerdmx B Suffolk USB DMX Project www usbdmx com protocol html United States Institute for Theatre Technology Inc DMX512 A Specifi cation www usitt org SOURCES MPLAB IDE and PIC18F4620 Micro controller Microchip Technology Inc www microchip com W5100 Ethernet controller and WIZ810MJ evaluation board WlIZnet Inc www wiznet co kr en Make sure you re signed up to receive Circuit Cellar s monthly electronic newsletter News Note
137. gives no hint of the amazing technology at work a 32 bit pipelined soft core running a compiled C program in a 600 000 gate FPGA all held together by gigabytes of chip design and software tools stitched together your design outline CoreConsole hands the project off to Libero and you take it from there Naturally a soft core solution needs software tools Actel offers SoftConsole a serviceable and familiar solution based on GNU tools and an Eclipse based IDE and debugger And there s also plenty of third party sup port from notables like Keil now owned by ARM and IAR Systems Given its Thumb roots the M1 should be an easy add on for any tool provider supporting other ARM cores You can give it all a test drive with an Actel M1 enabled development kit such as the Igloo based setup M1AGL DEV KIT SCS I played with see Photo 4 Note that versions of the kit based on ProASIC and Fusion chips are available as well It seems that I m invariably forced to upgrade my PC every time I install the latest and greatest FPGA toolchain So the first thing I looked for when I opened the kit was System Requirements Sure enough the doc says you need XP Professional and I m running XP non professional or whatever they call it So once again everything came to a screeching halt so I could go through the fire drill of upgrading my PC Not I just installed anyway And for tunately everything seemed to work well enoug
138. gn Superior Performance and Mass Storage for RCM4300 RabbitCore e Web interfaces and graphics e Rabbit 4000 58 98 MHz e Data logging e 10 100Base T Ethernet Security and encryption e Up to 1GB of miniSD e 8channel analog input 12 bit Free Book Get Your Development Kit Today for 259 S gt with kit Development kits include everything to start your development Dynamic C software RCM4300 RabbitCore module 512MB miniSD card development board programming cables and accessories RABBIT 2900 Spafford Street Davis CA 95618 Tel 530 757 8400 www rabbitkits com 08081 Listing 2 The communication interface provides an interrupt endpoint for sending notifications to the USB host Communication interface descriptor 0x09 0x04 0x00 0x00 0x01 0x02 0x02 0x02 0x00 Class Subclass Protocol Descriptor size in Dytes INTERFACE descriptor type Interface number Alternate setting number Number of endpoints CDC communication abstract control V 25ter AT commands Interface string index model Listing 3 The data interface provides two endpoints for sending and receiving COM port data Data interface descriptor 0x09 0x04 0x01 0x00 0x02 0x0a 0x00 0x00 0x00 Class Products MAX232 or similar RS 232 converter Microcontrollers generally don t have dedicated port bits for RS 232 s status and control signals but a device can use any spar
139. gy USB connectivity sample zone a special program created for readers of Circuit Cellar magazine 5 L L L L F L USB PIC Microcontrollers Thousands of qualifying Circuit Cellar readers can receive 8 16 and 32 bit MCUs with USB connectivity providing easy migration with a single development environment A select Request these samples and discover other group will also receive complete USB special offers from Microchip Visit Starter kits to better evaluate their WWW circuitcellar com USB design options CIRCUIT CELLAR MICROCHIP Visit Microchip s USB Design Center for all current application notes software downloads development tool support and complete product information www microchip com usb FEATURE ARTICLE by David Tweed A Bootloader For Blackfin David designed a two stage bootloader that allows application firmware to be updated in the field to support bug fixes and additional features for specific end user applications It also adds capabilities to the native boot processing of the Blackfin chip Although some details are specific to the Blackfin family of DSPs some general features may be helpful on other CPUs Na long ago I was working on an inertial measurement unit IMU that was based on the highly integrated ADIS16350 inertial sensor from Ana log Devices that Tom Cantrell wrote about in his column in Issue 208 Thanks for the MEMS 2007 This is a six axis M
140. h to at least get through the basic demos see Photo 5 But I suppose there are no guarantees if you don t have XP Pro Oh yeah the doc also says so sorry when it comes to Vista 86 Issue 217 August 2008 Bottom line buyer beware or at least be aware when it comes to FPGA tool chains and PC system requirements Actel has done a lot arguably as much as possible to make the out of box experience fast and easy You still have to move a lot of bits some 32 billion of them by my count i e a 4 GB install and jump through some licensing hoops Nevertheless it wasn t long before I had the M1 up and running in the Igloo chip which was pretty remarkable considering how much was going on under the hood The getting started guide reassures that It is not necessary to synthesize place and route or generate a pro gramming file to get the demo work ing Not necessary and not advisable if you don t know what you re doing I dabbled a bit with the design in Libero but it was quickly apparent that I was in way over my head THE KNOWLEDGE If you want to be a cab driver in London you first must first earn The Knowledge Students study for many months to memorize the thousands of little streets in London and learn the best routes from place to place And they go out every day on scooters to scout around and validate their book learning Similarly if you want to be a great FPGA optimized core designer yo
141. he values 80 25 in the first two bytes indicate a requested bit rate of 2580h or 9 600 bps The value 08 in the final bytes is the number of data bits per transmitted word on the serial port After receiving the parameters the device implements any requested changes The IN transaction of the transfer is the status stage The device indicates success by returning a ZLP no data Request 21h is GET_LINE CODING The device sends its current parameters in the IN transaction The OUT trans action is the status stage where the host indicates success by sending a ZLP In the SET CONTROL LINE STATE request 22h the host tells the device how to set the RS 232 control signals RTS and DTR The host sends the control line states in the third byte of the setup transaction Bit O is the state of DTR and bit 1 is the state of RTS Device firmware detects the request accepts the data and imple ments any changes to the bits The IN transaction is the status stage The device indicates success by returning a ZLP The SEND_BREAK request 23h requests the device to send an RS 232 break signal a positive RS 232 voltage on the TX line for a specified num ber of milliseconds If the requested value is FFFFh the device should main tain the break signal until 7 bytes 80 25 00 00 00 00 O8 8 bytes 41 21 DD 00 00 DD OF 00 7 bytes BD 25 00 00 00 00 O8 CIRCUIT CELLAR USBNVID 0925 amp PID 9060 receiving another SEND
142. he latter Finally the bottom line shows what happens in the same condition with just a small change in the tuning word value 5 167 vs 5 166 The spectrum of spurs is different www circuitcellar com CIRCUIT CELLAR Issue 217 August 2008 67 generated by the PIC and filtered by the MCP6002 all without having to switch on the soldering iron With the advanced simulation option Proteus VSM can even calculate the spectrum of the filtered signal as shown Close to expectations isn t it SILICON SOLUTIONS Even if software based DDS is possi ble there are plenty of impressive sili con versions particularly from Analog Devices An example is an easy to use chip such as the AD9833 a 4 qty 1 000 low power chip fitted in a 10 pin 3 mm x 3 mm MSOP package that enables you to generate frequencies up to nearly 12 5 MHz with 0 1 Hz resolu tion The chip is driven by a standard SPI port which enables you to connect it to any microcontroller Since energy consumption is such an important consideration note that this chip eats RAM SWP OVR Serial I O port Digital ramp generator PROFILE lt 2 0 gt l O UPDATE P ARALLEL TxENABLE PDCLK range up to 65 to 70 dBc and still around 55 dBc at 400 MHz But that was for the DDS core alone and this chip has plenty of other blocks First it has an auxiliary DAC to define the full range amplitude without compromising the quantization noise It can also
143. he pitch offset It was no problem to integrate the pitch shifting algorithm into the mixer reverb project To keep the intercom output pin PO 2 open and because the two could feasibly coexist the serial TX module shares its output pin with a mode button To accomplish this dual purposing an external pull up resistor is required This allows the TX module to output with an open drain low drive instead of a strong drive which does not affect an active low button attached to the same line Basically whenever the serial 46 Issue 217 August 2008 interface is not transmitting the line is a standard High Z digital input looking for a button press When the serial interface needs to transmit it connects the pin to the TX module and sets the Drive mode to Open Drain Low It always waits for the but ton to be released before transmitting to avoid conflicts The button presses will rarely if ever look like valid data to the serial terminal so no erroneous characters appear When the button is pressed the PSoC cycles through its modes Reverb Pitch Shifting and Intercom The latter was added because well it was possible This mode disconnects the Rd signal from the mix so it can be accessed separately on PO 2 implementing a manual form of dynamic reconfiguration by altering the appropriate registers CIRCUIT CELLAR Reverb and Pitch Shifting modes each display a new title line on the serial ter minal becaus
144. her than a DataFlash and the Boot ROM then assumes that the device has 256 bytes per page As a result the Boot ROM will work correctly only if the AT45DBO081D is permanently set to its 256 byte Page mode In order to fully support the 264 byte Page mode a second stage boot kernel is required This works as long as all of the block headers for the INIT block and the boot kernel itself fit into the first 256 bytes of the DataFlash device As long as the boot 36 Issue 217 August 2008 kernel comprises a single code block it can be arbitrarily long well up to 65 534 bytes and extend beyond the first DataFlash page TWO STAGE BOOT PROCESS Therefore we needed to implement a two stage boot process This consists of the boot ROM executing which loads and then executes a second stage boot kernel The boot kernel in turn loads and executes the actual applica tion firmware In order to support multiple copies of the application firmware in EEP ROM at the same time it is necessary to have some storage reserved in the EEPROM to indicate which copy is the active copy of the firmware at any given point in time Within the context of the standard software devel opment toolchain the only way to accomplish this is to include an INIT block The INIT block contains just a return instruction along with four additional bytes of space that get ini tialized to all zeros When the boot kernel gets control it examines those 4
145. hile allowing most of the chip to sleep Of course there s no free lunch and in return for the power savings Igloo sacrifices some speed compared to its Decode Control ProASIC and Fusion cousins Yes FPGA price perform ance and now power have been headed in the right direc tion but that s not to say there isn t room for improve ment Particularly as it applies to soft core processors remember that no program mer ever met a megahertz or megabyte they didn t love at least until a new gigahertz or gigabyte caught their fancy Relying on the silicon wiz ards to make things better is a time honored approach But what goes on the silicon also has an impact and unlike fab technology is something mere mortal designers can influence right now with their choices THUMBS UP Enter the ARM Cortex M1 core designed to squeeze the most out of the FPGA silicon see Figure 1 Like other FPGA soft cores e g NIOS and MicroBlaze the Cortex M1 is free CUWIN4300K K Y CUWIN3500 7 10 2 wide color Touch panel CIRCUIT CELLAR 97 ai DNL E IO Bac Bami ox cana AAOS DI dee Beast e cape Issue 217 August 2008 79 CONFERENCE EXPO Hynes Convention Center Boston MA The 3 3 was created specifically to meet the information needs of the system architects and design engineers who create these complex systems The technical program at ESC is the Fall s largest i
146. his protocol The second protocol is a compact binary code based on a protocol devel oped by the open source USB DMX proj ect Refer to the Resources section of this article This protocol reduces over head to a minimum and has all of the commands required to control the DMX output It is useful if you have config ured the non DMX parameters of the device using the ASCII protocol and want to make changes to the DMX output as quickly as possible A com mand can be sent that will switch between the two protocols while the device is running to allow flexibility between available commands and communication efficiency Another CIRCUIT CELLAR advantage is that the USB DMxX protocol allows the DMxX Portal to be controlled by software that supports the USB DMX protocol I ll cover one such application named FreeStyler in the next section SOFTWARE INTERFACES Because the DMX Portal has many combinations of communication interfaces and protocols there is no ready made application that can easily interface with it in all of the possi ble modes I used the Lab VIEW graphical program ming language to build custom interfaces that could control the DMX Portal via the RS 232 or Ethernet connections using the ASCII or fast binary protocols see Photos 2 and 3 Programming with LabVIEW was helpful because it has libraries for communicating via a serial port or TCP IP It also has many examples that can be easily modified
147. holds the successive points of the output signal It is then converted to an analog signal and filtered CIRCUIT CELLAR www circuitcellar com Phase i Phase to i i Phase Low pass increment l amplitude register filter W converter FCLOCK Figure 2 The basic architecture of a DDS is a variant of the counter based digital generator but it allows a fine frequency resolution thanks to a phase register and a binary adder The key point is that the increment is not necessarily a divider of the phase register maximum value frequency will be doubled As you programmable divider because the with a resolution of the following know you need a little more than phase register doesn t loop back to the two samples per period to be able to same value after each generated peri eo adis 0 0046 Hz reconstruct a sine signal so the max od The table in Figure 3 may help you imum value of W is 2N 1 The understand it What make a DDS a Not bad In fact the maximum fre formula giving the output frequency fantastic building block are the quency will be a little lower due to based on the phase increment is numeric examples Just take a stan constraints on the low pass filter as then dard low performance DDS with a you will see later phase register of N 32 bits and a Four W x Faroe reference clock F 4 20 MHz DDS FLEXIBILITY a Your DDS can then generate any fre Another great advantage of a DDS Don t be confu
148. hone preamp gains and three master gains two selectable adjustable DSP effects four set potentiometer position memory an intercom and voice menus That s quite a mouthful May this series provide a valuable CIRCUIT CELLAR starting point for your next or first PSoC project a Author s note Many of the applica tion notes referenced in this article were recently submitted so they may or may not be available on Cypress s web site at this time For your conven ience the original unedited versions of the relevant application notes are available on my web site along with their project and related files Go to www chrispaiano com for more infor mation In addition I have a few home made PSoC based electronics kits and devices for sale on my site The project described in this article is available as a kit or an assembled unit Chris Paiano has written more than 30 application notes for the Cypress PSoC chipset over the years includ ing such novelties as PongSoC and the Video RTA You may contact him at chris paiano gmail com PROJECT FILES To download code go to ftp ftp circuit cellar com pub Circuit Cellar 2008 217 REFERENCES 1 D Van Ess AN2276 Algorithm Binary Weighted Single Pole IIR Low Pass Filters Cypress Semi conductor Corp 001 32902 2005 2 B Stewart Z8 Encore Based Audio Processor Circuit Cellar 174 2005 3 C Paiano AN13945 Playing WAV Files
