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1. 2 Mouser Electronics C2 NetBurner 3 Noritake Co Inc 37 Nurve Networks LLC 75 Ontrak Control Systems 77 PCBCore 17 PCB Pool C4 Parallax Inc 77 Phytec America LLC 74 Picofab Inc 78 Pioneer Hill Software 65 Pololu Corp 45 PROPOX Sp z o o Page Page Page 78 Pulsar Inc 41 48 Rabbit A Digi International Brand 76 Rabbit A Digi International Brand 76 Reach Technology Inc 76 Renesas Technology 49 RoboBusiness Expo 76 Saelig Co 12 Sealevel Systems 9 SEGGER Microcontroller Systems LLC 55 Sensors Expo amp Conf 74 TAL Technologies C3 Tech Tools 72 73 Technologic Systems 76 77 Technological Arts 76 Tern Inc 75 Trace Systems Inc 74 Triangle Research Int l Inc 68 Trinity College Robot Contest 74 Vantec Construct a USB GPIO Pod Part 1 No Parallel Port No Problem Robot Navigation and Control Part 2 Software Development Digital Decoding A Design for Decoding Periodic Signal Transmissions THE DARKER SIDE Time Domain Reflectometry Detect Measure and Locate Impedance ABOVE THE GROUND PLANE Solar Data Capture PCB Layout Woes Inductor Design and More FROM THE BENCH Programmable Robotics Part 2 Application Development SILICON UPDATE ZStar Trek A Healthy Mix of MCUs Sensors and Wireless Technology www circuitcellar com CIRCUIT CELLAR INDEX OF ADVERTISERS PREVIEWof April Issue 225 Th
2. rem Both of these routines use a conversion to decimal format on the 16 bit data in r1 and r0 DoDebug_SenDist jmp DoDebug_SenAng Ldi char2send D call byteTx ldi char2send call byteTx lds r1 SENSORS_OUT SenDist1 lds r0 SENSORS_OUT SenDist0 call SendDecimal DoDebug_SenAng jmp DoDebug_SenChargeState Ldi char2send A call byteTx ldi char2send call byteTx lds r1 SENSORS_OUT SenAng1 lds r0 SENSORS_OUT SenAng0 call SendDecimal DoDebug_SenChargeState 2903002 bachiochi qxp 2 5 2009 12 46 PM Page 61 62 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 continually add the sensor angle val ues to determine when you ve rotated the proper amount You must then use the drive command to halt the motors velocity 0 Distance works the same way While the value of every sensor available is not used in this program I ask for it all any way just as an exercise It also makes the next section more interesting as you will see shortly DEBUGGING You don t have a way of getting inside the microcontroller and single stepping execution or looking at reg ister values but you can get the next best thing The single UART in the ATmega168 is actually directed by external circuitry toward either the USB port for bootloading your pro gram or Create s serial port via the 25 pin expansion connector to respond to your program s
3. 2903003 cantrell qxp 2 5 2009 12 59 PM Page 64 www circuitcellar com CIRCUIT CELLAR 65 March 2009 Issue 224 all the way to the 1970s when Freescale then Motorola introduced their first micro the MC6800 The architecture of the MC6800 was blessedly simple com prising little more than two 8 bit regis ters A and B an index register X and the usual stack pointer SP program counter PC and condition code CC registers see Figure 1a Over the following decades i e 1980s and 1990s Motorola introduced a num ber of variations on the MC6800 theme Along the way there was a fork in the road with classic favorites like the MC68HC11 taking the high road and the down sized MC68HC05 taking the low While the MC68HC11 and MC68HC05 remain mainstays in the catalog the modern era roughly corre sponding to the Freescale spinout has been centered on the core known as the S08 What s remarkable after some 30 years is how true the S08 remains to the original see Figure 1b The menu has grown to include hundreds heck maybe thousands at this point of distinct par ts crafted from a few basic ingredients Given that history the new RS08 stands out by virtue of the fact that it s noticeably different something immedi ately apparent with a glance at the pro grammers model see Figure 1c The hardly symptomatic of a dead market Freescale Semiconductor is no excep tion They ve been o
4. The SPI master controls the WIZ810MJ Other than a handful of I O lines none of the microcon troller s other features are used Although it seems like a shame to use so few features it would be pointless to complicate the design The WIZ810MJ is a network mod ule that takes care of most of the complexity of adding TCP IP net working to a design In SPI mode only a handful of the 56 pins are needed The rest can be left as no connects The version of the module that I worked with has a known problem in that it continues to drive the SPI lines even when its SS is unasserted The work around is to drive the module pin SPI_EN low which will free up the other SPI lines The ATmega168 uses the SPI lines for serial programming so I had to do the SPI_EN trick even though there are no other SPI devices The WIZ810MJ draws a fair amount of current so I did not want to leave it powered up continuously I toyed with the idea of adding cir cuitry to power the module on and off Because the network link LED status is available on a module pin I could periodically power on the module check for an active link and turn it off In the end I just put in a toggle switch which was crude but effective A ULN2803 is used as the solenoid driver It is an eight driver package with internal clamping diodes The inputs are logic level and were connected directly to port pins on the micro controller Each driver can sink 500 mA which is
5. a serial cable to send individual commands 10 built in demos over 30 built in sensors and a 25 pin expansion port Programmable Robotics Part 1 Build on an Existing Robot Platform O by Jeff Bachiochi ccasionally I get dragged to the nearest mall especially around Christmas time Few of the stores interest me But Brookstone is different It is a nation wide specialty retailer with an assortment of con sumer products that are functional in purpose distinctive in quality and design and not widely available from other retailers Years ago I was drawn in by a Frisbee shaped gizmo wandering around on the floor near the store s entrance It was an iRobot Roomba vacuuming robot iRobot s literature described it as the first practical and affordable home robot You may have heard of iRo bot which developed robots like the PackBot that was used to search the rubble of the World Trade Center in New York after the September 11 terrorist attacks It is now used by the U S military overseas Apparently iRobot quickly sold more than 1 million Roomba units This success led to a line of similar robot ic appliances used for vacuuming sweeping washing floors and cleaning pools and gutters As you can imag ine when the robots started becoming popular hacking sites sprang up with information about ways to use these platforms for unintended purposes iRobot took advantage of this growing frenzy and developed an offshoot based o
6. right off a ledge thereby needlessly speed of 57 600 bps Commands include an opcode 128 159 followed by a number of data bytes depending on the opcode Table 1 lists the opcodes and data requirements of each I color coded the table so you can see the groups Five commands place the Create into special modes The Create begins in Off mode and remains there until a Start command is received The Start command places the Create into passive mode ready for additional commands From 2903002 bachiochi qxp 2 5 2009 12 46 PM Page 57 58 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 testing its poor aerodynamic charac teristics The built in demo programs can be called through the open interface using the commands in rows 6 8 and row 15 see Table 1 Note that while Cover Cover and Dock and Spot are available as individual commands the Demo command with a data byte of 0 9 lets you choose any of the built in demos For instance the Cover and Dock demo instructs the Create to use random bounce wall following and spiraling to cover a room s floor area If it sees an IR sig nal from its home base it will zero in on home base dock with it and recharge its batteries This brings us to the real nitty grit ty The commands in rows 2 9 14 16 22 and 26 29 have to do with the Create s I O The Create s outputs are left and right motors LEDs tone and output bits on the 25 pin
7. s an LCD marketing expert somewhere that has pronounced Segment LCDs are dead Yes it s true that bitmap graphics LCDs e g 1 4 VGA are all the rage and don t require any upfront NRE for custom glass a big advantage for low volume applications But don t think the success of bitmap displays sounds the death knell for segment LCDs They are still the best solution for high volume apps where requirements for low unit cost and long batter y life prevail And that s not to say segment LCDs can t do eye candy Witness some of the cool things being done in automotive dashboard displays includ ing free form i e nonrectangular panels Take a look around and you ll see segment LCDs are still a big deal Photo 3 The CodeWarrior RS08 toolchain that comes with the evaluation kit includes a full featured simulator that encompasses software hardware MCU pins and peripherals and even external I O devices like the LCD 2903003 cantrell qxp 2 5 2009 12 59 PM Page 69 70 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 It s all the more a bargain to get two evaluation kits for the price of one KEEP IT SIMPLER There is no doubt that some folks think all of this meat and potato tech nology is boring But not me I see the cost savings of these under a buck MCUs well under for the smallest parts passed on as a global Tech Tax cut for the masses I see the mil liamps across meg
8. Am I Sensors and Methods for Mobile Robot Positioning 1 and the SR04 robot by Photo 1 This is the entire navigation control subsystem as described in Figure 1 It is installed on the Rino robotic platform 2903015_ottaviani qxp 2 5 2009 1 18 PM Page 14 www circuitcellar com CIRCUIT CELLAR 15 March 2009 Issue 224 David Anderson 2 I was impressed by odometry and dead reckoning Most of the robots built by amateurs are based on a differential steering system a couple of driving wheels and a caster Knowing the space covered by each wheel periodi cally with enough precision enables you to calculate the position coordinates of the robot at any given moment As you can see in Photo 2 I tested different quadrature encoders Any dead reckoning navigation system is affected by cumulative error The measuring precision must be high to ensure a small error circle after a long path After some good results with homemade encoders I used something better a couple of 12 V 200 RPM geared motors connected to a couple of 300 count per revolution CPR quadrature encoders These parts are available at many online robotics shops I designed my simple robotic platform with easy to find components and parts that didn t require profession al tools or equipment or special skills I purposely devel oped a design that is properly sized for several different categories of robotics projects e g exploring robots line following
9. Current sensing ADC PWM QEI IC Motion controller 2 Motion feedback 5 V VREF LEDs Photo 4 These are the motors the encoders and the H bridges The metal box at the top contains a battery pack 9 V preregulators and PI filters It also acts as a heatsink 2903015_ottaviani qxp 2 5 2009 1 18 PM Page 16 www circuitcellar com CIRCUIT CELLAR 17 March 2009 Issue 224 much simpler There is no need for high speed commu nication between the super visor and motor controllers to exchange navigation parameters Every process is simple to synchronize because it s on the same chip The peripheral pin select capability of the dsPIC33F series further simplifies the PCB enabling an internal connection of peripherals and greater flexibility see Figure 2 For example the IC capture modules are internally connected to QEI pins saving two precious pins Moreover the COMM 1 port used for XBee connection can be software switched from UART to I2C or SPI commu nication with no hardware modifications Note that every one of the 28 pins is used on this board software When I started porting the software on a PIC18F2431 the hard ware QEI interface looked like the perfect solution The math capability of the dsPIC30F series arose as a use ful option for trigonometric calculi needed for odometry There are dual in line versions of this DSC and they are faster When the board and the programs wer