149. ic geleclive deplay of unrbubed tracks lime saving new re reiting Teabure mmimum clearance for any combination of net classes add elements 1p group of subtract elements from group CANUSE Features f Pri Acted lt m nmp j PC MAC E Linii aupeurt E Both 11 A 28 bit B aupeart Sere GAH liur Hiii T reda do d Firmware usu rada vis US vs Sample preejrarm in C Cs VEI Dalai Cr ParaBuriie HE Bo med tor mrima pasar cris up t TMbE CAR Add a color touch interiace to your embedded product x High level AS232 Low cost Interface x In stock s Easy to program And color graphics to any WTE hit embedded system Easy tasi and flexible Up and runming in hiara RZACI www reachtech com 510 770 1417 Bi Bopgs reng Fremen DA Basan Z ED www circuitcellar com tincan TOOLS Linux in a 40 pin DIP 200 Mhz ARMS CPU Board 0 1 centers easy to prototype use your existing prototype tools full Linux with 2 6 kernel CD Includes source and schematic HAMMER R KEH TT hii un ere TOU remm Perfect for robotics web servers remote monitoring amp communications www TiNCANTOOLS COm MCS gt Sn celten L ose NE zd l C SMBus ess Bus Monitors S Protocol amp Analyzers L Host Adapters e Mulbpiexers Battery Applications e Software Tonis Micro Computer Control PU ii a hdr of Phils Corea NW T ELM com
150. if it has been set If any value other than 32 is found the second variable water gets the counter value other wise Salt gets the counter value This gives salt the first counter value when the first low is found lower level and water the last counter value when the second low is found upper level If a float mag net is seen by two adjacent sensors the lowest sensor is used for the vari able salt and the highest is used for Initialize Red green LED ON Pause 3s Red green LED OFF FSR TableStart Toggle load Offset BytesToGet Get all SPI bytes Salt water temp Wait 3 s then blink red LED once for each salt ten s digit Wait 3 s then blink red LED once for each salt unit s digit Wait 3 s then blink green LED once for each water ten s digit Wait 3 s then blink green LED once for each water unit s digit Return the variable water The counts in salt are displayed by the red LED The LED blinks once per second for each ten s digit and then again for each unit s digit A digit of zero leaves the LED on for a longer period of time The green LED then repeats the display of level count for the water variable see Figure 6 The LEDs are mounted under the roof over hang outside of the locked well house so they can be viewed by looking out of my living room window Now I can keep track of the system without hav ing to go below ground SIMPLIFYING THE SIMPLISTIC The basic premise of the project is
151. igh speed 14 bit DAC enabling a spurious free dynamic AD9910 8 AUX DAC FSC 4 gt DAC 8 Bit 0 DAC RSET E A 14 Bit b Inverse OX Sync filter Amplitude A Acos wt 8 Data Phase 8 route and Frequency w partition control Asin wt 8 REFCLK OUT S 1 Q YSCLK py dm E O Multichip synchronization E mode Internal clock timing and control Cloc XTAL_SEL Power down control SYNC SMP ERR SYNC IN PLL LOCK PLL LOOP FILTER SYNC CLK SYNC OUT Q EXT PWR DWN MASTER RESET Figure 9 This is the internal architecture of the AD9910 high end DDS chip courtesy of Analog Devices As you see the DDS core is just a small part of the chip It is sur rounded by a zillion advanced high speed digital modulation and control blocks as well as a 14 bit Gsps DAC and a reference clock PLL multiplier 68 Issue 217 August 2008 CIRCUIT CELLAR www circuitcellar com modulated waveforms What else Oh yes it can be synchro nized with other chips if its features are not enough for your application It is managed through a SPI but it also has a high speed parallel bus for time critical applications OK it is not a low power chip 800 mW 1 8 V and 3 3 V and you will have to solder its 100 pins and read its 64 page datasheet if you decide to use it but that s the price you pay for such a list of features Another interesting chip is the Ana log Devices AD99
152. iltering or custom network applications All kits include platform hardware ANSI C C compiler TCP IP stack web server e mail protocols RTOS flash file system Eclipse IDE debugger cables and power supply etBurner Networking in One Day Information and Sales sales netburner com Web www netburner com Telephone 1 800 695 6828 freescale Alliance Member hinking about your next _ Compare the specs TDS2012B MSO6012A 3206 502 2 nemen pee ve m sov mw Analog Channel bit resolution 12 10 12 or 14 Can do hardware trigger referenced averaging Yes bit Yes 10 bit cc cc E REN B 14 bit EM 3 5V gt Analog Input Offset eg Eg oe a lone EB then x then 50V then 100V 80V Bernal moger samt MT EET UE ETT RE EE No Ye 4000k or 2000k Bi 500k 512K 128k 8000k bras m m m m L mutta p d 15 6 mV 15 6 156 mv 0 018 mV X F oS H 60 dB or 72 cara Un oN aC RUIT e act se ime im Width at max sample rate 2 5us width 1 ms width 5 ms width 320 us width 640us width re 20 or 40 ms Peak Captured to eliminate aliasing Trigger delay EL E GES Protocol Analysis a Mot ves Now eee Period Trigger es a the review continues on our website at H 100 MHz Bandwidth e et Slt Dual mixed sig trigger i r TRA Lemi 2 analog 8 digital inputs and ext trig 10 12 or 14 bit sampling 4 or 8 MS
153. includes library source for standard libraries and sample code for I O drivers Also included are a macro assembler linker and a preprocessor The compiler runs on multi ple platforms including Win dows including 64 bit Vista Linux and Mac OS X The C Pro compiler costs 1 495 HI TECH Software www htsoft com www circuitcellar com CIRCUIT CELLAR JTAG une ARM 9 Cortex M3 a USB to JTAG a Fast 720kb s Download Speed a Serial Wire Debug SWD Support s Multicore Debugging Support a Auto JTAG 5 Recognition The J Link can be coupled with a number of available software modules to fit your application needs J Flash is a stand alone application used with the J Link to program internal and external flash devices J Link RDI permits the use of the Link with an RDI compliant debugger J Link GDB Server is a remote server for GDB J Link Flash Download is a module used to download your program inte flash even if your debugger does not have a flash loader J Link Flash Breakpoint permits you to set an unlimited number of software breakpoints while debugging in fash J Link SDK is a standard DLL that extends the full Functionality of the Link to your proprietary application We also offer a JTAG isolator which can be used to ITA ladi offer electrical isolation between your target hardware and the J Link This i5 essential when the develapment tools are not con
154. ing of such a function Initially I was shooting for eight storage sets At 16 bytes a piece this would require only the last two blocks 64 bytes each of flash memo ry to save However as I recorded the words Writing Set and the num bers 1 through 8 I realized I might be pushing the flash memory requirements Sure enough even after all of these new sounds were time compressed and converted to 8 bit 7 8 kHz for mat the PSoC was still about 10 KB short I needed to save some space I quickened Reverb as much as possi ble without losing the pronunciation I shortened Pitch Shift to Pitch and Intercom to Com I removed the word Set because it was unnec essary I still did not have enough space I was going to shorten Writ ing to Save but it would not have made much of a difference At that point I opted to drop down to four stored sets Now everything fits with room left over for the code necessary to implement it I created a constant array contain ing some default sets set 1 has all unity gains with full reverb max pitch shift set 2 has slightly higher gains with lower reverb pitch and so 50 Issue217 August 2008 on to avoid undefined situations I then ensured the compiler placed it in the last block of flash memory Next I wrote the logic necessary to store new settings in this location when the Mode button is pressed while the Scan
155. it there s no reflection regardless of distance Despite those problems a reflected light sensor can provide reliable dis tance measurement in a well con trolled environment For example a sensor calibrated for a specific object with a constant reflectivi ty used with known ambient lighting can work quite well My fingers have a reasonably sta ble reflectivity and aren t at all mir ror like but ambient illumination can vary from near darkness to full sunlight with incandescent LED and fluorescent lighting thrown in for good measure Obviously depending on ideal behavior won t suffice so let s see what will MEASURING REFLECTIONS It turns out that semiconduc tor junctions are inherently www circuitcellar com Raw Voltage Vtople 437 on photosensitive early glass cased diodes caused baffling problems on analog circuits exposed to fluorescent lights Optimizing that effect pro duces a photodiode the basic optical sensor with a reverse current linearly related to the light energy incident on its PN junction The Vishay Semicon ductors BPV23NF infrared pho todiode along the bottom of Photo 2 has an IR transparent black epoxy case that blocks visible light with a molded lens for a 120 field of view Although you can drive an ammeter directly from a reverse biased photodiode and a battery most circuits require a voltage proportional to the current A circuit converting an input cur rent to
156. lar com pub Circuit_Cellar 2008 217 REFERENCES E 1 Powerex Inc CM400DU 12F ModuleTrench Gate Design Dual IGBTMOD www pwrx com pwrx docs cm400du 12f pdf 2 R Severns Design of Snubbers for Power Circuits Cornell Dubilier Electronics Inc 2007 www cde com tech design pdf 3 Powerex Inc BG2B Universal Gate Driver Prototype Board 2005 www pwrx com pwrx app bg2b_application _note pdf 4 Powerex Inc VLA106 15242 Isolated DC DC Con verter 2007 www pwrx com pwrx docs vlal06 15242 pdf 5 Powerex Inc VLA503 Hybrid IC IGBT Gate Driver 2007 www pwrx com pwrx docs vla503 pdf 6 Microchip Technology Inc dsPICDEM MC1 Motor Control Development Board User s Guide DS70098A 2003 wwl microchip com downloads en DeviceDoc 70098A pdf www circuitcellar com I 7 S Bowling How to Turn an AC Induction Motor Into a DC Motor A Matter of Perspective Microchip Tech nology Inc www newarkinone thinkhost com brands promos leading edge Microchip O6 llman pdf 8 R Parekh AN955 VF Control of 3 Phase Induction Motor Using Space Vector Modulation Microchip Technology Inc DS009554A 2005 ww1 microchip com downloads en AppNotes 00955a pdf 9 D Ross J Theys and S Bowling AN908 Using the dsPIC30F for Vector Control of an ACIM Microchip Technology Inc 2004 ww1 microchip com downloads en AppNotes ACIM 20Vector 20Control 2000908a
157. le bandwidth control Multi Channel Logic Analyzer Eight logic trigger channels with event capture E MI BS100U Mixed Signal Storage Scope amp Analyzer Innovations in modern electronics engineering are leading the new wave of DSP Waveform Generator Inc a inventions that promise clean and energy efficient technologies that will Optional flash programmable DSP based function i generator Operates concurrently with waveform change the way we live and logic capture Mixed Signal Data Recorder Record to disk anything BitScope can capture Supports on screen waveform replay and export It s a sophisticated world mixing digital logic complex analog signals and high speed events To make sense of it all you need to see exactly what s going on in real time BS100U combines analog and digital capture and analysis in one cost User Programmable Tools and Drivers effective test and measurement package to give you the tools you need to Use supplied drivers and interfaces to build navigate this exciting new frontier custom test and measurement and data acquisition solutions l s T l 5 Standard 1M 20pF BNC inputs Smart POD Connector Opto isolated USB 2 0 12VDC with low power modes BitScope DSO Software for Windows and Linux BS100U includes BitScope DSO the fast and intuitive multichannel test and measurement software for your PC or notebook Capture deep buffer one shots display waveforms
158. les significantly better performance than standard 5 mm emitters The combination of a wide view ing angle high power output up to 1 A and high speed makes the TSFF5510 infrared emitter ideal for infrared audio and video data transmission in free air data transmission applications with high modulation frequencies or high data transmission rates With the industry s lowest forward voltage of 1 45 V at 100 mA and 2 15 V at 1 A the TSFF5510 emitter provides the basis for uniform operation per formance especially in a series circuit layout The device features switching times of 15 ns meeting the requirements for high modulation operation of 23 MHz and supporting data transmission rates of up to 16 Mbps Suitable for high pulse current operation the TSFF5510 offers a peak wave length of 870 nm 55 mW optical power at 100 mA and radiant intensity of 32 mW sr at 100 mA The device offers a compact leaded package with a lens radius of 2 35 mm a lens height of 3 8 mm a lens width of 4 8 mm an epoxy bottom plane diameter of 5 9 mm and a lead distance of 2 54 mm U S delivery in 100 piece quan tities costs 0 45 Vishay Intertechnology Inc www vishay com EVENT DATA RECORDER WITH INTEGRATED F RAM MEMORY The FM6124 is the industry s first F RAM based event data recorder EDR The FM6124 is an integrated event monitoring solution that continuously mon itors state changes stores them in the F RAM and alerts the system to the
159. llar is a registered trademark of Circuit Cellar Inc Reproduction of this publication in whole or in part without written consent from Circuit Cellar Inc is prohibited www circuitcellar com USB Connectivity for Embedded Designs T i i ls E la P a K i E E z l R l lt s 3d i 19 O1JUOD jeubls jeubiq Li ka LJ bF te J d wo d d d i D A a m i h 1 PIC Microcontrollers IA TAIEX If you need Full Speed USB 2 0 device embedded host dual role and USB Starter Kits accelerate development On The Go solutions Microchip Technology has them available today of USB designs using 8 16 or 32 bit MCUs We offer 8 16 and 32 bit MCUs with USB connectivity providing easy starting at only 59 98 migration with a single development environment This maximizes pin compatibility and seamless code migration from 20 to 100 pins enabling you to scale your USB design with ease Download FREE USB software including source code e Host Stack e Thumb Drive Support Mass Storage e OTG Stack Driver SCSI Interface 16 bit and 32 bit e Device Stack File Management Application Software e Class Drivers HID Mass Storage and CDC Drivers The Microchip name and logo the Microchip logo and PIC are registered trademarks of Microchip Technology Incorporated in the USA and in other countries 2008 Microchip Technology Incorporated All rights reserved
160. llator There is no reason why I can t run the PIC18F4620 faster with an external oscillator Doing so would help improve the performance of some tasks such as command processing Having a faster clock to reduce the processing time would help make the system run much smoother without www circuitcellar com costing too much One improvement that could be made to the Ethernet interface would be to change from the UDP protocol to the TCP protocol UDP has no mechanisms to guarantee packets are not lost It also has a maximum pay load size that can be a problem with some of my commands that generate large amounts of response data A TCP based link would automatically try to resend dropped packets reorder packets that are received out of sequence and detect a communications failure TCP also behaves as a constant datastream so it would not be subject to a maximum payload length like UDP The W5100 supports TCP Thus it would not be difficult to make this transition I think it would greatly improve the quality of the communi cation interface on the DMX Portal I also want to improve the data stor age space for user defined scenes For simplicity I chose to use a serial EEP ROM for my storage but it offers only limited space An SD card would have been a much better choice because it offers a low cost storage solution that easily holds an entire show s worth of scene data Because SD cards can be accessed throu
161. lopment time of future assembly based projects and help bridge the readability gap between assembly and C Multitasking in this project is com pletely interrupt driven When the device first powers up all hardware peripherals and software variables are initialized before interrupts are enabled The RS 232 and Ethernet interfaces have dedicated interrupts that call a process to collect the received data into a circular buffer within the PIC data memory Once a complete command is detected inside the circular buffer a blocking com mand processor routine is called that validates the command and executes the appropriate action Because this command processor routine is block ing it is important that the com mands are executed efficiently so they do not interfere with receiving the www circuitcellar com Figure 4 The DMX expansion board contains a standard DMX connec tor a CMOS to RS 485 converter IC and eight push button switches to debug the digital scene trigger functionality Note2 L m NOTE 1 Populate R1 for DMX output Populate R2 for DMX input next command or refreshing the DMX output Writing in assem bly was particu larly helpful here because it was straightforward to analyze how many CPU cycles were required for each command to exe cute and optimize them as much as possible Hardware timer interrupts are used to trigger the execution of the DMX refresh routines and provide ti