10. I O por t and configure the ViewPort interface Finally the Freq Synth call generates a 10 MHz clock to drive the ADC Photo 2 shows the oscilloscope with a timescale of 10 s division The wavefor m represents a horizontal trigger followed by a color burst and 50 s of data A pixel s brightness is proportional to the signal s value To complete your frame grabber object your algorithm must detect the horizontal and ver tical sync marks and then compress the pixel data into memor y Vertical and horizontal sync marks differ in the amount of time the sig nal stays at the lowest level After detecting a ver tical sync Photo 2 ViewPort shows raw NTSC signal from the camera as digitized by the ADC 2903017_Sander qxp 2 5 2009 1 11 PM Page 24 www circuitcellar com CIRCUIT CELLAR 25 March 2009 Issue 224 that you re working on 4 bit pixel val ues compressed into 32 bit longs A 32 bit long on the Propeller is the basic unit of memory space see Listing 3 This filter processes one pixel ever y five instructions Because the filter processes only data not sync marks or color bursts you can process video at 40 fps So the filter can easily keep up with the frame grabber object and update the position of the brightest spot in real time To integrate this code with the rest of your DanceBot simply keep this filter code running in its own cog The cog will continually filter the data provided by the frame grabber
11. Many flash memory MCUs feature in application programming capability that enables code updates in the field and also allows portions of the flash memory to be used as a psuedo EEP ROM for data storage By contrast it s important to note that the RS08 flash memory is really intended to be pro grammed just once as it goes out of your factory door There are a number of datasheet specs that make this conclusion obvious Unlike flash memory parts that can typ ically be written 10 000 or more times the RS08 flash memory write endurance spec is just 1 000 cycles In their frenzy to jettison ballast the RS08 designers also tossed the charge pump needed to generate the higher flash memory programming voltage 12 V so you re responsible for providing it exter nally And while the flash memory is organized and programmed on a 64 byte row basis there s only an all or nothing mass erase capability That means using the flash memory for multiple in appli cation writes would require a rolling update scheme that writes only once to a given location For example if you have 2 bytes of nonvolatile data you d like to update from time to time allo cating a 64 byte row of the flash memo ry would allow for 32 updates Nevertheless anything is possible and Freescale even has an application note describing such a pseudo EEP ROM scheme 1 It relies on moving a small flash programming routine from flash memo
12. Quartus II Web Edition design software package and the built in programmers you will be programming your own designs into the device quickly Power is provided either through the USB interface or with an external 9 V 2 5 mm adapter The development kit brings your I O pins out to headers and the voltage is selectable for 5 3 3 or 2 5 V logic levels The picoUSB comes complete with a user s manual reference design and exam ple HDL code The picoUSB starts at 145 per kit Volume and university pricing are also available Colorado Electronic Product Design Inc www cepd com Electrical engineers agree with a Protomat S Series prototyping machine at your side you ll arrive at the best solutions fast These highly accurate benchtop PCB milling machines eliminate bread boarding and allow you to create real repeatable test circuits including plated vias in minutes not days Declare your independence from board houses Affordable entry level price tag The best milling speed resolution and accuracy in the industry Single sided double sided and multilayered machining without hazardous chemicals Optional vacuum table and autosearch camera for layer alignment For complete details visit www lpkfusa com or call 1 800 345 LPKF ProtoMat S Series PCB Milling Machines NEW PRODUCT NEWS Edited by John Gorsky POCKET SIZED LINUX PC WITH GPS AND GPRS The AarLogic C10 3 is a breadboard t
13. command requests The control that does this switching is an output bit on the ATmega168 You have access to this which means from your program you can flip back and forth between desti nations Because the microcontroller is set up to go into bootload mode whenever a USB cable is plugged into the Command Module s USB port swapping destinations is impossible unless you know the secret Note that holding down the User button while resetting the microcontroller can deactivate this function For debugging purposes I can write a routine to send the sensor data out of the USB port each time the sensor data is copied into the working regis ters Note that even though you can check the UART to see if any charac ters remain in the transmitter you should add a delay of at least one character before switching the serial output destination to ensure that you are not interfering with a transmis sion in process To view the debugging data you can use a terminal emulator like RealTerm Because you are now anchored again with tether you will want to place the Create up on a sup port to keep its drive wheels off the ground You will also need to com ment out the safety checks within the program so the Do Movement loop isn t exited when one of the cliff sen sors is triggered I use conditional assembly with a Debug mode that eliminates certain code I started by just sending the data bytes as received While RealTerm enables you to
14. file has a FILE structure associated with it and probably buffers for data If you re building a simple system or just using the card for program updates then a fancy file system makes no sense On the other hand if you ve got one of the new ARM CPUs with an Ethernet interface built in all for about 5 and lots of system memory then you would want and could use a much more robust file system Let s explore the FAT file system in more detail as designed by Microsoft and extended by the card manufacturers and others The Wikipedia reference is a good con densed explanation of the different FAT versions The original FAT sometimes referred to as FAT12 is probably old enough that you don t need to support it The FAT16 ver sion supports volumes up to 2 GB and that s probably sufficient for today s designs But when will you no longer be able to purchase 2 GB CF cards When will the larger capacity cards be less expensive It probably won t happen next year but it probably will in the next four to five years So designing a system compatible with FAT16 has a shelf life and you better consider FAT32 as a real possibility Why not design or plan for both Another consideration is long file name support This is one decision that s clearly application dependent The systems I m working on can require all file names to be in the 8 3 format eight characters for the name and three for the extension And also an
15. for fol lowing community odd even watering restric tions The ITAP s internal data model consists of an array of program structures that keep all of the specifics for a program including start times and run length times for each zone All times are kept in minutes rather than hours and minutes Inter nally this simplifies storage and compar isons A running count is kept of the day of the year in addition to the day of the month The for mer is used for computing every N day cycles The latter is used for odd even days of the month SOFTWARE The software divides into micro controller support network code data model access file storage and timer logic The microcontroller support code is minimal The only interrupt is the Timer 2 overflow which is configured as a 4 Hz R TC Everything else is done by polled I O Every couple of seconds the main loop checks if the WIZ810MJ has been powered up A simple read of the last byte of the IP address is performed If the module is off the byte will read as 0xFF If the byte matches the expected value stored in EEPROM the WIZnet module is assumed to be present and it is reini tialized The ATmega168 s PORT D con nects pin for pin to the ULN2803 solenoid controller Thus pin zero of PORT D corresponds to solenoid zero pin one to solenoid one and so on At each program step there is the possibility that you might request all zones to switch on To Photo 4 The
16. full bridge speed con troller without too much effort I carved some custom heatsinks for the new International Rectifier IRFP048 MOSFETs from an old Pentium heatsink and added a cooling fan on the outside of the box to complete the new speed control system Three stacks of standard NiCd RC car packs power the robot The first supply is for the main drive motors It is a parallel stack of two 7 2 V packs Those enable the robot to r un for about 30 min at slow speeds before needing a charge The second supply is for the router and the PIC WIZnet electronics I didn t want the control electronics and motors to share the same battery packs for a reason I knew the motor batteries would most likely be the first to r un down and I still wanted control over the ser vos at all times If you ve ever had an RC car or plane run away because the servo power went dead before the drive power you know what I mean I also didn t want to worry about conducted EMI from the motors into the other power supplies The Netgear router requires 12 V and the rest of the con trol electronics need 5 VDC I used a stack of three 7 2 V NiCd packs in series with two LM350T regulator cir cuits to supply these voltages The addition of the webcam and two more servos was too much cur rent draw for the 5 V supply because the camera alone requires 2 A So I constructed an additional 5 V supply from two 9 6 V RC car NiCd packs and another LM350T
17. have gone too far The servo control pulse must also be eventually cause internal damage to the motor or gears so keep that in mind when writing RC servo code If Listing 4 This is the UDP packet format and transmit routine if UDPLinkActive True then begin UDPString 1 char 170 10101010 UDPString 2 char SteeringPercent UDPString 3 chr ThrottlePercent UDPString 4 chr PanPercent UDPString 5 chr TiltPercent UDPString 6 char 85 01010101 IdUDPClient1 Send UDPString end Listing 5 Receiving battery voltage telemetry from the robot if UDPLinkActive True then begin VBATT_Value IdUDPClient1 ReceiveString IdTimeoutDefault if VBATT_Value 1 V then begin Vbyte1 byte VBATT_Value 6 Vbyte2 byte VBATT_Value 7 VBATT_Number 3 3 Vbyte1 256 Vbyte2 1024 VBATT Text format 2 1f VDC VBATT_Number end end else VBATT Text No Data end 2903014_Coppersmith qxp 2 5 2009 4 32 PM Page 45 46 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 boxes and the status of the joystick switches are shown using checkbox es The mapping of joystick axis to the robot control servo variable is done with up down spin buttons and a case statement The UpdateCalibration proce dure takes this raw data and changes it into percentage values for the UDP client inverted if needed If the client is active it sends the data out over the network to the robot at
18. if necessary In this state you can r un it all while the wheel spins without floor contact pressing buttons and bumpers and watching for proper responses Of course you ll want to pull out the tether and try it on the floor even if it is misbehaving But use caution If you aren t paying attention to safety issues the Create may try to run over the cat if the bumper routine doesn t work Or it might continue backing up if you aren t paying attention to dis tance because there are no bumpers in the rear Now I need to think about what kind of external sensors I might want to add to support a mapping project This should be interesting ARE YOU CREATIVE If you want to check out some of the projects others are working on visit the Create projects link in the Resources section You will find a bevy of third party add ons that were devel oped for the Create Refer to http forums irobot com irobothome and www avrfreaks net for discus sions about iRobot and Atmel related things If you want to work with an afford able robotic platform without having to deal with building and testing hardware from scratch this is an ideal vehicle If you want to begin with a proven design and add your own sensors this is an ideal platfor m While the top of the line Create with more stuff than I ve discussed here costs 300 the basic unit begins at approximately 100 It can really help jump start your robotics research
19. jumpers Software controlled qty 1 449 Audio codec with speaker 200MHz ARM9 Touch Panel Computer 73 qxp 8 11 2008 2 12 PM Page 1 74 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 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 sh eet ALL TEXT AND OTHER ELEMENTS MUST FIT WITHIN A 2 x 3 FORMAT Call for current rate and deadline information E mail adcopy cir cuitcellar com with your file and digital submission or send it to IDEA BOX Cir cuit Cellar 4 Park Street V ernon 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 pr oducts and services I DEA BOX UUSSBB Add USB to your next project it s easier than you might think USB FIFO up to 8 mbps USB UART up to 3 mbps USB Microcontroller boards pre programmed with firmware 2 4GHz ZigBee amp 802 15 4 RFID Reader Writer Absolutely NO driver software development required www dlpdesign com ib 224 qxp 2 5 2009 11 38 AM Page 74 www circuitcellar com CIRCUIT CELLAR 75 March 2009 Issue 224 Tools for Embedded Development ARM7 MODULAR TOOLSET C C Code Wizards Debugging Simulation www crossware com info crossware com Advanced software tools sinc
20. memory to the network No compression code is needed The pages are just a payload Modern browsers already accept gzipped data so nothing additional is required Using JavaScript makes static con tent possible The JavaScript lan guage has constructs for dynamically building pretty much anything that can be done with HTML All of the ITAP tables and forms are dynami cally built The data needed to fill in the tables and forms is formatted using JavaScript Object Notation JSON and resides in a separately loadable JavaScript file The file is built on the fly each time a ser ver request is made for pdata js In a larger system data would likely be passed as XML XML is a bulky for mat intended for data exchange between unrelated systems XML really has no place in point to point micro applications The nice thing about using JSON is that it is auto matically parsed as it is read by the browser Additional parsing is not required Another important benefit associ ated with putting all of the UI build ing code in JavaScript is that there is a clean separation between the UI view and the data model The data model is maintained by the ITAP firmware The firmware knows nothing of UI layout A change to the UI does not require a fir mware change COMPRESSED FILES Looking through the WIZnet sam ple code I noticed copyright notices around the code that accesses flash memory based files Thus I thought it would be
21. oFrame 3010 to 0 with the operator we will have an eight pixel horizontal black line in the center of the image CON _clkmode xtal1 pll16x _xinfreq 5_000_000 OBJ vp Conduit transfers data to from PC video VideoCapture capture video signal pub findblob videoFrame 6000 a blob vp register video start videoFrame video HIVIDEO vp config string start video vp share blob blob repeat repeat videoFrame 3010 Photo 3 This is the system s first picture of a fire truck Notice the black line at the cross hairs 2903017_Sander qxp 2 5 2009 1 11 PM Page 26 www circuitcellar com CIRCUIT CELLAR 27 March 2009 Issue 224 understand how ViewPort vision filters work build a filter to look for transi tion edges in your video Looking at relative changes in value improves the robustness of your algorithm especial ly when lighting conditions change The horizontal Soebel filter is quick to implement and does a good job of detecting vertical edges To compute it replace each pixel with the absolute value of the difference of its horizontal neighbors Next you need to design a filter that will identify regions with multi ple strong transitions The algorithm I chose keeps a running total of the last eight edges by adding the strength of the next edge and subtracting the last This running total is saved to the appropri ate location in the buffer Your last filter finds the location of th
22. optimized middleware from the industry s largest ecosystem are setting the hardware and software standards for microcontrollers These standards enable leading vendors such as Luminary Micro NXP and STMicroelectronics to supply advanced microcontrollers while maximizing code reuse across multiple platforms Standards Make Sense STM32 microcontrollers revolutionize the market by combining high performance and low power with a scalable product range that fits every developer s needs Daniel Colonna Microcontrollers Division Marketing Director Cortex M3 Microcontrollers Make Sense For more information visit www onARM com The Architecture for the Digital World ARM Ltd AD158 2 01 09 Find us at Embedded Systems Conference San Jose March 30 April 3rd ARM Stand 1502 ST Stand 1412 2903017_Sander qxp 2 5 2009 1 11 PM Page 29 Jameco Electronics new catalog and enhanced Jameco com website are two tools that are designed to work together to give electronic professionals faster access to the hottest components in the industry Color coded references throughout the catalog assist you in analyzing a wide range of brand choices from franchise sourced to house brands to factory overruns offering you more pricing options than you ll see anywhere else Web codes allow you to quickly jump from catalog to website to view additional specifications application notes photos and more pro
23. product development or technical education Next month I will explain how to replace the Command Module with a microcontroller You are well on your way to developing your first application I 2903002 bachiochi qxp 2 5 2009 12 46 PM Page 63 8 bits is dead That s what a micro marketing expert told me What s funny is that he said that 30 years and an untold billions of 8 bit chips ago But hold on The stor y gets even better A few years later I bumped into this fellow again and learned he had moved on to a new job at a different chip company Things were going quite well and he was making lots of money selling 8 bit micros You ve heard me tell that story before and no doubt I will tell it again Yes 32 bit MCUs are on the march and growth is explosive And it s true there s an ever shifting gray area between high end 8 16 bit chips and low end 32 bit chips where it makes perfect sense for the latter to replace the former But the problem with the 8 bit eulogies is that they re based on the premise that silicon is a zero sum game If 32 bit MCUs go up that means 8 16 bit MCUs must go down right Zero sum may be the way it is for some businesses but not silicon As long as Moore for Less is the name of the game everybody wins And don t forget to look at the big picture How many 8 16 bit MCUs touch your life They re in virtually every electronic gadget Now consider developing s
24. see the data in various formats such as ASCII binary or HEX there are a few problems with this as you might expect Not all of the data makes sense in any one for mat And some sensor values are multibyte rep resentations of a word value It makes sense to format each sensor value appropriately and send the value as ASCII characters For bytes used as bit flags binary might be appropriate For signed word values a or sign would be appropriate and so on You can get as fancy as you wish A name or an alias that helps to identify it would also be useful You don t have to limit the data to just the Create s sensor values You can display any variables your pro gram is calculating Be careful what you choose to dis play Too much data can be just as bad as too little Your screen can fill quickly Logging to a file will be helpful in some instances The idea is to help you narrow down where to look for a bug in your code When the robot backs up and rotates forev er it might not be so obvious where to start looking in your code I filled my debug output routine with every possible piece of data to export I added a jmp instruction at the begin ning of each section of code for o ut putting that particular piece of data see Listing 1 I can quickly REM out the jmp instruction of any sections I want to include in the debug display Photo 2 shows power related data I monitored from the Create Note that the num b
25. sophis ticated vision guided balancing r obot that can interact with its environment Hanno shows you how to tackle this project with a Parallax Propeller a handy design kit and an inexpensive camera Vision Guided Robotics A Next Generation Balancing Robot I FEATURE ARTICLE by Hanno Sander t s time to build the next generation of robots W ith today s technology our robots should be tall enough to look us in the eye and interact with us through sight Two years ago I started experimenting with the latest microprocessor from Parallax a camera and a vision In this article I ll explain how to integrate vision technolo gy in a project As I describe the balancing robot design you see in Photo 1 I ll cover parallel processing visual debugging vision algorithms and robot control with computer vision PARALLAX PROPELLER I started my project after my dad gave me a Parallax Propeller for Christmas Par allax is best known for its Boe Bot robot and BASIC Stamps but its Propeller chip is quickly becoming popular with engi neers and hobbyists because of its power and simplicity Its eight identical proces sors cogs share common resources such as global memory and an I O port but each can run its own program It was per fect for my application because I needed to sample many different sensors at different rates perform intensive filter calculations Photo 1a This is the base of the DanceBot with
26. the designated IP address and port see Listing 3 and Listing 4 The UpdateTelemetry procedure checks for any data sent back from the robot currently just one battery voltage and refreshes the edit box for that value see Listing 5 Just as important as having an oscilloscope handy for diagnosing electrical hardware issues a good net work analyzer is a must for watching packet data Ethereal now called WireShark is a GNU open source protocol analyzer program that works great for watching every byte that slips into and out of your network ports The camera video is shown on a panel that pops up over the joystick settings panel when you press the Click for BotCam but ton at the top of the for m see Photo 4 A file open dialog box is used to pick the HTML file to use for the camera panel see Listing 6 The HTML file downloads and runs a JavaScript file from the camera that streams video at a maximum of 30 frames per second at a maximum size of 640 480 pixels The fun part is that I can are connected to the router using short Cat 5 cables The router is also used as the DNS server even though the camera could operate as its own Wi Fi server if needed The UDP datagram is arranged in the UDP Datagram doc file posted on the Cir cuit Cellar FTP site When the WIZnet board receives a UDP message the PIC24FJ64GA002 first checks byte 1 and byte 6 to deter mine if the packet is valid It then adjusts each servo pin tim
27. to ftp ftp circuitcellar com pub Circuit_Cellar 2009 224 ESOURCE Microchip Technology Inc PIC24 Family Reference Manual DS39704A 2006 OURCES IRFP048 MOSFETs International Rectifier www irf com WVC54GC Wireless Internet video camera Linksys www linksys com DM300027 Development board and PIC24FJ64GA002 microcontroller Microchip Technology Inc www microchip com WGR614 Wireless router Netgear www netgear com WIZ810MJ Network module WIZnet Inc http wiznet co kr en P R S March 2009 Issue 224 CIRCUIT CELLAR www circuitcellar com 48 Keep abreast of the latest news from your industry delivered free to your desktop Sign up today at www electronicstalk com With a library of more than 49 000 articles from more than 3 000 companies we are the number one destination for people making purchasing decisions Electronicstalk matching buyers with sellers www electronicstalk com 2903014_Coppersmith qxp 2 5 2009 4 32 PM Page 48 APRIL 15 16 2009 BOSTON MASSACHUSETTS HYNES CONVENTION CENTER Join the International Business Development Event for the Personal Service amp Mobile Robotics Industry For Information on Sponsorship and Exhibiting Opportunities contact Ellen Cotton at ecotton ehpub com or 508 663 1500 x240 JOIN THESE LEADING COMPANIES AT 2009 ROBOBUSINESS Silver Sponsors Media Co Sponsors Academic Sponsor Listing as of Jan 30 For a