162. mentation While it shares the shorter op code philosophy of an 8 16 bit MCU the Cortex M1 is still a real 32 bit computer inside see Figure 2 One key Cortex advantage carried forward is a Harvard architecture with simultane ous instruction and data access a step up from the combined instruction data bus of ARM7 The Cortex M1 exploits this dual bus advantage with separate instruction and data Tightly Coupled Memories ITCM and DTCM for high speed access kind of program mer directed caches There s also the familiar nested vectored interrupt con troller NVIC to accelerate real time interrupt driven applications APPLE VERSUS ORANGE The M1 soft core also comes with a complete hardware debug engine that has all of the fancy features designers have come to expect including break points watchpoints single step regis ter memory access and so on This is an opportune moment to Figure 2 The Cortex M1 has the code density and silicon footprint of an 8 16 bit core but there s a 32 bit engine ALU register file address space under the hood Issue 217 August 2008 83 C PROBE A PRETTIER PRINTF These days every processor comes with a full suite of fancy tools courtesy of commercial e g ILAR Systems and Keil and open source e g GNU and Eclipse suppliers The multi windowed GUI IDEs have every imaginable feature and then some But sometimes as I grapple with their dizzying array of windows and menus
163. ming gt NOTE 2 Populate for DMX receive only KEIL An ARM Company cues for the automatic fade engine The DMX output refresh was designed to be a blocking process like the command processor This simpli fies dealing with commands that change the contents of the DMX frame buffer The DMX frame buffer is a 512 byte section of the PIC18F4620 data memory that stores the current 8 bit values for each of the 512 DMX channels Because the DMX protocol allows for delays between each data slot it would have been possible to write the code so the DMX refresh was not blocking This would have improved the system s ability to deal with large amounts of incoming command data during refreshes But it would also have required care in dealing with updating the frame buffer in the middle of a refresh Another reason the refresh was made to be a blocking process was that it effectively gave the highest pri ority to the DMX output If one of the command interfaces was flooded with incoming data it could have been Software Development Tools The Leader in Microcontroller Development Solutions C C Development Kit including best in class compilers genuine Keil u Vision and royalty free RTX RTOS system USB and CAN support Call 1 800 348 8051 for a free demo CD CIRCUIT CELLAR Keil RTOS and Middleware components are specifically optimized for embedded systems and include TCP IP Fl
164. mp FE cat le 1 Robot Kits Line followers Robot arms exapods Chassis p iec sha TNT a C ompo rens OA e Doxes se Wheels ball Motion Control F Servo controllers Motor controllers red user LED on PD1 ATmega4a 168 microcontroler programming connector 20 MHz clock ET k Solder Paste Stencils Use our low cost From 25 solder paste stencils to quickly assemble B illl E 22 your surface mount designs T amp amp REN EE BE SE BE a B ET NB mu wu Custom Laser Cutting From 25 a 4 E ates m s wmm Issue 217 August 2008 13 FEATURE ARTICLE by Matt Ernst Ww IZnet DESIGN CONTEST THIRD PLACE CONTEST WINNER T DMX Portal is a self contained lighting control unit that you can use to control moving lights or special effects equipped with a DMX interface see Photo 1 The project provides a low cost flexible way to interface embedded systems with DMX devices and to allow DMX control to be distrib uted over long distances using Ethernet Most programmable lighting is designed for stage performances Stand alone lighting boards are the most com mon playback controllers programming interfaces used in these applications The programming interface provided by the lighting boards is implemented via slider controls and buttons similar to an audio mixer This type of interface is most appropriate for stage performances Photo
165. n of Photo 2 with call outs is posted on the Circuit Cellar FTP site We did this for code compatibility and to reduce actual development time Several simple changes were made to the PCB design The bias resistors on the gate drivers were moved to the output of the logic buffer and given the capacity to func tion as pull up pull down or float depending on the place ment of a jumper Regulators were added to the board pro viding stable 5 and 15 V sources Additional decoupling capacitors were placed in the circuit to reduce the inevitable noise motor noise and switching noise that is inherent to the system The complete control board is shown in Figure 3 We revised the control board four times The first board was tight with limited room for additional prototyped cir cuitry This would be excellent for a production model but a nuisance for development Further revisions increased the board s size and spaced out the components There is now more real estate for a larger prototype area allowing for cir cuit changes if required The final board includes all of the changes The schematic is available on the Circuit Cellar FTP site Tibbo TECHNOLOGY LAS UN A m a Keypad Beeper 49 0 Lines 4 Serial Ports Includes cross debugger that does not require any special hardware ICE machine With optional WA1000 Wi Fi module Requires additional hardware 24 Issue 217 August 2008 CIRCUIT CELLAR www
166. nalyzer va SPI Bus Analyzer SPI protocol exerciser and analyzer for standard SPI and non standard 4 wire and 3 wire serial protocol interfaces up to 50 Mbps PC control via free GUI 8PI Control Panel Software SPI Xpress Serial Server 699 RS232 422 485 device server for network enabling legacy serial devices 1 2 4 8 16 32 ports 10 100Mbps 230kbps Static IP DHCP PPPoE Portbase 3010 RS232 from 149 USB Loggers EL USB 1 Standalone USB temp data logger 25 C to 80 C 49 EL USB 2 humidity 79 EL USB 3 voltage 69 EL USB 4 current loop 69 EL USB CO Carbon Monoxide 89 1 2 4 8 16 x RS232 Add COMports via your PC s USB Port USB COM S 20 USB 2COM USB 4COM USB 8COM USB 16COM RM rackmount 459 OTTCMEUPPORT EMC Spectrum Analyzer J Handheld Palm PC based 2 7GHz Spectrum Analyzer Multiple sweep settings store wfms set ups etc Use WiFi PC for email reports calculations PSA2701T 60 100 120MHz AWG 60 100 120MHz USB 14 bit ARB w USB RS 232 LAN GPIB 10 built in wfms 6 digit 200MHz frequency counter opt 16 ch gen DG3061A 1895 DG3101A DG3121A 2795 3995 Pen Scope PS2105 25MHz USB powered Scope in a probe Up to 100MS s 24kS buffer C VB Delphi LabView VEE drivers PS2105 25MHz 100MS s 369 PS2104 10MHz 50MS s 234 GPS Logger TrackStick Il Pocket sized logger tracks position data for vehicles personnel etc Records date time location
167. nd protocol and will be automatically saved to the EEPROM each time they are changed COMMAND INTERFACES The DMX Portal provides Ethernet and RS 232 interfaces so it can be connected to a variety of systems The Ethernet interface is useful if the sys tem into which you want to integrate DMX functionality has Ethernet con nectivity or if it will be located a long distance away from the DMX portal The RS 232 interface is useful for connecting to embedded systems 18 Issue 217 August 2008 Command Send command Command Success Channel J Set DMX Chan Ji New Level E go Photo 2 Using LabVIEW it is easy to create utilities that communicate over standard PC I O ports and have professional looking graphical user interfaces This utility allows the DMX Portal to be accessed through the RS 232 interface using the binary protocol because they frequently have serial output capabilities Plus the RS 232 interface offers a reliable low cost connectivity option with little soft ware overhead Each of the command interfaces supports two different command pro tocols The first protocol is ASCII text based and provides a large set of easily readable commands to control every aspect of the DMX portal This protocol is most useful if you want to control the DMX Portal through a standard terminal program Because the commands are text based more processing overhead is required to transmit and process commands using t
168. ndustry conference offering in depth and unbiased content that delivers real world solutions from leading technology experts Commercial amp Open Source Operating e Multi core Processors amp Programming oystems s Real time Development Debugging Verification amp Test e Security e Design Team Management Software Development s DSP amp Multimedia Algorithms amp e Virtualization Implementation e Wired amp Wireless Networking s Hardware Design including Programmable Logic EARLY BIRD REGISTRATION NOW OPEN www cmp egevents com web escb registration signature Sponsor Platinum Sponsor KY Windows Embedded vechindighas EVENTS Exclusively at Jameco The Lowest Prices Guaranteed Save 3 to 5 Looking to save on thousands of Name Brand components Jameco offers their popular products for 3 to 5 below market price and we guarantee it 3 Levels of Choice 3 Levels of Savings Save 15 25 Save more when a specific manufacturer is not required Major Brand semi s are sourced from 5 6 major manufacturers plus we offer Jameco brand and generic passives for even greater savings Other Jameco Advantages M We offer over 300 Major Manufacturers m 99 of catalog products ship the same day B Lowest prices guaranteed or we pay 10 J AMECO ELECTRONICS SEMICONDUCTORS N PASSIVES INTERCONNECTS Save 30 or more Looking for killer deals Jameco buyers often find Factory Overrun
169. nected to the same ground as the application It is also useful to protect the development tools from electrical spikes that often occur in some applications such as motor control applications Includes the J Link J Link GDB Server and the J Link Flash Download wWwWw segger us comy ncu html J Link Non Commercial NCU Bundle www segger com Issue 217 August 2008 11 NEW PRODUCT NEWS EVENT DRIVEN FRAMEWORKS FOR EMBEDDED SYSTEMS Quantum Platform QP version four enables the building of well structured embedded applications such as a set of concurrently executing hierarchical state machines UML state charts directly in C or C without big tools QP consists of a universal UML compliant event processor QEP a portable real time framework QF a tiny run to completion kernel OK and software tracing instrumentation QS Current versions of QP include QP C and QP C which require about 4 KB of code and a few hundred bytes of RAM and the ultra lightweight QP nano which requires only 1 to 2 KB of code and several bytes of RAM QP can work with or without a traditional RTOS or OS In the simplest configuration it can completely replace a tra ditional RTOS QP includes a simple non preemptive scheduler and a fully preemptive kernel QK QK is smaller and faster than most traditional preemptive kernels or RTOSs yet offers fully deterministic preemptive execution of embed ded applications QP can m
170. nsmitted on a single line Com mon examples of multichannel receivers are dimmer packs with mul tiple AC outputs and moving lighting that uses multiple channels to control the intensity x axis y axis and color of the light Because DMX often involves long cable lengths and multiple receivers along the length of the cable signal integrity is important to prevent bit errors Using the proper impedance cable and terminating the end of the cable with a matched resistor will elim inate most signal integrity problems ADVANTAGES OF THE DMX PORTAL Earlier in this article I described the typical lighting board style of the DMX controller When using this type of controller to create a light show Configuration EEPROM 8 MHz RC oscillator RS 485 XLR add on board General purpose O the parameters of the show are typi cally entered into the controller s memory as scenes A scene is basi cally a snapshot of the current state of all the DMX channels in use When finished the show consists of a large number of these scenes which can be recalled in a timed sequence to gener ate changing lighting similar to flip book animation The aforementioned method works well for some applications but there are situations where it has disadvan tages One example is architectural light ing in a building such as a restaurant Restaurants typically have many rooms and tend to keep the lights lower for din ner than they do
171. nt values for the 8 data bits but it usually con tains a value of 0x00 to indicate that the following data slots represent individ ual channel data Delays may be added between any of the data slots as long as the data lines remain in the high MARK state and the delay does not exceed 1 s The optional delay is useful because it allows time for the processor to attend to other tasks periodically dur ing DMX transmission The only limit on the delay is that the next frame must be sent no more than 1 025 s after the start of the previous frame This www circuitcellar com DMX frame 11 96 ms minimum Break 88 US minimum lt 44 US p lt 44 US gt lt 44 US gt RS 485 was designed to be a multidrop inter face that allows multiple receivers to be on a single line The DMX512 A specifi cation allows up to 32 receivers on a single line without buffering the sig nal Each receiver 44 ps gt Minimum of 22 668 ms if all 512 channel slots are sent Figure 1 The DMX protocol transmits data in frames that consist of an 88 us break an 8 us mark after break and up to 513 data slots The start code defines the type of data contained in the start slots following it which makes the DMX protocol flexible enough to control different types of devices over a shared cable requirement ensures that data on the DMX line is always refreshed at a mini mum rate Many programmable lights are designed to go into a low
172. ntly control of the phase of the input voltage is required This is realized with space vector modulation SVM SVM uses mathematical coordinate sys tem transforms to simplify motor control by making the stator phase currents appear as DC values under steady state condi tions The two transforms used are the Clarke and Park Transforms First two of the phase currents are measured and used as inputs to the mathematical model The third phase does not need to be known because the sum of the three phase currents should be zero The currents can be represented as time varying vectors in a three axis 120 sepa rated coordinate system To simplify this the Clarke Trans form represents the three phases as two time varying vector components thus reducing the coordinate system to a two axis system The Park Transform further simplifies by chang ing the stationary coordinate system with time varying vec tors to a rotating coordinate system with stationary vectors thus representing the AC currents as DC value with respect to the axes The rotating reference plane is required to spin at the speed of the stator current which is synchronous with the rotating magnetic field of the stator These quantities are spinning slightly faster than the rotor This is known as slip and is required to induce a magnetic field in the rotor With the motor s time constant usually given by the manufacturer the slip frequency can be calculated Then when com
173. ny imbalance is proportional to the strength of the magnetic field passing through the element perpendicular to its other axis Zz Additional circuitry within the Hall effect sen sor configures its function see Figure 4 Hall sensors are available to measure the magnetic strength to sense the presence of a magnetic field or to flip flop with a magnetic field s polarity reversal Another import use for the Hall effect sensor is to indirectly measure the cur rent in a wire by measuring the mag netic field produced by the current in that wire In this project I want to sense the presence of a magnetic field from a magnet over a minimum dis tance of approximately 1 to 2 For this operation I chose the Alle gro MicroSystems A3113 a micropow er ultra sensitive omni polar Hall effect switch Typical switching char acteristics with hysteresis are 40 gauss G on and 32 G off Note that gauss is the unit of magnetic flux density B The Earth s magnetic field is approxi mately 0 5 G The local hardware store had a small display of various magnets and I picked up a pair of ceramic magnets about the size of a domino I connected one of the Hall effect devices to a 5 V supply and monitored the device s open collector output with a 47 kQ pull up I found the magnet triggered the device right around 2 from it Perfect This veri fied that the devices were acceptable for my design criteria To prevent an