28. you to watch how each filter manipu lates the video in real time Now that you close so it s commanded to drive backwards Translating this algorithm into code is simple just scale and off set the x y location of the spot to con trol the robot The complete control program for the robot is posted on the Circuit Cellar FTP site To illustrate the tracking ability of this filter I can use ViewPort to dis play the streamed video with a super imposed trail showing the position returned from the filter over the last minute Photo 4 shows the grayscale image as seen by the camera with a yellow trail showing the path the bright source took LINE FOLLOWING WITH A CAMERA You can control the behavior of the robot by shining a bright light at the camera This works in some environ ments where you can control the lighting and ensure that no other objects reflect or create light to the camera that s brighter than your flash light It s also an active method where you have to power the flashlight I ll now describe a filter that is less restrictive and uses a passive method to steer the robot Most line following robots use two phototransistors to stay on a line They re programmed to ensure that one detector is on the dark line while the other is on the lighter background More sophisticated robots use addi tional detectors to detect the robot s exact position on the line to look ahead or even to recognize junc
29. 0 930 4326 E mail sean circuitcellar com ADVERTISINGREPRESENTATIVE Shannon Barraclough Direct 860 872 3064 E mail shannon circuitcellar com ADVERTISINGCOORDINATOR Valerie Luster E mail val luster circuitcellar com 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 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 circuitcellar com NewProducts New Products Circuit Cellar 4 Park St Vernon CT 06066 E mail newproducts circuitcellar com AUTHORIZED REPRINTSINFORMATION 860 875 2199 E mail reprints circuitcellar com AUTHORS Authors e mail addresses when available are included at the end of each article CIRCUIT CELLAR 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 or
30. 2007 1 38 PM Page 1 Mar09_CC Robots indd 1 1 20 09 4 21 PM C4 qxp 1 28 2009 2 30 PM Page 1
31. 3014_Coppersmith qxp 2 5 2009 4 32 PM Page 46 41 qxp 1 7 2009 3 07 PM Page 1 let anyone on the Net log in and watch the video while the robot is r unning I just need to give a viewer the IP address and log in credentials I can also set the Wi Fi security to keep hackers out AM I DONE YET No way There s a never ending list of gadgets and features for a Future Bot Now that the robot has a camera it needs some sort of VoIP to commu nicate with the people it encounters during its travels Have I mentioned all of the control buttons that need to control something A high resolution approximately 8 megapixels still cam era could be useful for getting a good shot of something the Internet camera finds interesting Maybe I ll rent it out to the fire department for search and rescue operations in tiny crawl spaces It could putz up and down the beach with an attached metal detector and tiny treasure scoop I need a job at NASA so I can do this full time I hope you enjoyed reading about the PICBot Have fun building your own I know you want one I Scott Coppersmith rscopper aol com holds a BSEE from Michigan Technological Univer sity and is currently working as a senior engineer for Robert Bosch LLC He also teaches evening classes at Ivy Tech Community College in South Bend IN Scott s hobbies include Tesla coils fusors lasers embedded systems and Delphi programming ROJECT FILES To download code go
32. 36 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 limit current inrush problems the software sets the values bit by bit with a small delay in between In a similar software rather than hardware role the WIZ810MJ s reset line is controlled by a por t pin rather than RC logic In addition to par ts savings this allows for a full par t reset The network code is designed for the specific task of communicating with the one browser that it expects to find on a private network The main loop polls the WIZnet sockets for a page request Only HTTP GET requests are honored The request can be for either a file stored in the flash memory file system or for a data page built on the fly Changes to the data model are accomplished with arguments of the page request In a system where a browser request causes some action such as writing EEPROM or switching on a sprinkler minimize the chance that a user unintentionally repeats the action by clicking the REFRESH but ton The method used here is to clean up the location line by retur n ing a 307 REDIRECT result code With no arguments to the page request pressing REFRESH will sim ply reload the page with no addition al actions When using the WIZ810MJ as a web server there is a potential trap if the pages being served are com plex The W5100 can support a max imum of four simultaneous connec tions If the HTML page ren dered by the browser has more than fou
33. Cover and dock 143 PWM Low side drivers 144 Low side driver 2 duty cycle 0 128 Low side driver 1 duty cycle 0 128 Low side driver 0 duty cycle 0 128 Drive direct 145 Right wheel velocity Left wheel velocity 500 to 500 mm s 500 to 500 mm s Digital outputs 147 Output bits 0 7 Stream 148 Number of packets packet ID 1 Packet ID 2 etc 0 42 Query List 149 Packet ID 1 Packet ID 2 etc Pause Resume 0 42 Stream 150 Range 0 1 Send IR 151 Byte 0 255 Script 152 Script length 1 100 Command opcode 1 Command data byte 1 Command opcode 2 etc Play script 153 Show script 154 Wait time 155 Time 0 255 seconds 10 Wait distance 156 Distance 32 767 to 32 768 mm Wait angle 157 Angle 32 767 to 32 768 Wait event 158 Event ID 1 to 20 and 1 to 20 2903002 bachiochi qxp 2 5 2009 12 46 PM Page 60 www circuitcellar com CIRCUIT CELLAR 61 March 2009 Issue 224 system on your PC which enables you to develop programs in C using the provided programmer s notepad IDE editor GNU GCC compiler and AVRDude downloader After installing this software you can explore the three example programs on the CD The first example DRIVE shows how to make the Cre ate move around and react to an object when its bumper signals come in contact with it The second exam ple INPUT teaches you how to int
34. DC to AC 7 Seconds per cycle 8 Helical 11 Impedance Z 13 Live current 14 Identifies wires 17 106 Bq 19 Normal V 20 x y 71 March 2009 Issue 224 crossword2 qxp 2 5 2009 4 54 PM Page 71 3x faster and backward compatible with TS 72xx TS 7200 shown with optional A D converter Compact Flash and RS 485 Embedded Single Board Computers Most products stocked and available for next day shipping Engineers on Tech Support Design your solution with one of our engineers 480 837 5200 Custom configurations and designs w excellent pricing and turn around time Over 20 years in business Never discontinued a product Low Price Low Power High Reliability using Linux development tools options include onboard temperature sensor A D Converter 8 channel 12 bit Extended Temperature Battery Backed Real Time Clock USB Flash USB WiFi 8 boards over 2000 configurations 2 USB ports 10 100 Ethernet up to 2 DIO lines up to 55 Fanless no heat sink Flash up to 128MB onboard SDRAM up to 128MB Linux Real Time extension Debian COM ports up to 10 200 MHz ARM9 Power as low as 1 4 Watt Open Source Vision Programmable FPGAs High End Performance with Embedded Ruggedness 128MB DDR RAM Gigabit ethernet 2 host USB 2 0 480 Mbps 12K LUT programmable FPGA 512MB high speed 17MB sec onboard Flash Sleep mode uses 200 microamps 2 SD sockets Linux 2 6 and Debi
35. Donald E Stephens Convention Center Rosemont Illinois www sensorsexpo com This Year s Conference Program Covers 18 Tracks Sensor Interfaces amp Sensor Integration Sensor Systems Design RF Sensing Wireless Sensor Networks Energy Harvesting Energy Conservation Low Power Sensing Harsh Environments Position Sensing Fiber Optics Machine Health amp Predictive Maintenance Smart Materials Novel Approaches to Measurement amp Detection Environmental Monitoring Business Trends amp Issues Wireless Standards Location Aware Sensing Novel Approaches to Biodetection Don t Miss the Sensors Opening Keynote Cassini Five Years at Saturn Dr Kevin Grazier Investigation Scientist amp Science Planning Engineer Cassini Huygens Mission to Saturn amp Titan NASA s Jet Propulsion Laboratory JPL N e w A p p r o a c h e s N e w T e c h n o l o g i e s N e w A p p l i c a t i o n s N e w I d e a s Produced Official Silver Media by Publication Sponsor Sponsor Sensors09_CircuitCellarAd indd 1 1 20 2009 2 18 10 PM 55 qxp 1 23 2009 4 19 PM Page 1 56 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 If you want to work on a robot but don t have to time build one from scratch check out iRobot s Create The robot incorporates several customizable features including a com mand module for on board programming
36. IZ810MJ Both new modules have 2 54 mm headers I 2903018_Bereiter qxp 2 5 2009 1 11 PM Page 38 3 qxp 12 29 2008 11 48 AM Page 1 40 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 Scott used a microcontroller an embedded Ethernet board and a wireless router in an innovative control system for a compact mobile r obot The robot fea tures a mounted webcam that transmits r eal time pictures to a r emote laptop Scott explains how he planned the project assembled the pieces and cre ated the control software Wireless Mobile Robotics A Wi Fi Enabled System With a Mounted Webcam R FEATURE ARTICLE by Scott Coppersmith obots are everywhere They are used to build cars They are sent to poke at rocks on Mars Small rovers can vacuum your pool or your house and there are several different models at the local toy store I ve played with RC cars boats planes and helicopters for many years but after seeing TV shows like BattleBots and Junkyard Wars I had an itch to build something big ger and better to play with In 2001 I volunteered as a mentor for a FIRST Robotics Competition at Penn High School in Mishawaka IN It was an incredible experience If you like building mechan ical devices I recommend that you consider becoming a mentor The FIRST robots use controllers similar to stan dard RC types which are capable of telemetr y and feed back but they are a bit pricey for the average
37. Jeff Bachiochi pronounced BAH key AH key has been writing for Circuit Cellar since 1988 His background includes product design and manufacturing You can reach him at jeff bachiochi imaginethatnow com or at www imaginethatnow com ESOURCES iRobot Corp iRobot Create Open Interface Specification 2006 www irobot com filelibrary pdfs hrd create Create 20Open 20Interface_v2 pdf Command Module Owner s Manual 2007 www irobot com filelibrary pdfs hrd create Command 20Module 20Manual_v2 pdf Create projects http store irobot com family index jsp categoryId 2591511 amp ab CMS_IRBT_CreateSuperCat_LearnMore_110408 OURCES ATmega168 Microcontroller Atmel Corp www atmel com Create programmable robot iRobot www irobot com RealTerm Terminal emulation software RealTerm http realterm sourceforge net S stopwatch I even use it to lear n a rou tine I ve copied from somewhere else After assembling the code I use AVR Dude installed with the Create CD to download my HEX file to the Cre ate through the command module s USB port If I have the Create up on blocks I can execute from here by holding down the User button while pressing the Reset button This can be done when the Create is off because the Command Module has its own power switch When the Command Module begins execution it can check the status of the Create through the 25 pin expansion connector and turn it on
38. LJoyEx UpdateJoystick UpdateCalibration UpdateTelemetry end Listing 3 This code is for servo axis data calibration scaling and inversion if checkbox9 Checked True then SteeringPercent 100 trunc SteeringValue StMax StMin 100 else SteeringPercent trunc SteeringValue StMax StMin 100 2903014_Coppersmith qxp 2 5 2009 4 32 PM Page 44 www circuitcellar com CIRCUIT CELLAR 45 March 2009 Issue 224 repeated every 20 ms for the ser vo control IC to stay awake Controlling one servo is rather sim ple But when you have several ser vos the timer interrupts can conflict so it s best to have one timer inter rupt routine resetting all the others for the main 20 ms loop An oscilloscope can be handy for checking pulse widths and timing The PIC24FJ64GA002 has five internal 16 bit timers Section 14 of the document PIC24 Family Ref erence Manual shows all of the reg isters involved with the timers This microcontroller has programmable I O pins so you must also tell the device what pin is to be used as what func tion during code initialization The set up code for one of the ser vo con trol output pins and the associated timer registers is in Listing 1 WIZnet amp Wi Fi Controlling the PICBot is achieved by sending UDP packets back and forth from a remote laptop to a WGR614 wireless router The Linksys Internet camera and the WIZnet PCB the servo is humming but not mov ing you may
39. ROBOTICS Robot Navigation Control Subsystem Wi Fi Enabled Mobile Surveillance Vision Guided Balancing Robot Networked Timing System CIRCUIT CELLAR www circuitcellar com T H E M A G A Z I N E F O R C O M P U T E R A P P L I C AT I O N S 5 95 U S 6 95 Canada 224 March 2009 File Storage Tips p 51 Programmable Robotics p 56 The 8 Bits Story Revisited p 64 Cover 224 qxp 2 5 2009 9 14 AM Page 1 C2 qxp 1 29 2009 10 42 AM Page 1 9 qxp 8 7 2008 11 04 AM Page 1 www mouser com Over A Million Products Online The Newest Semiconductors Experience Mouser s time to market advantage with no minimums and same day shipping of the newest products from more than 366 leading suppliers 800 346 6873 The Newest Products For Your Newest Designs The ONLY New Catalog Every 90 Days Mouser_CircuitCellar_3 1 indd 1 1 20 09 5 00 23 PM 2 qxp 1 29 2009 10 48 AM Page 1 3 qxp 2 5 2009 9 30 AM Page 1 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 NEWPRODUCTSEDITOR 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 86
40. ST YOUR EQ 13 CROSSWORD 71 INDEX OF ADVERTISERS 79 225 Preview PRIORITY INTERRUPT 80 Cloud Computing Steve Ciarcia 51 LESSONS FROM THE TRENCHES FAT File System Review Part 1 Open Files and Perform Operations George Martin 56 FROM THE BENCH Programmable Robotics Part 1 Build on an Existing Robot Platform Jeff Bachiochi 64 SILICON UPDATE A Really Simple Plan The 8 Bits Saga Continues Tom Cantrell 224 14 Robot Navigation and Control Part 1 Construct a Navigation Control Subsystem Guido Ottaviani 22 Vision Guided Robotics A Next Generation Balancing Robot Hanno Sander 31 Networked Timing Build a Timer With Advanced Planning Tools Thomas Bereiter 41 Wireless Mobile Robotics A Wi Fi Enabled System With a Mounted Webcam Scott Coppersmith March 2009 Robotics p 22 Balancing Robot Design p 56 Work from the Inside Out p 14 Mobile Control TOC_224 qxp 2 5 2009 9 27 AM Page 6 2008 Atmel Corporation All rights reserved Atmel logo and Everywhere You Are are registered trademarks of Atmel Corporation or its subsidiaries Other terms and product names may be trademarks of others Everywhere You Are Performance and power consumption have always been key elements in the development of AVR microcontrollers Today s increasing use of battery and signal line powered applications makes power consumption criteria more important than ever To meet the tough requirements of modern mic
41. Station Plus or Modular Controller as a host device to display the text and graphics on the PFM Red Lion Controls s host devices and free Crimson software enable the PFM to receive message data from virtually any device on the factory floor supporting over 170 different protocols and the ability to send and receive data from seven or more device types simultaneously The PFM using a Red Lion host offers several additional fea tures for enhanced usability and unprecedented flexibility includ ing vibrant green yellow and red LEDs It has four sizes ranging from 26 6 6 at 80 16 resolution to 39 3 22 5 at 120 64 resolution and can send and receive data from seven or more device types simultaneously it also incorpo rates bar graphs custom symbols and other graphics to dis play production trends and goals It presents data from a sin gle device or uses custom calculations to display optimized production data from multiple devices They also feature an addressable RS 485 port to support multidrop wiring Please contact Red Lion Controls for pricing Red Lion Controls Inc www redlion net 802 11B G WLAN ACCESS POINT MODULE The WIZ610wi is an 802 11b g WLAN access point module in a pin head type package Serial to WLAN can be easily implemented with any system that has a UART interface With the WIZ610wi development time is reduced because WLAN driver porting is not required Also the module guarantees excellen
42. a CompactFlash http en wikipedia org wiki CompactFlash File Allocation Table http en wikipedia org wiki File_ Allocation_Table P R and build the information that you will use to access the card from the identity information Jeff described this process for an SD card In the files section of this article I took code from a 2005 Cir cuit Cellar article by Ivan Sham William Hue and Pete Rizun and passed it through SourcePublisher from Scientific Toolworks Portable FAT Library for MCU Applications Circuit Cellar 176 2005 I used this program to document my work and help organize other C code I includ ed the original files and the output from SourcePublisher Together with these links and Jeff s most recent columns you now have an introduc tion to a file system But wait There s more Next time I ll get into the hear t of some C code for a file system I March 2009 Issue 224 CIRCUIT CELLAR www circuitcellar com 54 2903013 martin qxp 2 5 2009 1 19 PM Page 54 A d v a n c e s i n M e a s u r e m e n t M o n i t o r i n g D e t e c t i o n amp C o n t r o l Register Today for Your Conference Pass at the Early Bird Rates Or Sign Up Now for a FREE Expo Hall Pass Visit www sensorsexpo com or call 877 232 0132 or 972 620 3036 Outside U S Don t Forget to Use Your Source Code 303M Conference June 8 June 10 2009 Exhibits June 9 June 10 2009
43. a sizes the design point that the net work connection is only there for reprogramming the device Fancy reports and real time status pages are engaging for the first few weeks of ownership but then for most peo ple the excitement of watching the grass grow begins to fade The long periods of time between reprogramming make it so you don t have to install any information on a PC It is usually not a problem to pop in an installation CD when you first buy a product Assuming there are no missing drivers or system conflicts the first install is easy The problem comes six months later after you have upgraded your PC and cannot find the installation CD For the same reason it is important that all HTML pages live on the device Photo 2 The irrigation schedule is the main browser page Four solenoid valves are represented by zones a d The three different programs determine at which time and on which days the zones will be active Listing 1 This shell script compresses the HTML and JavaScript files as part of building the firmware image The compressed files reside in the Atmel ATmega168 s flash memory bin sh FILES error html index html edit html common js cal html day html for f in FILES do id echo f tr _ echo prog_uchar id gzip 9 v f xxd i echo done gt gz_data inc SCK1 __builtin_write_OSCCONL OSCCON 0x40 lock 2903018_Bereiter qxp 2 5 2009 1 11 PM Page 35
44. a relationship of the distances trav eled by each wheel The distance between wheels is 260 mm If only one wheel is moving that wheel must travel 2 R or 1 634 mm i e 2 260 mm to get back to where it started so 1 634 360 4 5 mm degree Figure 1 This is the idle flowchart I wrote by reviewing the code in the example DRIVE C on the CD that came with the Create Initialization Clear LEDS_COUNT Update sensor info LEDS_COUNT gt 100 Alternate LED pattern Play start song Y Y Y N N N LEDS_COUNT LEDS_COUNT 1 User button pushed Update sensor info Update sensor info Play stop song Stop motors Do movement User button pushed or other safety error 2903002 bachiochi qxp 2 5 2009 12 46 PM Page 58 www circuitcellar com CIRCUIT CELLAR 59 March 2009 Issue 224 type in commands in decimal with spaces separating input values The Create will execute the commands in the order they are received If you type 128 132 139 2 0 0 lt cr gt you will turn on the Play gt LED If you enter a drive command support the system underneath with its wheels off the floor full mode The Create will most likely rip your serial cable out as it bolts across the floor unless you have a long tether I know what you are thinking Not user friendly this tether Well there is of course a better way You can eliminate the tether by supplying an RF link I wan
45. ample for a typical irriga tion solenoid valve drawing about 200 mA at 12 VDC The solenoids are 24 VAC but are quite content run ning on 12 VDC Conve niently inputs and outputs and not on a PC If the device requires a PC installation it stops being a stand alone device and becomes yet another peripheral ready to break when you modify your PC HARDWARE The hardware was designed to include the fewest number of par ts The essential parts are an Atmel ATmega168 a WIZ810MJ network module and a ULN2803 Darlington array see Figure 2 I do all of my development work in Linux The excellent AVR toolchain available for Linux is one of the reasons I prefer Atmel microcontrollers With Linux command line tools I can do all of my firmware development at my desk not hunched over the lab bench An old laptop sits on the lab bench and serves as a network to USB gateway for the in circuit programmer I chose from a standard web browser The browser pages provide data entry and display capabilities of the watering schedule as well as calendar based planning tools The entire design is self contained There are no extra files scripts or drivers that need to be installed on a PC An irrigation timer is not some thing you reprogram often After an initial period of fine tuning the unit is expected to work unattended for the rest of the season I did not need to add any daily reporting only a minimal status page This emph
46. an by default 10 serial ports qty 100 229 Unbrickable design 5 ADC 10 bit 2 SATA ports 110 GPIO Boots Linux in lt 2 seconds Internal PCI Bus PC 104 connector shown w optional SD Cards TS 7800 500 MHz ARM9 Low power 4W 5V qty 1 269 qty 100 99 qty 1 129 as low as SD card option VGA video LCD ready 72 qxp 8 11 2008 2 02 PM Page 1 Systems Technologic Visit our TS 7800 powered website at We use our stuff www embeddedARM com TS ADC16 ADC DAC and Digital I O Up to 100Ksps 10us Prog pacing clock 1KB ADC RAM FIFO TS RELAY8 see our website for more boards and option details Featured Products and PC 104 Peripherals qty 1 169 16 16 bit ADCs 4 ADC voltage ranges qty 1 89 TS TPC 7390 64MB SDRAM 128MB opt Dedicated framebuffer 8MB RAM 800x480 customizable video core Programmable FPGA 5K LUT 512MB Flash w Debian Linux Runs Eclipse IDE out of the box Boots Linux 2 6 in about 1 second Unbrickable boots from SD or NAND Runs X Windows GUI applications 7 Color TFT LCD Touch Screen Mountable aluminum frame Low Power Industrial Quality Design Eight Software Controlled Relays see our website for x86 SBCs peripherals and option details 4 inputs 1 output 4 16 bit counters 4 12 bit DACs Externally triggered Up to 277 VAC 5A Up to 30 VDC 5A 8 SPDT relays 40mA draw per coil I O
47. and write the x y location of the brightest spot into the main memory You now have two channels of information updated at 30 times sec ond with which you can drive the two control channels of your robot speed and direction Use the x position of the spot to control the tur ning rate of the robot If the spot is in the middle you don t need to do anything How ever if it s on the left side of the image the algorithm tells the robot to turn left until the spot is in the cen ter and the robot is facing the source of the spot A similar technique con trols the robot s speed using the verti cal position of the spot The algo rithm s goal is to keep the spot s posi tion centered in the image So when the spot is too low the robot is instructed to move forward which brings the robot closer to the spot s source Because your camera is look ing up at the spot it will raise the spot in the image Conversely if the spot is too high your robot is too mark the code initializes a new frame and processes one video line at a time For each line it detects the horizontal sync skips past the color burst and then samples the ADC s value every five instructions for a line length of 240 pixels To fit a complete video frame into the Propeller s global mem ory I store 4 bits of brightness infor mation for each pixel This data is accessible by all eight cogs on the Pro peller In the DanceBot one cog is dedica