174. oard the PID parameters must be prop erly aligned If the motor does not respond well to input like stepping on the accelerator there needs to be alter ations to the PID control loops The proportional gain of the controller determines the maximum output level of the control loop If the propor tional gain is too low the output of the control loop will never reach the set value of the input If the proportional gain is too high the output will oscillate and may become unstable An ideal output from the proportional stage will closely follow the desired value without any oscillations or ringing when it reaches the steady state The integral stage is meant to reduce the steady state error but integral gain can introduce ringing and overshoot The derivative stage is meant to reduce the ringing and overshoot but derivative gain can introduce steady state error An ideal Issue 217 August2008 27 balance between integral and derivative gain can be achieved through trial and tuning to give an optimal response The spatial vector modulation software that we down loaded from Microchip contains three PID loops One loop controls the flux field of the stator the second loop controls the torque current in the stator and the third loop which contains the two previously mentioned loops con trols the angular velocity of the rotor When you input a velocity demand or input a setpoint acceleration decelera tion on the potentiometer
175. ock it loads the data bytes into memory starting at the specified target address and then executes a subrou tine call to that same address The INIT block code must finish with a return instruction in order to allow the Boot ROM to continue processing blocks BUILDING THE SOFTWARE Blackfin software is built in the usual way compile assemble link and load The result of compiling or assembling source files is a set of object files The linker is used to com bine object files into a single exe cutable image which is stored in a file that has a DXE extension The loader converts one or more DXE files into a single loader file LDR extension that can be stored in a boot device and contains the blocks that the Boot ROM will process Among other things the loader omits information in the DXE file that isn t needed such as debugging symbols and other meta data The loader includes the important feature that it can combine multiple DXE files into a single loader file It does this by inserting an IGNORE Analog Devices Blackfin DSP Boot mode block at the beginning of each one This IGNORE block includes a 4 byte data field that contains the total length of the entire set of blocks that represent that particular DXE file If a second stage bootloader or other soft ware wants to skip over the DXE image it can simply read the IGNORE block and then add its value to the EEPROM address pointer which will th
176. oduce only 250 mV If the response varies inversely as the square of the distance doubling the distance reduces the signal by a factor of four At 16 mm the signal drops to 60 mV IR LED amp BPv23 a hae 10 Range mm im Filter Ranpcrma ni Tm TEAM N B d pola Fitter my S 5 2 3 4 Times mms Figure 2 The blue trace represents the sum of the 120 Hz and 8 kHz signals measured in volts on the right hand axis The brown trace shows the output of the four pole filter measured on the left hand axis with all traces of the interference removed Note the 1000 1 ratio of the interference to signal voltages Suppose the signal feeds an 8 bit microcontroller ADC with a 3 V refer ence The resolution will be 1LSB 11 7 mV 5 At that range the signal amounts to just 5 LSB of the ADC s range which is probably down in the noise level More distant targets will be invisible but you can t increase the gain because there s no headroom for larger signals Obviously we need more circuitry DEMODULATION AND DISTANCE A photodiode has a nearly linear rela tionship between incident light power and photocurrent which means that a given change in illumination produces the same change in photocurrent regard less of the overall light level In practical terms the photodiode produces the same current difference between LED on and LED off in sunlight as it does
177. off set 600 uA sine wave at 120 Hz simulat ing a twice as bright as the sun fluores cent lamp shown by the smooth blue trace in Figure 2 You cannot see the 2 uA square wave modulation from I1 that simulates the photodiode s response to the LED but it s superimposed on that trace from t 0 to t 2 5 ms The purple trace shows that the out put of U2 with only two poles of filter ing still has a significant 120 Hz compo nent The brown trace is the output of U3 with only the 8 kHz modulation remaining Notice how the output requires about 1 5 ms to reach full ampli tude then tapers off after the modulat ing signal stops Obviously the firmware must take those delays into account when it samples the filter s output I used 5 resistors and 10 capaci tors so the as built filters wound up at 8 7 kHz In actual use the firmware would measure the true center fre quency and adjust the LED modula tion to suit I just tweaked the func tion generator frequency I measured the response of the two sensors as a function of distance and plotted them on log log axes in Figure 3 The slope of a straight line with log log axes equals the coefficient b of the exponent in the relationship yeu 6 An eyeballed straight line fit to the right hand asymptote of the SMD curve has a slope of AY _ log 10 0 1 b 2 x log 1 5 15 7 The PBV23 curve is slightly steeper perhaps because a glint on the capaci tor acts a
178. oggle the output each N cycles Calculate N for the output to be as close as possible to the required 7 117 Hz Here you can have either 7 122 Hz i e 5 MHz 702 or 7 112 Hz i e 5 MHz 703 That isn t too bad but it s quite far from the target and you can t program a fractional count on a timer This is where DDS helps Imagine another approach configure the on chip timer for an interrupt at any frequency but significantly above 2 x 7 117 Hz Spectrum log scale N 16 P 12 B 16 W 5 166 AA Spectrum log scale N 16 P 12 B 16 W 5 167 0 10 000 20 000 30 000 40 000 50 000 60 000 AN iA 10 000 20 000 30 000 40 000 50 000 60 000 e g 50 kHz At each interrupt add a fixed amount W to a 16 bit phase regis ter convert it to a sine using an 8 bit ROM based look up table and send the value to a DAC Then filter it with a 10 kHz low pass filter Refer to the schematic in Photo 1 in which I have just used a simple 4 bit passive R 2R network as a DAC and a pair of Microchip MCP6002 op amps as a buffer and low pass filter If you need a square signal you can simply route the filtered signal back to the comparator available inside the PIC The associated source code fully coded in C using the free Hi Tech Software PICC Lite compiler is available on the Circuit Cellar FTP site and is no longer than one page You have built an actual DDS and you can generate any frequency calculated as
179. ogic Systems We use our stuff Visit our TS 7800 powered website at www embeddedARM com 4 TASK MANAGER Hone Your Embedded Development Skills you are looking for up to date information about embedded devel opment techniques and technologies this is the issue for you Our fea ture writers and columnists present in depth articles about several design projects and advanced technologies that will help you take your embedded development skills to the next level Beginning on page 14 Matt Ernst explains how he harnessed the power of a WIZnet Ethernet interface and a Microchip Technology PIC microcontroller to build a DMX lighting controller The system enables him to remotely control distributed lighting systems As you know most of the ground breaking intelligent energy solu tions of the 21 century will teature well designed integrated embed ded technologies During the past several months we ve been featur ing such projects in our Intelligent Energy Solutions section This month s project is the electric vehicle inverter described in Electric Vehicle Inverter Design p 22 The innovative design enables you to power AC induction motors Do you have a design that needs to be updated in the field in order to support bug fixes and other features for specific end user apps If so check out Dave Tweed s two stage bootloader that adds additional capabilities to the native boot processing of the Blackfin chip p 34
180. oid return ing NAK Immediately after sending a packet of data refill the endpoint buffer and arm the endpoint for the next transaction For the fastest response configure the endpoint to trigger an interrupt after sending data When receiving data from the host avoid returning NAK Immediately after receiving a packet of data retrieve the data from the endpoint buffer and arm the endpoint for the next transaction For the fastest response configure the endpoint to trigger an interrupt after receiving data On the host be aware that setting RS 232 control lines or changing the parity type or other parameters can be slow compared to performing the same operations on an internal serial port To perform these actions on a USB vir tual COM port device the host must send a request in a control transfer il Jan Axelson is the author of USB Complete Lakeview Research Third Edition 2005 Serial Port Complete Lakeview Research Second Edition 2007 and many other books and articles about hardware interfacing You can reach her at jan Lvr com Lakeview Research Links to CDC Firmware www lvr com serport htm USB Implementers Forum USB CDC Specification www usb org developers devclass_docs approved FT232R USB UART and FT245R USB FIFO Future Technology Devices Interna tional www ftdichip com System on Module Internet Appliance Engine SoM 9260 RES Up to 60 Digital GPIOs s 10 100 B
181. on t have asynchronous serial ports don t need to support these requests and notifications The SET LINE CODING and GET LINE CODING requests set and request the bit rate number of stop Tem Payload EA Claes request IN x21 amp SETUP Y raam L re IN traneaction No data Ok Mo data CRIT transaction G Class request OUT 0x22 K SETUP transaction E M trareacbon in data 3 Class request OUT ict SETUP S rear K CRT transaction EE M traneaction h o d b de b da Ro de b ALK in data Photo 1 The USB communication devices class defines requests that set and get port parameters and control line states Ellisys USB Explorer USB analyzer display 76 Issue 217 August 2008 ACK B bytes 21 22 00 DD 00 00 00 po DE 7 bytes 80 25 OO 00 00 00 08 ALE 8 bytes 21 2000 00 00 00 D7 00 ACE 7 bytes 80 25 00 00 00 00 06 Listing 4 The INF file for a CDC device must include the device s USB vendor ID VID and product ID PID In this listing VID 0925h and PID 9060h Manufacturer MFGNAMEZ Lakevi ew Lakeview ADESCRIPTIONZ Drivertinstall bits parity and number of data bits Photo 1 shows host and device data for these requests The second byte in the setup transaction is the request number When an application changes a port s parameters the host issues a SET LINE CODING request 20h to the device The OUT transaction contains the line coding data T
182. on E mail adcopy circuitcellar com with your file and digital submission or send it to IDEA BOX Circuit Cellar 4 Park Street Vernon CT 06066 For more information call Shannon Barraclough at 860 875 2199 The Vendor Directory at www circuitcellar com vendor is your guide to a variety of engineering products and services www circuitcellar com ET dD MATH PACKAGE s Improve floating point speed without increasing hardware cost Replaces compiler math functions Intrinsic functions 2 3X faster Complex functions 5 10X faster In assembly language for speed Many processors supported Conforms to IEEE 754 Full source code no royalties www smxrtos com RSE SW From TSI Import Eagle libs and Designs Buy Online www pcb sw com Import any of the big three using Intelligent Gerber Download the FREE Demo from the web PromCode Te Micro Digital Inc mer yi ber ine D0506 QUALITY PRODUCT FAST DELIVERY COMPETITIVE PRICING Aluminum Backed PCB Single amp Double sided SMOBC RoHS LPI mask Through hole or SMT Nickel amp Gold Plating Routing or scoring Electrical Testing Artwork or CAD data Fast Quotes Flex Circuits JLSAR INC 9901 W Pacific Ave Franklin Park IL 60131 lt Phone 847 233 0012 Fax 847 233 0013 www pulsar inc com sales pulsar inc com SPECIAL OQOFEEEH 10 PCS 3days 1 or 2 layers 249 10 PCS Sdays 4 layers 695 up to 30sq in ea includes tooling artw
183. ook a lot like random noise However if you were to take a simple R C filter and apply it to the PRS compare out signal it would result in a stable voltage Thus a PRS module s compare output may be treated as a PWM There is only one conceptual difference between the two A PWM s output is defined by its duty cycle or pulse width when fil tered this becomes voltage A PRS module s compare output is defined by its probability value to be above or below the compare value over time when filtered this becomes voltage as well To be more specific once the PRS module has been properly initialized and seeded for the desired range its seed register becomes the compare www circuitcellar com Six pages RAM 97 ms 113 ms 128 ms 145 ms 163 ms 180 ms 195 ms 210 ms 231 ms 245 ms 262 ms Sampling frequency 15 625 kHz 13 393 kHz 11 719 kHz 10 417 kHz 9 375 kHz 8 523 kHz 7 813 kHz 7 212 kHz 6 696 kHz 6 250 kHz 5 859 kHz 0 pages RAM 170 us 170 us 170 us 170 us 170 us 170 us 170 us 170 us 170 us 170 us 170 us One page RAM 16 ms 18 ms 21 ms 25 ms 28 ms 30 ms 33 ms 36 ms 39 ms 41 ms 44 ms Two pages RAM 32 ms 38 ms 44 ms 50 ms 55 ms 60 ms 66 ms 73 ms 78 ms 82 ms 88 ms Three pages RAM 49 ms 56 ms 65 ms 74 ms 82 ms 90 ms 98 ms 107 ms 115 ms 124 ms 131 ms Four pages RAM 65 ms 76 ms 86 ms 98 ms 109 ms 120 ms 130 ms 141 ms 152 ms 163 ms 174 ms Five pages RAM
184. ork L P I mask amp legend CIRCUIT CELLAR 800 366 2491 sales smxrtos com USB Add USB to your next project it s easier than you might think e USB FIFO up to 8 mbps e USB UART up to 3 mbps e USB Microcontroller boards pre programmed with firmware e 2 4GHz ZigBee amp 802 15 4 RFID Reader Writer Absolutely NO driver software development required www dlpdesign com DLP Design Bluetooth 1SPP 1SPP Demo Board PB 1SPP Peripheral Board The Bluetooth 1SPP Boards provide a quick and easy method to wirelessly connect two computers via a standard DB9 serial port or a standard USB port The host accesses the BGB203 via a physical UART interface that can be configured for a variety of characteristics including baud rate word length parity stop bits RTS CTS flow control and DTR DSR flow control Both kits may be purchased directly from Digi Key The 1SPP Demo Kit consists of two 1SPP boards and cables Digi Key PN 622 1020 ND The PB 1SPP is Digi Key PN 622 1021 ND The PB 1SPP would most likely be used in pairs and must be utilized in conjunction with the USB Dongle PN 622 1007 ND FDI also provides low cost demo kits for NXP ARM7 LPC2xxx LPC9xxx and ICP ISP FLASH programmers FDI www teamfdi com VISAIMCTAmex Future Designs Inc 2702 Triana Blvd Huntsville AL 35805 256 883 1240 Fax 256 883 1241 Issue 217 August 2008 87 Digital Core Analog Compatibility
185. ough the architecture For instance less code density translates directly to more cache fills and spills And a 32 bit op code means 32 signal transitions every instruction cycle just to convey the same information that could be packed into many less What s that do to power consumption Even considering the memory mega hertz and megawatts are free mentality of the RISC era the inefficiency proved intolerable for blue collar embedded applications Thus it wasn t long before the architects retrofitted their designs with schemes to improve code density In ARM s case they came up with Thumb mapping a 16 bit op code facade onto the 32 bit architecture In legacy ARM chips Thumb was a mode i e the programmer was responsible for deciding Program CIRCUIT CELLAR Low registers High registers status register which portion of the application code should use 16 or 32 bit instructions and overtly managing the transition in software Kind of a hassle so the new Cortex designs returned to the tradi tional i e CISC solution with the variable length i e 16 and 32 bit no modes Thumb 2 instruction set The Cortex M1 relies on the 16 bit instructions comprising the intersection of the ARM and Cortex instruction sets plus a few of the Cortex 32 bit instruc tions presumably those that are most application critical e g long branch yet don t hamstring the FPGA imple