48. and colors of each column cor respond to a zone from the main schedule page For simplicity the height of the bar is limited to one of four discrete steps The bar graph is not a GIF or JPEG image Instead it is implemented in JavaScript as a four row table with variable ROWS PAN elements As with the rest of the UI the firmware reports only the data The JavaScript makes all display and layout decisions The final page is the Day page which drills down from a calendar bar chart to show when during the day the water will run see Photo 5 Each tick mark corresponds to a 15 min interval The tick marks are constructed from TABLE rows with a small white border to highlight the individual tick Together the Day and Calendar pages make for accu rate what if planning I did not originally plan to have sta tus view or zone on off over ride but tons because I did not expect to have the network connected except during reprogramming I later added these features mainly for debugging and March 2009 Issue 224 CIRCUIT CELLAR www circuitcellar com 38 Editor s note This project won First Place in the 2007 WIZnet iEther net Design contest For more information about this design and the other winning projects go to www circuitcellar com wiznet Thomas Bereiter itimer micaview com has written software for ever ything from microcontrollers to huge distributed systems He has a B S in computer science from the Un
49. and solenoids The BL4S100 and BL4S200 development kits are available that include the essential hard ware and software tools The BL4S100 kits cost 199 The BL4S200 kits cost 299 The BL4S100 SBCs are available in 500 plus quantities starting at 98 The BL4S200 SBCs are available in 500 plus quantities starting at 176 Rabbit Semiconductor Inc www rabbit com npn224 qxp 2 5 2009 3 29 PM Page 10 www circuitcellar com CIRCUIT CELLAR 11 March 2009 Issue 224 NPN EMBEDDED LAN MODULE Nano LANReach is an embedded LAN module that quickly and easily connects any embedded device to 10 100BaseT LANs with minimal programming Based on the CO2144 chip Nano LANReach offers plug and play serial to LAN func tionality enabling immediate and full featured LAN connectiv ity by connecting an Ethernet cable to the onboard RJ 45 connector In addition the module includes a full suite of Internet protocols applications and security engines Nano LANReach s firmware supports two modes of opera tion The first is serial to LAN bridge mode which enables transparent bridging of serial data over a LAN using the module s high speed UART The module supports TCP UDP or SSL tunneling of serial data The second is full Internet controller mode which enables simple microcontrollers to use the module s rich protocol and application capabilities to perform complex Internet operations such as e mail FTP SSL embedded web ser
50. arator VDD ADC In 47 nF C 4 k7 R 2903003 cantrell qxp 2 5 2009 12 59 PM Page 68 www circuitcellar com CIRCUIT CELLAR 69 March 2009 Issue 224 configure the processor s own clock module to generate a periodic e g 1 ms wake up call Let s not overlook the small matter of debug The RS08 background debug mode BDM provides the basic com mands e g read write registers and memory breakpoints single step to get a handle on things It s like a sim ple ROM monitor but it is less intr u sive e g memory can be accessed without stopping the user program and consumes no resources e g flash memory or RAM beyond the single pin BKGD used for host communica tion and flash memory programming MARKET SEGMENT With the MC9RS08KA1 and MC9RS08KA2 staking their claim at the entry level Freescale recently announced two high integration RS08s the LE4 and the LA8 In terms of the processor core itself everything you ve read so far applies except there s more memory 4 or 8 KB of flash memory and 256 bytes of RAM and larger 28 and 48 pin packages The real difference and reason for the extra pins is a significant boost in the on chip I O capability with MCU mainstays such as UART SPI fancier timers and a multichannel 10 bit ADC The final I O add on and raison d etre for the L parts is a built in seg ment LCD controller Now I m quite sure there
51. at Embedded Systems Conference San Jose March 30 April 3rd ARM Stand 1502 Luminary 1802 2903017_Sander qxp 2 5 2009 1 11 PM Page 25 26 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 look around and imagine what type of pattern would stand out in our typical cluttered world For most people a bar code like pattern of repeated black and white lines should do relatively well Of course this pattern won t suit everyone e g Zebra lovers may need to find another pattern But this pat tern doesn t occur often and it can be identified reasonably easily with a chain of simple vision filters Before you analyze the individual fil ters analyze how ViewPort manages a chain of vision filters Because the Pro peller s memory is a limited resource you can afford only to keep one image in memory at a time To visualize the effects of different filters segment the image array into four vision buffers top left top right bottom left and bottom right Both the frame grabber and vision objects support both the full size and the segmented modes Filters operate on buffers in that they read data from one place and write their result to another The DanceBot uses one cog to continuously process image data with a number of filters one at a time Configuring the filter s order param eters and values is high level Spin language Streaming all four vision buffers to ViewPort enables
52. aunits power sav ings as a green tsunami sweeping away a zillion batteries that would otherwise consume resources only to end up in a landfill Dare I say I think this stuff is sexy and sure to spawn innovative applications I applaud Freescale and for that matter all the other MCU suppliers hopping on the keep it real bandwagon for standing up to the experts and naysayers who are enamored only with prima donna technology My only advice to Freescale and the others is remember to keep it simple And then remember you re supposed to remember to keep it sim ple There are already plenty of fea ture creeped 8 bit MCUs to choose from Don t get me wrong the high er end parts are wonderful too and I m not necessarily against reinvent ing the wheel But like putting fat tires and tail fins on a go kar t tarting up a mini me MCU isn t the way to do it I apologize to readers who ve had to sit through my 8 Bit Lives stor y before And let me apologize in advance because it s a story I suspect I ll be telling again and again I in applications such as appliances thermostats calculators glucose meters not so smart phones and hand held test equipment e g digital VOM The list goes on And just as with 8 bit MCUs in general if seg ment LCDs are dead why is it that heavyweights like Freescale and all of the other major players Atmel Microchip Technology Texas Instru ments and more keep int
53. ays of connecting to a browser but they invariably required some type of installation on a host PC Around that time I saw the WIZnet iEther net Design contest 2007 announcement and decided to build my timer design around the WIZnet WIZ810MJ network module A potential design trap in a network enabled device is the temptation to do too much with the network An irrigation timer should be a simple device It is after all just a timer and some solenoid valves The network interface is present in the design because it is the best way to connect to a web browser I have always been drawn to simple low cost designs so I used the network interface to save money by eliminating an LCD and key board Others might use the network inter face as an excuse to jam in seldom used features and boost the end product s price Once I started building a web browser interface I realized that this was a good oppor tunity to show that web technologies which are nor mally associ ated with large enterprise deployments can also be used effectively on micro devices ITAP DESIGN The design philosophy was to not consider the IT AP as a networked or web enabled device but rather to use the Figure 1 This shows the interaction between the browser pages the hardware and the physical zone valves Hardware model and control Low voltage wiring Valve manifold Browser view Network What if calendar report Schedule and zone tab
54. bit direct addressing modes that work with certain instruc tions Carefully craft your data layout to put the most frequently accessed data in the TINY space first 16 bytes Mean while the most frequently used I O and now rather tired RISC versus CISC debate it s pretty clear that the RS08 is still a CISC because instructions can operate directly on memory It s just a Complex Instruction Set Computer that happens to have a Reduced Instruction Set Given what you ve seen so far it is no surprise that entire categories of traditional i e S08 instructions such as those having to do with SP and X are vaporized Fur ther even the instructions that remain have fewer variants e g no 16 bit direct address mode only zero offset indexing We re not talking about a minor weight loss Considering both the number of basic instructions as well as all possible opcodes i e combinations of instruc tion and addressing mode the RS08 instruction repertoire is slashed to well under half the S08 According to Freescale the RS08 core is fully 30 smaller than the S08 INTERRUPTS DISABLED As you might expect the absence of a real i e hardware stack poses a chal lenge for dealing with interrupts The RS08 has a straightforward approach to the problem If interrupts are a hassle ditch them altogether You heard me Table 1 Thanks to new SHORT and TINY addressing modes the l
55. calendar view shows what will happen this month The bars in the bar graph correspond to the zones The height of the bar shows the relative time that the zone will be on that day Photo 3 The program details on the main page are read only Clicking edit brings up an editable version 2903018_Bereiter qxp 2 5 2009 1 11 PM Page 36 www circuitcellar com CIRCUIT CELLAR 37 March 2009 Issue 224 subelements Newer chips such as the WIZnet W5300 support up to eight sockets An early design trade off in a proj ect like this is deciding how much flash memory to devote to storing HTML page data It would have been easier in many ways to just wire in a 1 GB SD flash memory card and fill it with the output from a web site builder tool However this would have negated the strong desire I had to show by example that an attrac tive useful and feature complete UI could be implemented on a small footprint device Accepting the limitations of finite storage the question was how to stay as small as possible Early in the design process I considered keeping HTML templates in some sort of compressed form The plan was to decompress the templates fill in the actual values and then serve this modified data to the browser The final design is better in ever y way If the pages are not modified but instead have static content they can be highly precompressed with the gzip utility and simply copied unmodified from flash
56. ctorW UINT16 dest UINT32 LBALocation void WriteCF_SectorB UINT8 dest UINT32 LBALocation void WriteCF_SectorW UINT16 dest UINT32 LBALocation void ReadIdentityInfoW UINT16 buff void ReadIdentityInfoB UINT16 buff UINT16 CFByteSwap UINT16 data UINT8 Get8Bits UINT8 Buffer UINT16 addr UINT16 Get16Bits UINT8 Buffer UINT16 addr UINT32 Get32Bits UINT8 Buffer UINT16 addr 2903013 martin qxp 2 5 2009 1 19 PM Page 53 SD MMC card format be compatible with another computer system A straightforward example is that the card be readable and writable in your embedded system and in a PC Then the questions become Which OS is the PC running Does that OS sup port the same file system as your embedded system does If you are going to read and write memor y cards only in your system compati bility with an existing OS in not an issue WORKING WITH THE SYSTEM So how does one work with the FAT file system I urge you to search the Net and get as much infor ma tion as you can stand And there is a lot available You ll find that you need to detect and initialize the card read the identity infor mation a roll our own project But I came to my senses and decided this was too big a project to tackle There are so many CF cards and I should also deal with SD and MMC cards Also each application has its own resources and requirements One such requirement is how many files can be open Each open