186. ous signals on the output spectrum It is interesting to compare these characteristics with a synthesizer www circuitcellar com based on a PLL with programmable dividers A integer PLL with its single divider can t have simultaneously fast tuning and a fine frequency resolution which are always in opposition Even with fractional PLLs that have two dividers you will usually get only kilohertz range frequency steps and tuning to a new frequency will take tens or hundreds of microseconds However a PLL can be used to gener ate an output signal far above its refer ence frequency and its output is usu ally clean except for when it s close to the center output frequency or its har monics There aren t any digital spu rious frequencies like with a DDS Based on this comparison you will deduce that a PLL VCO combination is usually more suited to local oscilla tors where high frequencies and clean signals are a must A DDS finds its key applications as a modulation source where agility is most impor tant However DDS chips have gotten cleaner and cleaner over the years and nobody would have imagined seeing a 1 GHz DDS chip for tens of dollars a couple of years ago For the best of both worlds there are chips with both PLL and DDS cores So stay tuned things can change quickly Now it s your turn You should be ready to put a DDS in your next design either as a piece of silicon or some lines of firmwar
187. p uGF bit ChangeMode 0 synchronize angles OpenLoopParm qAngFlux CurModelParm qAngFlux NqRef amp VdRef not used CtriParm qVqRef 0 CtriParm qVdRef 0 CIRCUIT CELLAR OpenLoopParm qVelMech CtrlParm qVelRef calc rotational angle of rotor flux in 1 15 format just for reference amp sign needed by CorrectPhase CurModelParm qVelMech EncoderParm qVelMech CurModel www circuitcellar com lt Listing 2 This code is from the MCP2515 c file s i der s code excerpt The function gets the slider array from the LabVIEW interface over the CAN bus and sets the PID parameters for the motor control for slider count 0 slider count lt 8 if tempLcount OxFF amp amp temp count 1 OxFF get each slider value temp1 1 temp1 2 temp count 2 temp count 3 check sum templ l1 templ 2 add id number templLO slider count 0x0B first one is OxOB templl3 check sum templ 0 new check sum one shot mode for sending PID parameters CAN2510BitModify 0OxOF 0x08 0x08 one shot mode send data sent CAN2510WriteStd 0x00 CAN2510 PRI HIGHEST 4 templ returns 0 1 2 to indicate which buffer 1 if no success Delay10KTCYx 5 10ms CAN2510BitModify Ox2c Oxlf Ox00 reset all tx and rx flags in canintf check sum 0 slider count tt close if temp count count t close slider loop count 0 reset count A A AP CIRCU
188. pared to motor velocity the slip frequency will give an angle that is used to align the rotating plane with the stator s current value The last part of the transform process is to invert the calculated transform parameters back to values that the switching circuitry can use This generates the PWM code This is also the first advantage of SVM The most critical part of these transformations is that the components that make up the transformed current vector determine the torque and rotor field Now the torque can be independent ly manipulated to provide smoother faster dynamic control of the motor Another advantage of SVM is the ability to reduce THD and switching losses by using an algorithm with the fol lowing switching rules the trajectory of the rotating vector should be a circle only one switching per state no more than three switchings in one sample time and the final state of one sample must be the initial state of the next sample This is known as conventional SVM and the algorithm maintains symmetry in the switching waveforms This symmetry is responsible for better performance due to reduced harmonics Lastly SVM can provide a high modulation index 0 907 whereas sine wave PWM can have a maximum modulation AE ru XN vww circuitcellar com _ Potentiometer speed pee m CIRCUIT CELLAR Torque reference dsPIC MC PWM LES O Lia Flux M SVM pee p reference Field weakening Current
189. power state if no DMX data is received with in a certain amount of time effective ly building an automatic power switch into the protocol The physical layer of DMX is a five wire interface using a five pin XLR con nector Pin 1 is Shield ground pin 2 is Data pin 3 is Data pin 4 is Optional Secondary Data and pin 5 is Optional Secondary Data The DMX specification requires the use of a five pin XLR connector The connector pro vides primary and secondary RS 485 data channels The data lines pins 2 and 3 use the RS 485 signaling specification also known as EIA 485 The secondary data channel pins 4 and 5 is almost never used in practice and is the biggest source of differences among vendors Prior to the DMX512 A specification vendors sometimes used a three pin XLR connector and did not include pins 4 and 5 at all Three pin XLR connectors are commonly used for microphone connec tions and this practice allowed people to accidentally connect DMX and audio devices potentially damaging equipment RS 485 also requires cable that has 120 O differential impedance Standard microphone cable does not have this impedance which can lead to poor signal integrity and data errors Other manufac turers sometimes used pins 4 and 5 to deliver power a practice that is also pro hibited by the DMX512 A specification www circuitcellar com may respond to one or more of the 512 DMX chan nels that can be tra
190. r between handling either the reverb or pitch shift algorithms and the potentiometer scanning so much is possible With a communications scheme in place you can control the mixer and reverb pitch shift remotely from anoth er console Add a wireless PSoC to the design and you can have some wireless control over your mixer and DSP With a larger package it would be relatively simple to add a standard LCD with the LCD user module to the project The PSoC could control it directly This would eliminate the need for a serial terminal to display the gains although both could be simultaneously active It also goes without saying that you can add all sorts of buttons to a larger package This would enable you to con trol more functions at will You could use a separate Store Set button instead of the double button press currently in place Buttons to retrieve the next and previous sets would be good Perhaps a separate button for retrieving each set would suit your particular design bet ter In such a configuration holding said buttons could give the command to store to that particular set Or there could even be four separate Store Set buttons The sky is the limit START YOUR PROJECT The purpose of this series was to introduce you to some handy design techniques and teach you how to implement some common product features You can now design an eight channel mixer with 15 gain adjustments all eight input gains four microp
191. r to the Why Cortex M1 question is that it delivers a lot of bang for less bucks i e less sili con and thus less power too Table 1 compares Actel s ARM7 and Cortex M1 implementations and you can see the www circuitcellar com difference is nontrivial Size wise the M1 is significantly smaller than the ARM In fact the 32 bit M1 is only slightly bigger than an 8 bit 8051 soft core Even more notable is the speed difference with the M1 maximum clock rate fully twice that of the ARM7 You can imagine the M1 designers were asking themselves How can we carry forward the essence of ARM7 and M3 yet streamline for a better fit on an FPGA The answer they came up with is summed up in one word Thumb A bit of a history lesson is in order Back in the RISC renaissance of the 1980s when ARM was still Acorn RISC Machines computer architects latched onto the concept of fixed length 32 bit instructions It kind of made sense at the time I guess and ARM was not alone in this But mean ing no disrespect it was a dumb idea One truism is that computers execute some instructions far more frequently than others Wasting a 32 bit op code to decrement a register compare to zero or do a short branch makes about as much sense as using a sledgehammer to hang a picture It s more than a matter of just the cost of memory wasted storing fat instructions The bloat ripples all the way thr
192. ray that is sent to the motor control board when Send Parameters is clicked and there is an indication that the data has been received b The real time HMI enables you to observe feedback from the motor shaft speed and graphical representations of the torque and flux Fault and alarm conditions from the motor and motor controller are also displayed messages sent by the daughter board are the PID tuning parameters You can select the PID parameters using slid ers in the LabVIEW GUI see Photo 5a The GUI software assembles and sends all of the PID parameters in one array appending each individual parameter with OxFFFF This allows the firmware on the PIC18F4620 to parse the array and assemble each parameter into a CAN bus message When receiving messages the firmware extracts the data portion of the CAN bus message puts it into a temporary buffer and then puts the data onto the UART to be received by the GUI Because we aimed to minimize the delay of data handling time and make the GUI as real time as possible we processed all of our daughter board s incoming messages in the LabVIEW application The HMI handles the incoming string of data using case statements to parse the array and determine the type of data arriving before sending it to the appropriate gauge or graph on the GUI see Photo 5b As the electric vehicle becomes a more viable alternative for transportation this project will be referenced as one way to help with the
193. re allowed to run the core a restriction enforced by the design tools as well as the usual legalese Even the truest of believers has to admit the last place you ll ever find a soft core is replacing the big iron com puter chips such as the x86 under the hood of your PC Similarly at the low end it s hard to imagine an FPGA with soft core solution ever displacing a buck or less MCU as much for reasons of system cost as the chip price itself My take is that middle of the road applications are where soft cores make the most sense Modest per formance expectations mean that the soft core disadvantages don t rise to the level of showstoppers At the same time there s enough functionali ty required to garner meaningful bene fit from the soft core concept So why Cortex M1 After all Actel already offers an equivalent line up using a full fledged ARM7 soft core And for that matter what about ARM s spiffy new Cortex M3 core already making the rounds of standard MCU suppliers A key point is that soft core efficien cy and performance are highly depend ent on an implementation that closely matches and fully exploits the under lying FPGA hardware Seemingly innocuous architectural trinkets can sabotage a soft core design if they go against the grain of the silicon On the other hand a soft core that s tailored to fit an FPGA can deliver surprisingly competitive performance and efficiency So the simple answe
194. re programmed up to 100 000 times ISP In System Programming interface Part No VDD Clock Program RAM EEPROM l O Timer PFD Package HT48FO6E 2 2 5 5V 400K 12MHz 1Kx 14 64 x 8 129xX8 13 8 bit x 1 V 16NSOP 18DIP SOP 20SSOP HT48F10E 2 2 5 5V 400K 12MHz 1Kx 14 64 x 8 128 x8 19 8 bit x 1 V 24SKDIP SOP SSOP HT48F30E 2 2 5 5V 400K 12MHz 2Kx 14 96 x 8 128 x8 23 8 bit x 1 V 24SKDIP SOP SSOP 28SKDIP SOP SSOP HT48F50E 2 2 5 5V 400K 12MHz AK x 15 160 x 8 256x8 33 cee V 28SKDIP SOP SSOP 48SSOP HT48F70E 2 2 5 5V 400K 12MHz 8K x 16 224x8 256x8 56 16 bit x 2 V 48SSOP 64LQFP Program RAM EEPROM l O Timer Package HT46FA6E 2 2 5 5V 400K 12MHz 1Kx 14 64x 8 128x8 13 8 bit x 1 8 bit x 4 8 bit x 1 V 16NSOP 18DIP SOP HI46FA7E 2 245 55V 400K 12MHZz 2Kx 14 64x8 1289308 13 8 bit x 1 9 bit x 4 8 bit x 1 V l D d HT46F48E 2 2 5 5V 400K 12MHz 2Kx14 88x8 128 x8 19 8 bit x 1 9 bit x 4 8 bit x 1 V 24SKDIP SOP SSOP l 24SKDIP SOP SSOP HT46FA9E 2 22 5 5V 400K 12MHz 4Kx15 128x8 256x8 23 8 bit x 1 9 bit x 4 8 bit x 2 V 8SKDIP SOP SSOP Holtek Semiconductor USA Inc 46729 Fremont Boulevard Fremont CA 94538 HOLTEK SEMICONDUCTOR INC Tel 510 252 9880 Fax 510 252 9885 E mail sales holtek com http www holtek com usa_only html__ this effect using a thin current carrying element in a bridge configuration With a constant current flowing across the element in one axis x the other axis y will be balanced while no magnetic field is present A
195. rely matches its IR reflectivity The reflected light intensity at the Photo 2 A through hole IR LED and photodiode dwarf an SMD proximity sensor soldered wires to the sen sors pads and glued it to a plastic connector shell for the breadboard in Photo 3 www circuitcellar com tran 0 5m 0 10u Jib opamp sub N o o o 2 al a G e si e o Lu zZ w A Filter 4p UA Figure 1 A Spice simulation model captures the essential elements of a modulated IR proximity sensor 11 an 8 kHz square wave current source simulates the reflected photocurrent Current source I2 pro duces an offset 120 Hz sine wave mimicking a fluorescent lamp glar ing on the photodiode U1 converts those photocurrents into a DC coupled voltage U2 and U3 form a four pole 800 Hz band pass filter centered at 8 kHz to extract the modulated signal V1 provides reverse bias for a real photodiode but has no effect on the simulation sensor doesn t vary inversely as the fourth power of the object s distance as you might expect because the source and reflection aren t ideal point sources and the object and receiver aren t isotrop ic A laser pointer s spot on a diffuse sur face forms one limiting case the total power captured by the detector varies nearly as the square of the distance because the laser spot is effectively a point source in the sensor s field of view A mirrored surface angled away from the sensor forms another lim
196. request function ensures the delivery and receipt of incoming packets The MAX2990 also integrates a fast DES encryption decryption coprocessor to enhance data security The MAX2990 combines the physical PHY and media access control MAC layers in a single chip that also inte grates Maxim Integrated Products s 16 bit RISC MAXQ micro controller The MAX2990 includes 32 KB of flash memory to run the MAC code and user defined custom applications plus 8 KB of SRAM for data memory The MAX2990 starts at 8 50 in 1 000 piece quantities Maxim Integrated Products Inc www maxim ic com www circuitcellar com NEW PRODUCT NEWS AUTOMOTIVE BATTERY MONITORING TRANSDUCERS The HAB 60 S is a new family of current transducers for automotive battery monitoring applications These transducers have been designed to measure DC AC or pulsed currents up to 100 A A new ASIC incorporated into the units offers resolutions 2 5 times better than previous models and a two fold improve ment in offset error coupled with a significant reduction in price The transducers use open loop Hall effect technology that simplifies both installation and servicing by removing the need to cut the cable carrying the measured current They provide a PWM output signal proportional to the pri mary current being measured and operate from a unipolar 5 V supply Tempera ture measurement capability can be integrated with the addition of a fourth connection pin
197. rface but this could be easily changed if high through put via the Ethernet interface is required FIRMWARE I wrote the firmware for this project completely in assembly with Microchip s MPASM compiler Even though writing in assembly can be more time consuming and make com plex algorithms more difficult to read I had two reasons for using this lan guage The first was that I wanted full control to optimize the algorithms as much as possible for the PICI8F archi tecture and my specific application The second reason was that I wanted this project to be usable by other peo ple as a basis for PIC or DMX projects Using assembly requires no licensed P To DES connector MAX202 O Serial Figure 3 The PIC development board uses a 40 pin PIC18F4620 microcontroller and pro vides 3 3 and 5 V power supplies It can operate from an input voltage of 6 5 to 35 V and provide connections for a Microchip ICD2 CIRCUIT CELLAR www circuitcellar com Trigger software compilers and facilitates a better understanding of what is going on at the hardware level This under standing helps a lot when debugging code and also helps you write efficient code the first time During the process of writing the firmware for the DMX portal I developed a library of useful macros and subroutines for math string and utility operations The time put into writing and debugging these code building blocks will help reduce the deve
198. rks out so nice ly with the 0 to 128 scaled pitch offset range Plus it s a bit simpler to work with ADD SPEECH Initialize variables and modules Is a new ADC sample ready Convert sample from signed to unsigned and write to FIFO buffer IIR Filter enabled Has FIFO been filled Note The FIFO being filled means the currently set number of RAM bytes has been filled Pass new ADC sample through the recursive IIR filter PRS configured as a DAC is present Read from FIFO buffer and send this value to both the DAC and the PRS output Figure 2 This flowchart illustrates the basic logic involved in creating a reverb DSP effect The algorithm runs alongside the potentiometer scanning It has been isolated in this flowchart for clarity Suppose you don t have a serial ter minal handy for your project but you still want to know what mode is cur rently active There is plenty of ROM left over after all of the aforemen tioned functionality has been imple mented and the required module a and available This is sufficient to have certain events trigger WAV files to play through the reverb pitch shift output channel As fun as copyright infringement sounds I could not bring myself to download and incorporate sound clips Ad d a We Listen Think And Create Digital 5 Distributed E industrial T I O Computing 7 SeaDAC USB Modules Offer SeaDAC USE
199. rom supply to quali ty Just because the water isn t toxic doesn t mean it is palatable The rotten egg smell from sulfur the laun dry staining rust from iron or the numerous other byproducts of natural but nontoxic minerals have a direct impact on the quality of the water we pump out of the ground Extracting unde sired material can be a fairly automatic process Water fil ters softeners mine minerals from the water by various means Filtering is used to remove particulate These can Figure 1 The basic automatic regeneration water softener system comprises easily be seen and removed by a brine holding tank and a computer controlled valve system atop a resin tank simply straining the water The computer initiates a cleaning cycle based on water usage A cam system opens and closes valves to route well water or brine during cleaning inputs through the resin tank to softened water or waste during cleaning outputs using a material with restricted openings Filters Source Pure Water Products www pwgazette com howsoftenerswork htm are available down to 1 um CIRCUIT CELLAR www circuitcellar com 0 01x the size of the human hair The smaller the pores the slower the flow through the filter and the quicker it will become clogged needing to be replaced A filter of 10 or even 50 um may be adequate unless you require protection against water parasites Carbon is highly effective in removing chlorine organic con
200. rtual COM port that applications can access using NET s SerialPort class or other COM port APIs or libraries In this article I will describe how to design and program a USB virtual COM port device with a general pur pose microcontroller with an embed ded or external USB controller The device uses standard USB class drivers included with Windows and other operating systems OPTIONS FOR DEVICES The COM port software interface provides a way for PCs to exchange data with devices for any purpose A classic example is a modem that enables a PC to send and receive data over phone lines and responds to AT Hayes modem commands from the PC Other COM port devices support vendor specific command sets for data acquisition motor control or other uses To communicate with a COM port an application first reserves the resource by opening the port For many devices an application can also get and set port parameters such as the bit rate the number of data bits per word and the flow control 70 Issue 217 August 2008 USB CRASH COURSE Every USB communication is between a host and a device The host man ages traffic on the bus and the device responds to communications from the host USB 2 0 supports three bus speeds 480 Mbps high speed 12 Mbps full speed and 1 5 Mbps low speed A device endpoint is a buffer that stores received data or data to transmit Each endpoint has a number a direction and a wMaxPacketSize value
201. rward to 2000 and my next soft core love affair with Jan Gray s XSOC Building a RISC System in an FPGA Circuit Cellar 116 117 and 118 Gray s hand crafted design was quite elegant and delivered excellent per formance and efficiency Gray also MUR mtm Te www circuitcellar com ported a C compiler laying to rest the historic no tools objection Though Gray s own interests have diversified his web site is still online and remains a useful archive for soft core information and advice www fpgacpu org In the years since the soft core concept has gone main stream with FPGA heavy weights Xilinx MicroBlaze and Altera NIOS fully on board Now Actel and ARM are pairing up as a duet to sing their own version of the soft core tune NVIC Interrupt interface YEAH BUT Wonderful as the concept may be it s time for a little reality checking A soft core starts with a fundamental handicap namely the fact that FPGA gates cost more use more power and are slower than real gates Of course the design in decision isn t as simple as that For instance Friedin s original inspiration for R16 was to pro vide a self test mechanism for an other wise hardware FPGA based subsys tem In this scenario the conventional processor metrics i e price perform ance power didn t matter much and indeed adding an external processor would have only complicated the task It is no surprise that Moor
202. s from some of the industry s biggest names That means savings of 30 and more to you If you find a lower print advertised price for a product we offer just let us know We ll offer you that product for 1096 less than the price you found right down to our cost Order 24 hours a day 7 days a week WWW Jameco cor Urcall8UU 831 4242 anytime ELECTROMECHANICAL POWER portabledesign conference amp exhibition Power Management for a Wireless World Conference sessions Analyst Presentations and Panel Discussions on designing and powering portable low power wireless consumer devices Complimentary Registration we Keynotes Panel Discussions c Technical Seminars 7 Exhibition Lunch Networking Reception september 18 2008 san Jose California Wyndham Hotel Attend for free Register now www portabledesignconference com sponsored by mirasol o Actel X expresstogic a QUALCOMM DISPLAYS ARM7 Cortex M1 Device M7AFS600 M1AFS600 Tiles required 6 083 4 452 Device utilization 44 31 Performance 28 MHz 67 MHz Table 1 FPGAs are finicky when it comes to hosting a soft core Seemingly similar architectures can exhibit quite different results in terms of price and performance understanding that means the core cost is buried in the price of the silicon In Actel s case only specific M1 Enabled versions of Igloo ProASIC and Fusion chips a
203. s a point source B B log 10 0 1 duis dn log 7 40 8 Varying background illumination still produces a relatively small effect that www circuitcellar com the firmware could periodically measure and fold into the calculation Because I m only interested in proximity not actual distance the calculation need not have any great linearity or precision Ambient illumination and voltage limits still set the upper bound for the transimpedance gain of UI but addi tional gain after the band pass filters can boost the AC signal to more tractable levels prior to an ADC or demodulator In fact that s exactly what the fourth op amp in Photo 3 does In any event you should now understand why commercial IR dis tance sensors use modulated IR and why the simple DC sensors shown in datasheets just don t work in the real world Just a little more circuitry can dramatically increase reliability and accuracy use the gain wisely CONTACT RELEASE I m still mulling over how to build my chord keyboard but Spaceman Spiff s SpiffChorder USB keyboard interface mentioned in the Resources section will certainly form part of the solution Greg s keyboard plugs direct ly into the USB port of his Sony ultra portable PC with no need for special drivers or shim code You could of course use a two button chord keyboard a Morse code keyer with iambic dot and dash switches You must send with metronomic precision for accurate machin
204. s all the parts necessary to connect peripherals like VGA keyboard mouse and servos to the Propeller Proto Board or equivalent in Parallax products Hurry Deadline to sign up for a project number is Pictured below from left to right Propeller Proto Board Serial 32212 September I 2008 19 95 Propeller Proto Board USB 32812 39 95 Propeller Proto Board Accessory Kit 130 32212 14 95 mer oy Tre 4 2 LUm E Eg ig F mun ee mo p m h Pa LE uj TUDE hms E E En EE a a h m r e 9 R m e KI r ITE H k c dala ma NN 99 8 9P EAL EE Er zx LE E E L I E E EE EE NN ee EE m iF PDUEDTTYTICTCPITIITITVITIIPTAXIIEITEREXEIXIEI IIT i Bao ogo o ogo ooo 0 d DT DDGUU GE H et 88009909 a ee QD a e EAR mimi mimg di iam m E n a a A a GD if LAGE E K KLE LAL Feber Gee eee MGD GGR M 1 ooo l i pd Oe ee Pe TTET T E GeO boeogocoteggagonepgoo IO DOOD DE H D aiaa e 0 5 rT tee em E E Dooocpgnooogcgrprovgg obrsogobrLzcecadgoempbrzuzc Re Y E EK X X 3 1 0 R X 2 R E E Bf nimi c G T LEE dl em d E i i E i E E E E d ST b i d D DG i ik w ra cpm Sa d re 3 LIMEN E 9 0 A G GGD a lel elel ca c CE OO GDG EDD g SOUS O Om uunc Ox5 og Qe pM E a GGCD900C C0 rernm Poo eo oe we T LC Y E E E E E 8 2 L z RE D Ec do ee vc GDG eet Cea a a w g Seo eee OF reese I Ia ee ag m o BEEN GGD es ea z TO ToD D p p 2 ii E a fo et ee AE tec eo ee ee ENTIER DCD
205. s will keep you up to date on Circuit Cellar happenings Stay in the loop t It s free Register now It s fas www circuitcellar com Expand Your I O with Rabbit RIO Versatile Device with I O Options Add functionality WITNOUT sa U Drocessol Chat es Multiple P Interfaces Ada 38 1 0 Configure tor PWM TRIAC Input capture CIRCUIT CELLAR ar decode LESS Rabbit RIO Programmable I O Application Kit for 5290 Order Online At EET cee Issue 217 August2008 21 INTELLIGENT ENERGY SOLUTIONS Electric Vehicle Inverter Design Build A System For Powering AC Induction Motors EFFECTIVE USE OF NDTOR CONTROL RESOURCES Mie ded Control Aa n Contest by Dan Hall Tristan Kasmer Doug Krahn Adam Mcintyre and Dena Ponech T world is in the process of advancing alternative sources of energy and the concept of electric vehicle EV conversion is becoming more and more popular But any one interested in this concept will discover that the process of converting a gas powered vehicle to electric power is fairly cost prohibitive This challenge led instructors in the Electronics Engineering Technology program at Camosun College in Victoria BC to pitch the idea of an open source EV conversion kit to our class to take on as our final project We accepted and the EV Drive Team was formed The open source concept of an EV design has numerous benefits such as acc
206. se you wanted to add some DSP to one of the mixer s audio chan nels The PSoC is certainly capable of this feat There are some digital and analog resources left over and many options to accomplish some basic DSP In general any DSP effect com prises three components an input to create digital data an output to repre sent the result as an analog signal and the effect algorithm altering the sam ples in between ANALOG TO DIGITAL DATA The input can be one of many types of ADCs available in the PSoC Some are not suited to audio because their potential sampling rates are too low to properly represent audible sound The choices involve trade offs between sampling rates sample resolutions and required processing time By migrating the design to a Cypress Semiconductor CY8C29466 PSoC you end up with two times the ROM eight times the RAM and an advanced Type 2 decimator that 44 issue 217 August 2008 allows for the new high speed and low overhead DelSig ADC The DelSig ADC module requires another two digital blocks and one analog block for a single order decima tor Nine bit resolution 128x decima tion rate was selected in favor of the next step down 7 5 bit resolution 64x decimation rate to better fill the out put resolution which will be 8 bits discussed later One arithmetic shift right of the incoming 9 bit value and you have a full 8 bit sample With a 128x decimation rate and a clock rate of 4 MHz th
207. sed It is not a simple quency from DC to nearly 10 MHz generator is that you can use it for any DDS Simulation Phase register length 16 bits Phase maximum value 65 536 Phase increment 9 058 Reference clock frequency 1 00 x 10 Hz Reference clock period 1 00 x 1055 DAC Width 8 bits 138 214 11 Hz OUT Phase wheel Figure 3 This spreadsheet simulation shows the phase wheel concept A fixed angle is added to the phase register at each clock pulse Note that each period of the output signal is not identical to the previous ones because the phase doesn t go back to the same value after a full turn www circuitcellar com CIRCUIT CELLAR Issue 217 August 2008 61 below this limit which usually means frequen CLOCK offset offset register register to F 100 For exam AM CLOCK ple look at the datasheet DV for a lab class arbitrary PSK _ Phase signal generator like the pes Agilent Technologies 33220A which is 50 Msps TUM It states maximum sine fre Phase nos to pass quency 20 MHz and increment register register lit i amplitude nien maximum triangle fre quency 200 kHz Now you know why If you need to generate a square signal you will FcLock not have these limita tions because you can Figure 4 A DDS generator can be easily improved to add full digital modulation features including either frequency phase or generate a sine and add a amplitude modulations simple
208. st device verify compliance TR110 EX200 EX260 999 2999 CALL Multiparameter Loggers MinHogger with builtin temp humidity pressure 3 axis accel sensors Customize msmt record parameters send data to PC after or during logging Synchronize multiple loggers merge data to single record MSR145S from 468 Tiny USB Serial World s smallest USB adapters Ready made CP2101 miniboard USB interface to 1 Mbps microUSB HR USBUART 25 29 Easily create mesh networks at 910MHz like Zigbee only better Complete RF solution for fast amp reliable data transmission B915FHtiny 40 SMD WA 73 B915FHtiny 80 SMD WA 73 2 world for unique time saving pro rds LCD display kits Etherne USB cables extenders line wireless boards SMD adapters les video motion detectors ters PLCs Remote MP3 playe 7 ler Check www saelic com High accuracy stability wide range low phase noise leakage serial control Keypad rotary setting TGR1040 10MHz 1GHz FM int ext TGR2050 150kHz 2GHZAM FIWPM 2498 4558 World s Fastest Winner PS5204 2 ch 250MHz Scope with 128 MS s and real time sampling of 1GS s Adv triggering 220MHz spec analyzer and 125MS s waveform gen PS5203 32MS buffer 2237 PS5204 128MS buffer 3360 Handheld Scope Rm Ttt 20MHz or 60MHz rugged hand held USB scope with 3 8 color LCD Built in meter great for your tool kit HDS1022MN 20MHz HDS2062M 60MHz 593 699 SPI Bus A
209. t To send status information the device returns notification data in response to IN token packets on the interrupt IN endpoint A device with no infor mation to send returns a NAK Most devices also respond to class specific control requests that set and get serial port parameters Figure 1 shows a CDC device that functions as a USB to RS 232 bridge The microcontroller s asynchronous seri al port interfaces to a Maxim Integrated www circuitcellar com Conference September 14 19 Exhibition September 16 1 Santa Clara Marriott Santa Clara CA pcbwest com Two day exhibition Free events and sessions Networking opportunities Over 35 conference courses GROW YOUR KNOWLEDGE 2 ha NE J IN THE HEART OF SILICON VALLEY c PCB WEST 00 UP Conference amp Exhibition Media Group Monitoring Applications Just Got Easier C UM es Huey docbmurks Tes gad mia a Mp r E aiia pja Se DR Gee eee pum n Vohicn ik Fori Smarter Embedded Design The RCM4300 RabbitCore module gives you more processing power and memory for your demanding embedded applications that require web interfaces graphics or encryption Data logging applications will also take advantage of the minisD memory cards with up to 1GB of storage It s easy to add the RCM4300 or any qty 1000 RabbitCore module to your pin compatible desi
210. t sampling peri od 60 ms instead of 240 us for the A3213 translates to a much lower operating current But it wasn t avail able at the time I bought these parts I will let this circuit run for a while I will watch its performance I already have some thoughts on tying this information to other data I might collect in the well house Collect being the key word here I can think of a few technologies I want to inves tigate before taking a second look into the pit al Jeff Bachiochi pronounced BAH key AH key has been writing for Circuit Cellar since 1988 His background includes product design and manufacturing He may be reached through the magazine jeff bachiochi circuitcellar com or his web site www imaginethatnow com PROJECT FILES To download code go to ftp ftp circuit cellar com pub Circuit Cellar 2008 217 SOURCES A3113 and A3213 Hall effect switches Allegro MicroSystems Inc www allegromicro com PIC12F510 Microcontroller Microchip Technology Inc www microchip com Issue 217 August2008 59 THE DARKER SIDE by Robert Lacoste Direct Digital Synthesis 101 Need a refresher on direct digital synthesis Robert brings you up to speed by covering DDS theory a few chip based solutions and some firmware implementations W as to the Darker Side If you are a regular reader you probably remember my December 2007 article about using a phase locked loop PLL to generate precise and