57. current list of Sponsors amp Exhibiting Companies visit www robobusiness com USE PRIORITY CODE RBCC SAVE 300 REGISTER NOW ON YOUR FULL CONFERENCE PASS BUILDING THE ROBOTICS INDUSTRY Now in its sixth year RoboBusiness Conference amp Exposition is the must attend event for those involved in the business and technical issues related to the development of the personal service and mobile robotics industry The emphasis of RoboBusiness is on what technologies and applications are emerging with the greatest opportunity to be commercially successful FOR COMPLETE EVENT DETAILS VISIT WWW ROBOBUSINESS COM OR CALL 800 305 0634 RoboBusiness is a professional trade event All attendees must be at least 18 years old to attend www robobusiness com WORLD CLASS CONFERENCE RoboBusiness 2009 features two days of keynotes and general sessions delivered by internationally recognized leaders from business government and academia RoboBusiness conference tracks EXPOSITION amp SPECIAL EVENTS around the world Produced By Founding Sponsor Premier Sponsor Association Sponsors 49 qxp 2 5 2009 4 57 PM Page 1 63 qxp 1 7 2009 3 20 PM Page 1 www circuitcellar com CIRCUIT CELLAR 51 March 2009 Issue 224 If you are designing a system with a removable memory device try using a file storage system such as the FAT file sys tem George describes how to open files with the system use a CompactFlas
58. d Refer to the Resources at the end of the article for information about the file systems If you purchase a CF or SD MMC By now you should be starting to understand what these prototypes mean The new construct in all of these prototypes is the FILE fp It is a pointer to a str ucture that can be seen in Listing 3 Every time you open a file using C you are creating a str ucture and filling in the details The str ucture is all that is needed to per form all the file operations that the C language has to offer This is a simple straightforward interface and you should be suspicious that it s too easy I suspect that there is a lot of code to support the simplicity of this interface For example buffer is a pointer to a character buffer What s up with that Where is that buffer stored and how big is it A useful assignment that would give you a lot of insight into this problem is to find and review the Linux file I O code OPEN A FILE Let s examine how to open a file The fopen procedure takes two parameters The first is the complete file name including the path So E Data CCI Code Test TestFile txt is a string that can be used as a com plete reference to the file Note that it s a string and you pass a pointer to that string If you are r unning C on a PC the OS takes care of translating that path and file name into a specif ic hardware location If you re designing an embedded system you re respons
59. d examine the lowest level interface to the hardware It s the only other piece of information that s solid at this point Again using the Inter net I came up with several links to CompactFlash information CompactFlash There are several ways to design a hardware interface around a CF card One simple method has eight registers using three address lines that provide commands data and status informa tion Also either an 8 or 16 bit data interface is available The hardware interfacing to an SD MMC card basi cally uses the serial peripheral inter face SPI format I have not yet done this type of design work so I ll say no more at this point about SD MMC card interfacing Again refer to Jeff s articles for details about an SD hardware interface The lowest level of CompactFlash hardware and software interface can be accomplished in the routines in Listing 4 The Init_CF routine grounds the RESET pin on the Com pactFlash card Note that not all cards respond correctly or complete ly to this reset Some require that power actually be removed Some designs have a high side FET actual ly disconnecting the power supply So look out The next four routines CFCheck_ RDY Wait_RDY CFCheck_RDY_ ALT and Wait_RDY_ALT look at a ready or alter nate ready signal from the CF card This signal is the reply that indicates that the CF card has completed the previous opera tion Sometimes you just want to lo
60. d it s emulated using a pair of memory locations X and D X in the TINY address space 2903003 cantrell qxp 2 5 2009 12 59 PM Page 65 control registers including the afore mentioned PAGESEL register are mapped into the remaining SHORT space bytes 17 32 In return for taking full advantage of the scheme you get the speed and code density advantages of single byte instructions see Table 1 SP is gone and as you might imagine so is the stack Instead there s just a Shadow PC register SPC that acts as a single level stack for interrupts and subroutine calls In a pinch e g you need nested subroutine calls instruc tions to move data between the accumu lator and the high and low bytes of SPC give you hooks to mimic a hardware stack i e PUSH and POP macros Without getting sidetracked by the 66 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 MC6800 and its descendants were lean and mean but the RS08 is positively anorexic You ve all seen the movie Back to the Future right Well the RS08 is kind of a Forward to the Past scenario with Freescale introducing a core today that s architecturally simpler than the circa 1970s original After a glance at the programmers model the first question that arises is how in the heck can the RS08 get any thing done Yeah there s an accumula tor A but just how are you supposed to get data into or out of it with t
61. d by your frame grabber on the PC CON _clkmode xtal1 pll16x _xinfreq 5_000_000 OBJ vp Conduit transfers data to from PC qs QuickSample samples INA up to 80Mhz Freq Synth pub demoADC a frame 1600 6 frame stores 1600 samples configuration vp register qs sampleINA frame 1 vp config string var io adc decode io 0 7 vp config string dso view adc trigger adc lt 15 timescale 50us vp share 0 0 Freq Synth A 8 10_000_000 repeat Standards improve quality and enable designers to share components across different projects Today ARM Cortex M profile processors combined with the Cortex Microcontroller Software Interface Standard CMSIS and optimized middleware from the industry s largest ecosystem are setting the hardware and software standards for microcontrollers These standards enable leading vendors such as Luminary Micro NXP and STMicroelectronics to supply advanced microcontrollers while maximizing code reuse across multiple platforms Standards Make Sense We based our award winning Stellaris microcontrollers on Cortex M3 to provide users with 32 bit performance while eliminating future architectural upgrades or software tool changes Jean Anne Booth Chief Marketing Officer Luminary Micro Cortex M3 Microcontrollers Make Sense For more information visit www onARM com The Architecture for the Digital World ARM Ltd AD158 2 01 09 Find us
62. ders payable in U S funds only via Visa MasterCard international 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 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 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 is for educational purposes Circuit Cellar 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 reader s jurisdiction The reader assumes any risk of infringement liability for constructing or operating such devices Entire contents copyright 2009 by Circuit Ce
63. design and out to successful manufacture gt Easy connection to company wide systems 2903015_ottaviani qxp 2 9 2009 9 50 AM Page 19 20 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 There are four PID algorithms in this software that control the navi gation Two for speed of the wheels one for orientation and one to control the distance from the target The four PIDs are independent so they can be set up separately First of all you can take care of the speed PID of one motor controller changing the Kp Ki and Kd values in sequence until the motor runs smoothly responding quickly to the commands and without overshoot The other motor will probably run fine with the same constants After the speed can be regulated accurately the right K values for angle PID first and dis tance PID later can be found with the same logic The axle size and wheel diameter can be measured on the robot with a caliper but they must be fine tuned to make the vehicle go straight turning the right angle and r unning the right distance You can achieve the first tuning by comparing the RTC COMPETITION As design engineers we all need a goal By goal I mean a target that justifies the amount of time we spend debugging and tr y ing to make our circuits work like they did in the simulations In an effort to get more people interested in the goal of building robots a bunch of us members of the Roboteck Inte
64. designer These days however you can pick up a W i Fi router for approximately 30 and a used laptop for as little as 100 The two of these along with a fast Microchip Technology PIC micro controller and a WIZnet embedded Ethernet board make a nice plat form for a robot project In this article I will describe how I built a robotics system which I call the WiFi PIC Bot along with the control software and inter face electronics see Photo 1 I entered this project in the WIZnet iEthernet Design Contest 2007 Photo 1 This is the assembled WiFi PIC Bot with a webcam Pan and tilt servos are located just below the camera But since then the robot has gone through a few upgrades You can view the project as it was then www circuitcellar com wiznet winners DE 001106 html The WiFi PIC Bot is a modified RC ClodBuster dual motor four wheel drive with four wheel steering monster truck I replaced the RC ser vo receiver with a WIZnet WIZ810MJ embedded Ethernet board controlled by a Microchip Technology PIC24FJ64GA002 The WIZnet board is connected to a Netgear WGR614 wireless router that transfers steering and throttle ser vo data as UDP pack ets back and forth to a remote lap top The PC program reads a joy stick sends the servo commands out through its Wi Fi card and dis plays a real time picture from a Linksys WVC54GC Internet ready webcam mounted on the robot One of the latest upgrades was pan and tilt s
65. ducts You ll find exactly what you re looking for without having to wade through hundreds of thousands of products on a complicated website or wielding a twenty pound catalog With a flip of the page or a click of the mouse you have all the tools you need at your fingertips Reach for Jameco first and order your catalog today Experience a Faster Way to Search for Components Call 1 800 831 4242 or Visit www Jameco com Speed for the ride of your life Order your web enabled catalog today Jameco_CC_Dec08 10 8 08 8 37 AM Page 1 41 qxp 10 27 2008 11 11 AM Page 1 www circuitcellar com CIRCUIT CELLAR 31 March 2009 Issue 224 Precision irrigation control is now a reality Thomas s irrigation timer with advanced planning ITAP is a truly novel irrigation con trol system The easy to use system which directs user interaction into a standar d web browser pr ovides useful information such as watering schedules and zone activity Networked Timing Build a Timer With Advanced Planning Tools E FEATURE ARTICLE by Thomas Bereiter lectronics are supposed to simplify our lives but all too often the reverse is tr ue While research ing irrigation timers I was struck by how the evolution from an electromechanical design to an electronic design had actually made the device less usable Early irrigation timers were based on the simple rotar y motor design still popular in plug in appliance timers A geared mot