211. t types amp 32 bit floating point Based Support Packages RS232 USB and LCD Libraries precaszr rk rera rnt m l a P a Xat benchmark price dsPIC PIC24 additional types eH CO 515 EDI at IE For ARM I hased SHC 48 and 64 bit float Versatile Programmable Module B AS amp int64 Serial FC USB Parallel Interface E H ed euni T IDE with Advanced Debugger AVRIB ASIC Stamp VB Compatible UPC 0 Ieai Urana ANM Multiple Compilation Units Onboard Flash Bima M X5S5cale Fan FX 70 PXAZ55 C Aware Editor Trias ea y MPUS554 MPC5200H MPCSSh TC BRB oS Downloadable TTF Fonts CaldEire ur aas New Project Wizard Z MCFEAdG AD5F BFE17 Pe RA 2 7 of 4 6 TOUCH Calor TET LCD C Metrics ume Ln UR 240x160 or 320x240 resolutions f E Bape Deselopsicnt Eris stiri at 00 gt S Transfiective wi LED Frontlight 2 77 m include SOC Carrier Bowl sothwaer docu as N 7 MG SE am Transmissive wi 154 niil backlight 5 6 will in ME cali aid pliers and LOO F e m SUL module esty ports trom Carrier Brand to fias Visas ud i 1 a 542 colors pr 64 535 colors user Turis h ee aar 1 ov i Minen o A Fh E www ccsinfo com REV z 5 Laon E mrt err re eY Gye Y 702 527 6500 X35 d EAR H LCW Wie hake T Work www Bey ite Sol ag a Wen pleas enm amp 4 sales ccsin lt NAND FLASH ene with FILE SYSTEM Mach Design Services LLC Coming Soon Wear Leveling Garbage Collection Hardware Design A Social Networking Site for P
212. taminants chem icals and undesirable tastes and odors Like the filter cartridge you must replace carbon periodically because it has a finite amount of absorption and will cease functioning once full As water travels through the Earth minerals are absorbed and water becomes harder The extent of hard ness is measured in grains per gallon GPG A grain is a unit of weight approximately 0 000143 lb with 1 GPG 17 1 ppm Water with an excess of 5 to 10 GPG is considered very hard The dissolved minerals can accumulate on surfaces in the form of a hard scale The buildup will eventually clog pipes and may damage water using appli ances These minerals also affect the ability of soap to clean surfaces dish ware and laundry While these are not generally harmful to the body a water softener can remove them and protect your plumbing A water softener that will remove these is based on the exchange of ions An ion is a molecule that has lost or gained one or more valence electrons giving it a positive or negative electri cal charge My system has two basic parts the brine tank and the resin tank with a controller see Figure 1 The tall tank is filled with resin beads typically made from styrene or divinylbenzene As well water passes through the tank mineral ions are attracted to the resin which in turn gives off salt ions Like other filtering devices once the surface area of the beads is covered with mineral ions
213. tant t 2ps 100 x 10 Q 20 x 10 F 1 That corresponds to a cutoff frequency of about 80 kHz 9 ZT T 21T 2 US 2 An 80 kHz bandwidth may suffice for some purposes and be woefully inadequate for others In the latter case you must throw more hardware at the problem Op amp UI in Figure 1 acts as a lin ear transimpedance amplifier with a gain set by feedback resistor R1 Cur rent source I1 simulates the photodiode although it omits all the nonlinearities and real world effects Voltage source V1 isn t needed with an ideal current source but it s a reminder that you must reverse bias a real photodiode Ul s inverting input has a high imped ance and can t supply current to the pho todiode Therefore the photocurrent must come through the feedback resistor and the amplifier s out put voltage will drive that cur rent through R1 Because U1 s noninverting input is at 0 V and feedback maintains the inverting input at O V the output voltage equals the photocurrent times RI the transimpedance is exact ly R1 volts per ampere C1 compensates the op amp for the photodiode s capacitance Finding the exact value requires some tweakage starting from the value predicted from the known feedback resistor R1 the sum of the photodiode capacitance and Issue 217 August2008 41 op amp input capacitance CT and the op amp s gain bandwidth product GBW CT Cl 27 R1 GBW 3 I used an LF41
214. tems has strengthened its support for Microchip s range of 16 bit PIC24 microcontrollers and dsPIC33F digital signal controllers by adding native hardware level debug support through the inclusion of the MPLAB REAL ICE in cir cuit emulator system within its C SPY debugger an integral component of Embedded Workbench Embedded Workbench incorporates a C C compiler assembler linker librarian text editor project manager and C SPY Debugger in a single IDE giving you the advantage of an uninterrupted workflow and a single toolbox in which all components integrate seamlessly The package also features seamless integration with visualSTATE a graphical development tool for creating demanding event driven embedded applications visualSTATE generates optimized ANSI C code from state machine designs based on UML providing advanced verification and valida tion utilities and the C C code it produces is compact and 100 consistent with the system design Using the combination of visualSTATE and Embedded Workbench enables you to increase the feature richness and code quality of an application while reducing implementation complexity and improving maintainability Please contact IAR Systems directly for price information IAR Systems WWW iar com MODULAR TMS320F28x DSC DEVELOPMENT KITS Making it easier to jump start 32 bit based digital power and TMS320F2808 or floating point F28335 control embedded control designs five new Exp
215. that carry appli cation data Two CDC requests SEND ENCAPSU LATED COMMAND and GET ENCAP SULATED RESPONSE and one noti fication RESPONSE AVAILABLE relate to AT commands The CDC www circuitcellar com specification requires abstract control model devices to support the requests and notification A typical generic COM port device doesn t connect to a modem that supports AT commands For these devices the host will never send the requests or require the notifi cation data so device firmware doesn t need to implement them MAXIMIZING PERFORMANCE Following a few guidelines can improve the performance of device firmware For full speed devices set wMaxPacketSize in the bulk endpoint descriptors to 64 to enable the transfer of the most data possible in each USB transaction With a UHCI host con troller if a full speed bulk endpoint s wMaxPacketSize is less than 64 the host controller schedules no more than one transaction per millisecond for the endpoint Full speed host con trollers comply with either the OHCI or the UHCI standard Many PC motherboards contain UHCI con trollers High speed bulk endpoints must set wMaxPacketSize 512 To Got Serial Need Network transfer large amounts of data to the host as quickly as possible use wMaxPacketSize data packets Larger packets mean fewer transactions are needed to transfer the data When sending data to the host in multiple transactions av
216. the ACIM is inductive and if the input frequen cy is decreased the stator currents will increase The input voltage will have to decrease by a proportional amount to counteract the current increase The result is in a relatively constant stator field Voltage K x Frequency This is a simplistic representation of the V Hz profile In reality the relationship between voltage and frequency does not have to be linear and may be adjusted to provide optimal motor performance in some frequency ranges The V Hz method also incorporates feedback from the motor to more efficiently generate drive demand using PID control The actual frequency of the motor is meas ured using a tachometer that is frequently used to calcu late an error signal that is used by the V Hz profile to generate the appropriate voltage and frequency values Finally a PWM code will vary the duty cycle with respect to time to generate a simulated sinusoidal drive signal Photo 4 This daughter board was used to interface the HMI to the control board The control board is connected via a CAN bus and the LabVIEW HMI via USB CIRCUIT CELLAR www circuitcellar com I The drawback of the V Hz control is that it does not handle fast dynamic changes in speed or load well The reason for this is that control of the torque and rotor cur rents cannot be separated and change in drive voltage affects both of these motor parameters To be able to control the torque independe
217. the firmware update protocol in their host CPU Whenever they need new functionality in the IMU we can e mail them an updated loader file and they can install it with out disassembling the system in any Way While many of the details discussed here are specific to the Blackfin boot process I hope that the more general concepts will be found useful on other CPUs as well I want to thank Robert Pinto and Enpoint LLC for their support and the permission to tell you about this aspect of their product David Tweed dtweed acm org is a hardware and real time firmware engi neering consultant who has been work ing with embedded processors starting in 1976 with the Intel 8008 His system design experience includes computer design from supercomputers to work stations digital telecommunications systems and the application of embed ded microcomputers and DSPs He is also a Circuit Cellar project editor and quiz master When not playing with electronics and software he pursues his hobby as an amateur musician playing keyboards and low brass instruments in several community groups PROJECT FILES To download code go to ftp ftp circuit cellar com pub Circuit_Cellar 2008 217 RESOURCE Enpoint GPS Inertial Solutions www enpoint com SOURCES ADIS16350 Inertial sensor and Black fin DSP Analog Devices Inc www analog com AT45DB081D DataFlash Atmel Corp www atmel com www circuitcellar com
218. tive full featured 16 ch 4MB 200MHz sampling memory Sophistcated triggering 12C SPI and UART monitoring Includes clipleads USB cable and software LAP 16128U 299 Mixed Signal PC Oscilloscope 100 MHz Scope and Logic Analyzer lets x you do complex triggering to find hard to E get at glitches spikes etc Huge 4 or CM 8 MS buffer for deep data drilling and zooming Optional built in swept signal generator 2 Analog channels x 10 12 14 bit with more than 60 dB dynamic range 8 digital inputs for mixed signal display trigger CS328A 4 4MS Buffer CS328A 8 8MS Buffer CS700A signal generator 6 1 2 digit 50KS s 2MS mem Opt 16 ch mux Automeasure DC AC 2 4 wire R C Continuity Diode Frequency Period Ratio Temp Sensor High Low Limit Math DM3061 795 Ether IO UDP IP controlled 24 digital I O board 3 x 8 bit TTL ports each independently programmable Connects to any TCP IP Ethernet network Ether lO 24 119 Easy OLED Display 4D Systems Compact economical smart OLED with graphics for stand alone functionality to your project drive from USB or RS232 uOLED 96 G1 89 uOLED 128 GMD1 99 RF Modules RF TX RX Modules simultaneously transmit composite video and stereo audio signals 2 4 GHz ISM band 4 ch RF 5V operation AWM630TX 16 AWM634RX 27 1259 1474 299 USB Bus Analyzers USB1 1 2 0 WiMedia analyzers and now EX260 can test USB3 0 5Gbps too Emulate ho
219. to indicate when the water filtration s brine tank is out of salt I could have done this with a single sensor properly positioned at the bottom of the tank but this project gave me the opportu nity to demonstrate the use of Hall Salt bytes to Get x 8 Water bytes to Get x 8 Temp lt 0 FSR TableStart Temp temp 1 Done with 8 bits FSR lt FSR 1 Figure 6 This application samples and reads the 32 Hall effect sensor inputs via a software SPI routine Two LEDs display pellet and water float heights by blinking a two digit decimal code 1 blink per inch www circuitcellar com CIRCUIT CELLAR effect devices to do measurement and not just indication While the actual level of water in the brine tank isn t important measuring more than one level using the same strip of sensors is a good application If the filtration sys tem breaks down the level of water in the brine tank will be an indicator of potential trouble Because I know that a cleaning cycle normally takes place every x days if the level of the brine hasn t changed in say 2x then I know there must be a problem As it is I use a regulated 5 V wall wart supply to power this circuit plugged into a GFI If I control 5 V power to the Hall effect sensors leave them unpowered when not being sam pled the circuit current will be low enough to run with batteries I could have used Allegro s A3214 for this project Its less frequen
220. to the transducer package Output resolution of the HAB 60 S transducer is 0 03 A with a linearity of 0 2 Electric offset error is typically 0 075 A across the temperature range from 10 to 65 C and 0 15 A across the full range from 40 to 1256 A water tight housing and sealed connector provide full environmental protection in engine compartment applica tions Principal applications are expected to be in the meas urement of battery pack cur rents in electric hybrid and conventional vehicles The transducers are fully certified to automotive standards The HAB 60 S costs 30 LEM www lem com PIC10 12 16 ANSI C COMPILER The C PRO is a new ANSI C compiler with omniscient code generation OCG supporting the PIC10 12 16 MCU family It achieves higher code densi ties and better RAM utilization than comparable compilers for the PIC16 17 without using any C extensions or assembly code By optimizing interrupt relat ed contexts the OCG technology in this new compiler reduces interrupt laten cy by 4096 to 6096 The compiler automatically handles memory banking without requiring spe cial qualifiers It optimizes the size of each pointer variable in your code based on its usage It also eliminates the need for many nonstandard C qualifiers and compiler options and it produces more optimal interrupt context switching code The C Pro compiler also integrates into the MPLAB IDE MPLAB ICD2 and the HI TIDE 3 IDE It
221. tor 2 due to exposure to an external magnetic field 3 and 4 A potential measured across the conductor is proportional to the magnetic field strength Source Wikipedia http en wikipedia org wiki Hall_effect remaining pellets sit in the brine Eventually when all of the pellets have been dissolved and you ve forgot ten to add to the brine tank the regen eration cycle becomes useless and the removal of minerals ceases My house and seven others in the neighborhood receive water through a single community well that just hap pens to be on my property A perfectly working pump and water softener are key to keeping the neighborhood one happy family Guess who gets the call when something acts up The pump storage tank and water softener are housed in a below ground well house Generally this all worked without much intervention Neverthe less I came up with an idea several months ago I wanted the ability to know without having to periodically enter the dungeon pit when the brine tank is empty and when the system fails TWOFER Knowing the depth of the pellets left in the brine tank without having to venture underground is a big improvement Because the water level in the brine tank isn t constant 54 Issue 217 August 2008 weighing the tank to determine the potassium level won t work unless I know how much water is in the tank and can subtract its weight Using electronics inside the brine tank isn t sa
222. tputs 8 ISOLATED digital inputs PortPowered Aux5VDCoutput 189 00 QTY 1 Other Models ADU200 4 Channel Version with RS232 139 00 ADR218 Solid State Version 8 Channel 225 00 ADU100 3 CH 16 Bit ISOLATED Analog Inputs PGA 4 digital O RS232 and 5 AMP Relay Output 199 00 ONTRAK CONTROL SYSTEMS INC PH 705 671 2652 Fax 705 671 6127 www ontrak net CIRCUIT CELLAR TStk is a ruggedized TINI400 chipset in the familiar SIMM7 form factor Upgrade most DSTINI1 TINI390 systems or use our new TILT socket boards TILT Pro is shown above TStik is about 100 and sockets start at under 60 SYSTRONIX full details at www TStik com USB Device Stack Compatible with Windows USB 2 0 Host Class Drivers e Mass Storage e Mouse e Ethernet over USB e Serial e Composite Devices e ARM ColdFire Philips ISP 1161 1181 1362 158x 1761 Low Cost Royalty Free Full Source Code Standalone or RTOS Host and OTG Available Micro Digital Inc RTOS Innovators www smxrtos com usb Incredibly Low Cost USB Chips at HexWax dE USB 232 USB to serial UART smarter W and cheaper than the FT232R USB SPI USB to synchronous serial I2C too USB DAQ Data logger plugs in like a flash drive USB Config Configuration amp diagnostic module USB TakeOff Power take off amp battery charger WattLogic Domestic power consumption logger AnniLogic Anniversary reminder No expandlO USB l O expanders drivers TEAleaf USB
223. trol circuits or the physical zone pipes My initial thought was just to bond a 140 bimetallic sensor on each zone pipe but it was grossly inaccurate The burn er might run for 5 min and the zone pump for 10 but the amount of time for the pipe to warm and cool enough to switch the sensor depends on the rate of heat transfer in each zone too many variables For later analysis and specifically to see if there was any interesting correlation among those variables attached a Xytronics four channel temperature monitor on the pipes But as for connecting the HCS to the furnace was deal ing with the 24 VAC actuator signals Converting a 24 VAC on off actuator signal into isolated contact closure output to the HCS is a relatively easy concept Because there are six actuator signals however doing it with the least current requirement from the furnace power supply was the challenge Ultimately chose to use capacitance reactance Typically used in transformerless power supplies or trickle chargers the technique utilizes capacitance reac tance to limit current in a Zener regulated AC to DC converter The converter s DC output powers a low current reed relay whose isolated con tacts go to an HCS input Certainly could have dug through the junk box for some appropriate opto 22 commercial solution but going back and experimenting with basic electronics was fun for an evening just like reading Circuit Cellar Besides as a home brew electronic answer
224. trom Electronics 91 Micro Digital Inc 1 95 Saelig Co 88 Apex Embedded Systems 90 HI TECH Software LLC 5 33 Microchip 89 Saleae LLC 89 Applied Micro Training 19 HobbyLab LLC 92 microEngineering Labs Inc 90 Schmartboard 7 Atmel 55 Holtek Semiconductor Inc 57 Mouser Electronics 48 Sealevel Systems 49 Bitscope Designs 89 ISP Micro 88 Mylydia Inc 11 SEGGER Microcontroller Systems LLC 65 CWAV 89 90 IMAGEcraft C2 NetBurner 91 Systronix 58 88 CadSoft Computer Inc 19 88 IMAGEcraft 37 Nurve Networks LLC C3 Tech Tools 31 Calao Systems 91 Intec Automation Inc 91 Ontrak Control Systems 2 3 Technologic Systems 79 Comfile Technology Inc 92 Ironwood Electronics 72 DCB West Design Conf 91 Technological Arts 90 Custom Computer Services Inc 64 66 JKmicrosystems Inc 72 PCB Pool 87 Technology Sales Inc 87 DLP Design 91 JKmicrosystems Inc C4 Parallax Inc 89 Tern Inc 90 Designnotes 81 Jameco 90 Phytec America LLC 24 Tibbo Technology Inc 77 EMAC Inc 37 Jeffrey Kerr LLC 92 Pioneer Hill Software 89 Tin Can Tools LLC 80 ESC Boston 17 Keil Software 13 Pololu Corp 71 Total Phase Inc 90 Earth Computer Technologies 37 Lakeview Research 82 Portable Design Conf amp Exhib 92 Trace Systems Inc 19 Esensors 88 Lawicel AB 87 Pulsar Inc 91 Triangle Research Intl Inc 20 ExpressPCB 29 Linx Technologies 63 R4 64 WCSC Willies Computer Software Co 31 ezPCB 88 Loadstar Sensors Inc 21 74 Rabbit A Digi International Brand 47 Wiznet 87
225. ts of a block are connected via wires to the inputs of other blocks or they are connected to control and indicator symbols which correspond to graphical items on the GUI called the front panel Ei l ocessors a up to Bor re pah prog Propeller sets a A standard in support for many commercial pro allowing the DMX portal to support innovative design l l Large Tear Model allows programs grammable lighting fixtures and the same commands I effectively much larger than COG makes it easy to generate complex received support for this application S oy paca persed at lighting effects Refer to the Sources with no extra work The USB DMX downloade section FreeStyler already supports project uses an FTDI chip that appears the USB DMX binary protocol so by as a virtual COM port in Windows Ex DX Portal virtual Lighting Hoard Serial Porti tal Lighteg nard salt Patch Configuration DE frame Buller Lesejs Serial Comemimiration Settings 650 495 9328 FAX 6 FAX 650 493 9329 R E Monitoring Software Wensenanr Applications HVAC Systems Data Centers Laboratories and more Esensors g www eEsensors com 716 837 8719 Photo 4 This application was written to demonstrate how a final user interface for the DMX Portal could be written ocu cadis or es Duos WAHGISSISUISGIT using LabVIEW It provides features commonly found on a standard lighting control board such as level sliders and blackout controls Get 10
226. u have to acquire The Device Knowledge You have to know what the LUTS registers slices CLBs block RAMs DLLs etc can and can t do You have to learn exactly how much local intermediate and long routing is available per bit height of the logic in your datapath and how wide the input and output buses to the block RAMs are You have to learn about carry chain tricks clock inver sions GSR nets bonus CLB and rout ing resources TBUFs and so forth You also need to know the limita tions of the tools What device features PAR can and can t utilize How to make PAR obey your placement and timing constraints and what things it can t handle And how to push on the rope of your synthesis tools to make them emit what you already know you want The Knowledge isn t in any book alas Yes you can read the street CIRCUIT CELLAR maps e g the datasheets and app notes but that only goes so far You have to get out on your scooter and explore Jan Gray www fpgacpu org log aug 02 html theknowledge It s safe to say the soft core concept makes sense for some applications It s also safe to say that considering advances in FPGAs price perform ance and power and the soft cores themselves soft core makes sense for more applications today than yester day and yet more tomorrow Ironically the excellence of the sili con and elegance of the core may not be the deciding design in factors
227. ue 217 August 2008 75 which is a data packet containing less than wMaxPacketSize bytes If the entire transfer is less than wMaxPack etSize the transfer s only data packet is a short packet If the transfer con sists of more than wMaxPacketSize bytes only the transfer s final data packet is a short packet When a transfer has an exact multi ple of wMaxPacketSize bytes the end point returns wMaxPacketSize bytes in one or more transactions until all of the data has been sent The end point then indicates the end of the transfer by responding to an IN token packet with a zero length packet ZLP which is a data packet with no data bytes On a Windows host every CDC vir tual COM port device must have an INF file that contains the Vendor ID and Product ID values and names the software driver for the device Win dows doesn t provide a generic INF file for USB virtual COM port devices as it does for other device types such as mass storage and human interface devices HIDs You can modify an INF file provided with CDC example code Listing 4 is the part of an INF file that specifies a Vendor ID and Product ID for a device SETTING PORT PARAMETERS Besides COM port data devices with asynchronous serial ports often exchange information relating to port parameters status and control signals and error states The host uses class specific requests and notifications to send and receive the information Devices that d
228. uired FTDI also developed its USB functions as LabVIEW Virtual Instruments VIs that are called from our HMI which also made them a good choice for our application For mes sage processing on the daughter board we used a PIC18F4620 with an external CAN bus controller MCP2515 and trans ceiver MCP255 These CAN bus control ICs and the microcontroller are manufactured by Microchip PROTOCOL Communication with the motor controller is through the CAN bus protocol The CAN bus is a broadcast differential serial bus CAN was developed to be a robust communica tion protocol for particularly noisy environments therefore it is already commonly used in the automotive industry Because CAN is a broadcast bus there is no way to send a message to just one specific node All nodes will invariably pick up all traffic However the CAN bus hardware provides local filtering so each node may react only to the relevant messages 5 Because our development did not require a great deal of message traffic and uses only two nodes we chose not to use the CAN bus filters and identifiers We developed our own protocol using headers and identifiers contained Listing 1 This code is from the motor control software from the ACIM c file doCont rol func tion excerpt It reads the speed input demand from a potentiometer on the control board gets feedback from Hall effect current sensors and drives the motor with the option of open loop or close
229. ure 2 ADD PITCH SHIFTING As I was having fun with the adjustable reverb I noticed that there was plenty of ROM left over in the project The reverb buffers had con sumed most of the extra RAM But when the reverb was not in use all six buffers were open for another purpose As it happens I recently took a Z8 Encore based project from an earlier issue of Circuit Cellar and converted its pitch shifting algorithm into a Issue 217 August 2008 45 inc E PGA Lc inD E PGA Ld inA inB inc E PGA Rc inD E PGA_Rd P2 4 External Agnd Ui Ke CY8C29466 out O z SC_Labed SC_Lab SC Led SC_mono out_1 Ke out 2 Ds SC Rab SC_Rabed a 4 MHz max to all SC blocks SC_Red out 3 gt DelSig ADC TMR_pots VC3 TIMER8 n ut J10 C13 0 001u TRV Intercom l C la out Scan pis 10k JJ U JJ U D 0 Az Bu RU n o 4 4 d 4 D H14 1k a U Ea e o C 4 4 C D1 D2 D3 C19 gen l Figure 1 This is the revised mixer schematic It now includes the additional circuitry to support new enhancements DSP intercom WAV playback and mode switching Note that the component count of the project is still low even after these enhancements PSoC project for fun It required only three pages of RAM to implement two out of phase sample buffers and one triangle wave buffer for cross fad ing and worked quite well with two buttons one for up the other for down used to adjust t
230. used The FCSE allows different processes to easily share the same memory space The debugger knows which exe cutable code belongs to each process and can select the appropriate debugging information even though the processes share the same execution address The ARM simulator will also simulate the operation of the MMU and the FCSE This enables code which uses these features to be tested on the developer s PC before being tested on the target hardware It also enables devel opers to explore the operation of the MMU and FCSE without any hardware at all The ARM Development Suite provides a complete and extremely user friendly development environment for the ARM family of microprocessors and microcontrollers with its advanced C C compiler libraries wizards sim ulator source level debugger and the Jaguar USB JTAG debugger interface The ARM Development Suite costs around 2 600 Crossware Products Wwww crossware com ULTRA LOW SUPPLY CURRENT MONITORS Battery life is of the utmost importance in portable applications where it is essential to reduce the amount of supply current the device draws during normal and stand by operation The new LTC2934 and LTC2935 ultra low power supply monitors draw only 500 nA of quiescent current The unique features of the LTC2934 and LTC2935 dif ferentiate them in the low power monitor market and make them excellent choices for single Li coin cell AA AAA and other compact battery pow
231. ut 1 ms to transmit So it is possible to send more than 2 bytes of data over the RS 232 link before one DMX frame refresh is completed This can result in data being lost and com mands that were sent not being processed The best way to maintain a con stant DMX output refresh rate while still being able to tolerate large momentary bursts of command data is to implement the serial interface with a second small low cost microcon troller This would enable the data memory of the second microcontroller to act as a large command buffer It would also make the serial interface as robust as the W5100 Ethernet inter face which already contains a large memory buffer Another approach would be to use an external hardware UART for the DMX output This would eliminate the need for the processor to sit in wait loops to generate the correct data rate It would also enable the proces sor to handle incoming data in the gaps between bytes The downside to this approach would be that the DMX output refresh rate would become dependent on the amount of traffic received on the communication ports This may not be a problem but it would require a bit more care in implementation because the DMX standard requires a minimum refresh rate If too many commands are sent during a frame refresh this rate may not be met For the prototype I used a relatively slow 8 MHz system clock because it could be generated from the PIC18F4620 s internal RC osci
232. ut out a 4 5 hole along one edge which keeps the disks from spinning within the tank while floating atop the brine and riding atop the salt After a couple of trial fittings in the tank I CIRCUIT CELLAR attached magnets to the foam disk and the egg crate disk see Photo 1 The magnets are vertically aligned to one another on each of the disks so when they are in the tank they pass directly behind the Hall effect PCB strips mounted on the tank s exterior The brine can easi ly pass through the holes in the plastic egg crate the pellets cannot Therefore the egg crate rests atop all of the undisolved pellets see Photo 2 While a cleaning cycle is active all of the brine may be with drawn from the tank But it is quickly replaced by the end of the cycle To prevent the two disks from attracting each other I placed spacers on the egg crate to keep the two disks at a minimum of 3 apart The normal level for the water is quite high SENSOR STRIPS To keep the maximum length of this narrow PCB reasonable I used a length of 8 1 This allows sensors to be evenly spaced at every inch and each PCB to report in a single byte one sensor bit inch Because the cir cuit allows daisy chaining you can use a number of 8 sections as long as you tell the software how many Photo 2 The undisolved NaCl or KCI pellets that remain in the brine are too large to fit through the plastic egg crate This enables the e
233. verb When you tap the Scan Pots button briefly the next Set is loaded from memory 2 3 and 4 After Set 4 it wraps around and loads Set 1 again When the Scan Pots button is held the potentiometers are scanned and adjustments to the gains reverb delay pitch offset will be made accordingly If the Mode button is pressed while the Scan Pots button is being held the current readings from the poten tiometers are stored in the current set in flash memory If the most recently loaded set is 2 for example this over writes Set 2 It would say Writing 2 The next time Set 2 is retrieved it con tains these saved values FURTHER POSSIBILITIES This was all accomplished using a 28 pin package You might notice that this is not the largest package the Cypress CY8C29xxx family of PSoCs has to offer By upgrading to a 44 pin or even 100 pin PSoC all sorts of digital con trol and I O functions become possible For example while every analog block has been used there are still some unused digital blocks By simply cloning this project to a larger chip www circuitcellar com package a handy feature of PSoC Designer you gain the ability to add all sorts of communication schemes The PSoC has user modules for standard serial communications PC and SPI The pins may also be set up to bit bang custom or other communication schemes in or out of the chip The main loop still has some processing time left ove
234. y contamination or reaction from the ceramic magnets I dipped each into Plasti Dip a liquid plastic coating used on many tool han dles This turned out to be more diffi cult than I had anticipated because of the magnet s strong attraction to the 56 Issue 217 August 2008 Photo 1 You can see the foam float shaped inside the brine tank of our water sof tener system The domino sized magnet is glued along the right edge of the float The tank s interior 4 vertical pipe prevents the float from rotating out of alignment with the Hall sensor PCB mounted on the tank s exterior can s metal side I taped a thread to the magnet so I could immerse it and hang it to drain and dry The pull of these magnets simply ripped off the thread as it jumped to the can s side creating the mess I was trying to avoid I should have poured some of the liquid into a plastic cup first EGG CRATE AND FOAM On my last trip to the hardware store I seized the opportunity to search for the items I needed for this project In the insulation aisle I found some 1 high density foam This became my brine float This foam doesn t crumble like the block foam that comes as most packing material In the lighting aisle I found some 2 x 4 plastic egg crate grills for fluores cent fixtures They became my pellet float Using the plastic brine tank s lid as a pat tern I cut a disk out of the foam and the egg crate I also c

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