66. e ib 224 qxp 2 5 2009 11 39 AM Page 77 78 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 ib 224 qxp 2 5 2009 11 39 AM Page 78 75 AAG Electronica LLC 32 AP Circuits 75 All Electronics Corp 19 Altium Ltd 76 Apex Embedded Systems 25 27 ARM 29 ARM 7 Atmel 33 CWAV 57 CadSoft Computer Inc 34 Calao Systems 63 Comfile Technology Inc 75 Crossware Products Inc 75 Custom Computer Services Inc 74 DLP Design 69 DesignNotes 11 EMAC Inc 42 ESC West 77 Earth Computer Technologies 48 Electronicstalk 24 Elprotronic The Index of Advertisers with links to their web sites is located at www circuitcellar com under the current issue Page 20 ExpressPCB 10 ezPCB 74 FDI Future Designs Inc 78 FlexiPanel Ltd 11 Front Panel Express LLC 28 General Circuits 13 Grid Connect Inc 39 HI TECH Software LLC 69 HobbyLab LLC 47 50 ICbank Inc 77 IMAGEcraft 1 Imagineering Inc 78 Ironwood Electronics 32 34 JKmicrosystems Inc 75 JKmicrosystems Inc 30 Jameco 37 Jeffrey Kerr LLC 58 Keil Software 8 LPFK Laser amp Electronics 37 Lakeview Research 77 Lawicel AB 13 76 Lemos International 78 LinkSprite Technologies Inc 24 Linx Technologies 5 Luminary Micro 77 MCC Micro Computer Control 45 MachinePIER 77 Maxbotix 78 microEngineering Labs Inc
67. e interrupts per se the KBI s most likely use is to catch edges ris ing falling either and otherwise serve as a means to wake up the processor from a low power state Similarly there s an analog compara tor using up to three pins that can compare two external voltages to each other or to an internal reference volt age You can choose to trigger on the rising falling or either edge of a com parator transition and the comparator output can be routed to a pin Freescale application note 3266 describes how to use the comparator to implement a poor man s ADC using the familiar R C charge timing scheme see Figure 4 2 The ADC emulation also uses the final piece of the I O pie the MTIM timer module It s a simple unit with an 8 bit prescaler 1 2 4 256 divide ratio fronting an 8 bit counter Vari ous internal clock sources can be selected as the counter input or a pin can be devoted to the cause Note that the MTIM module is not capable of waking up the processor from low power mode Fortunately you can Photo 2 Freescale s introduction of the RS08 L series and the evaluation kit that goes with it proves that blue collar technology i e 8 bit MCUs and segment LCDs lives on Figure 4 The MC9RS08KA analog comparator can mimic a conventional ADC Software discharges the RC and then the MTIM timer measures how long it takes to recharge to the level of the psuedo ADC input On chip comp
68. e maximum in the buffer you just calcu lated You can use the same algorithm that you developed to track a bright spot By chain ing these three filters together you find the location of the maxi mum running total of vertical transitions In other words you can Photo 4 The DanceBot is tracking the path of a flashlight in real time Listing 3 This Propeller assembly function finds the brightest pixel in the video frame Thirty two bits of data are read using the rdlong command This represents eight pixels which are inspected one by one by rotating the bits with the ror instruction The location of the brightest pixel is written to the address pointed to by cmdPtr doMax 2 ptrs src dnp 2 value old dn setup ptrs to positions rdlong val cmdPtr add cmdPtr 4 mov dnp src add dnp bytesNline sub n 15 mov dest 0 seexy mov sum 0 max value loop rdlong old src add src 4 rdlong dn dnp add dnp 4 mov m 8 mov new 0 input old dn have pixel in 0 3 new has data output old dn rol by 4 dodiffb mov tmp old and tmp 15 tmp pixelvalue in mid mov t1 dn and t1 15 t1 pixel down add tmp t1 tmp two rows cmp tmp sum wc c if tmp lt sum if_c jmp notMax mov dest m shl dest 8 mov dest sum shl dest 16 add dest n mov sum tmp reset max notMax ror dn 4 ror old 4 djnz m dodiffb djnz n loop wrlong dest val jmp cmdLoop Standards improve quality and enable de
69. e 1984 Add support for Atmel NXP or STMicro ARM7 variants to Base Package to suit your requirements and budget ib 224 qxp 2 5 2009 11 39 AM Page 75 76 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 Starting at 125 Program in Assembler BASIC C and Forth www TechnologicalArts com Adapt9S12XDP512 Modular Prototyping System Robotics and Mechatronics Electronic Fuel Injection Freescale 9S12XDP512 RTOS capable Evaluate Educate Embed Wireless Analog 4 channel analog input wireless module 433 868 915MHz Low power serial interface Easy to configure 24 bit ID to avoid cross talk 2 digital output Unique stamp sized v low power multipoint an dig input 400 928MHz Tx Rx module Transmits to 50 feet Ideal for toys loggers mobile eqt 24 bit security Networkable for relative position tracking EmbedRF Module 59 EmbedRF DevKit 299 1 888 7SAELIG info saelig com www saelig com ib 224 qxp 2 5 2009 11 39 AM Page 76 www circuitcellar com CIRCUIT CELLAR 77 March 2009 Issue 224 Get started for as little as 29 SCI SPI Vreg 3 3V to 5V HCS12 CPU Key Wakeup Ports Background Debug CAN 2 0 A B 32K Flash 2K RAM 8 ch 10 bit A to D 16 bit Timer up to 6 channels PWM PWM PWM PW Program in Assembler BASIC C and Forth www NanoCore12 com Mechatronics and Robotics Advanced 16 bit MCU RTOS capabl
70. e access to the debug port on the ATmega168 used in the Command Module I m sure they wouldn t want the user to accidental ly wipeout the bootloader I couldn t use this tool Using the C code as a guide I went through the DRIVE example and came up with a flowchart Figure 1 shows the initialization and idle loop waiting for a User button push The movement routine in Figure 2 then takes over until a second push or any safety issues such as a cliff sensor are detected Items in round bubbles are calls made to other routines These can easily become a librar y of calls used over and over by your pro grams just like a library in C A couple of the routines are wor th mentioning When a bumper is detected a turn is requested with the direction based on the bumper so Create turns away from the collision My random angle routine uses the 7 least significant bits of the Timer1 register counter which increments rapidly with no prescaler The con stant 53 is added to this value 0 127 to allow angles between 53 and 180 or 53 and 180 degrees when rotating clockwise A drive com mand is then issued using a velocity of 200 mm s with either radius of 0xFFFFmm for clockwise rotation or 0x0001mm for counterclockwise rotation The random angle value becomes the requested angle and is compared to the angle returned by Create to determine when the turn is completed The update routine requests a full comple
71. e almost completed Microchip brought out a new powerful 28 pin SPDIP in the dsPIC33F series for both motor controller MC and gen eral purpose GP versions They are significantly faster than the dsPIC30F they have a lot more available pro gram memory and RAM useful for field mapping they require less power good for a battery operated robot and their DMA capabilities simplify many I O operations Most importantly these are the first Microchip motor controllers with two QEIs on the same chip Let s start a new port again The logical block diagram is simi lar to Figure 1 for the previous board but the hardware and software are Figure 2 This is the new board featuring the Microchip Technology dsPIC33F Internet pioneers with 15 years experience Instant online Quotations amp Ordering From Singlesided to 6 layers ML Leadtimes from 48 hrs Full DRC included on all orders High Quality prototypes at LOW cost s Simply send your layout files and order online www pcb pool com TollFree USA 1877 3908541 Email sales pcb pool com Specializing in Quickturn Proto s 2903015_ottaviani qxp 2 5 2009 1 18 PM Page 17 18 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 Serial communication is a good way to connect a wireless system Two serial ports on the DSC and a simple protocol such as the one I will describe later can be used Using a couple of XBee modules in transparent mode s
72. e hundred new desktops for its staff but it is certainly a bummer if you live in Redmond WA and work for a company trying to think up new ways of peddling more copies of Microsoft Vista and Microsoft Office grin Good or bad acceptance and extensive utilization of cloud computing in our future is as inevitable as multicore processors because the more computer applications we exercise and the more social connectivity we enjoy the more everyone wants I don t see myself starting a MySpace page and Twittering readers between bites at lunch but I do see the merits in being able to try many more software applications simply because using a virtual mainframe eliminates all the crash and burn terror of physically adding new software to an otherwise stable PC The caution is that cloud computing is still a cute and cuddly concept in its infancy but it can be easily monopolized or corrupt ed if we don t look at history when guiding the future Fanatical acceptance and hasty growth of cloud computing is being driven by an abundance of free and low cost applications that in my opinion are all about market share Beware that we may be trading one land based monopoly for new monopolies in the cloud based on computing power and services think Amazon and Google I ll be back Cloud Computing steve ciarcia circuitcellar com by Steve Ciarcia Founder and Editorial Director INTERRUPT Steve_224_Edit_Ver1 qxp 2 5 2009 1 38 PM Page 96 C3 qxp 3 30
73. echanical switch operated by a small ser vo Slow speed was accomplished by switching a resistor in series with the motors Each of these issues had to be addressed separately The first parts to go were the wimpy plastic body the RC receiver the mechanical speed control and the stock batter y packs An aluminum 8 12 2 5 box fit nicely on top of the frame It had enough room inside for most of the elec tronics and batteries I mounted power supply and speed control cooling fans power LEDs and switches to the out side of the box I drilled for ser vo wire access a program ming connector and network cable ports I added a multi terminal high amperage connector for on system batter y charging with bank selection I attached the Inter net cam era with its pan and tilt ser vos along with the Wi Fi router to the top of the box Both stock drive motors were already changed to high performance models so I left them as they were I changed the transmission gears to the highest gear ratio I could find to slow down the robot for indoor use and to add torque for moving the extra weight around I added hard r ubber sup ports inside the springs to the suspen sion system shocks to accommodate the added weight of all the batteries and new electronics The main motor drive speed control had an interesting set of issues to resolve Two parallel high performance motors operating at high torque require a high current controller with
74. eme Embedded Programming May Issue 226 Deadlines Space Close Mar 13 Material Close Mar 20 Theme Measurement amp Sensors Bonus Distribution Sensors Expo ATTENTION ADVERTISERS Call Shannon Barraclough now to reserve your space 860 875 2199 e mail shannon circuitcellar com 79 March 2009 Issue 224 79 advertiser s index qxp 2 10 2009 10 44 AM Page 79 80 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 PRIORITY You know a lot of what people are describing today as the future of the Internet sounds like d j vu to me Way back when I remember having dumb terminals all over the place that time shared the services of a remote located mainframe computer I loaded my data into programs that were batch processed on the central computer and then sent back to the terminals While highly effec tive when it came to getting more computing power than a slide ruler it was terribly ineffective when it came to time management data privacy and asset control It s no wonder why we all zealously jumped on the distributed processing bandwagon of personal com puting At least then we were in complete control limited only by how much processing power we could jam in the box on our own desk I call that progress Unfortunately technology has now progressed to the point where we seem to be heading in reverse again By whatever lack of historical perspective people are thinking that big service compan
75. er of variables you choose to display total characters sent will impact the execution loop speed of the program In AVR Studio I created a project with three files The first file m168def inc is the register bit defini tions file for the ATmega168 The second file CreateCmdDef inc is used to hold the definitions for all of the items directly relating to the Cre ate I also placed the callable routines I made to support the Create s com mands and my Debug code This kept the ugliness out of the main file The last file iRobotCreateTest1 asm is the main file This is the control pro gram It is the only file that must be written for a new project Assuming all of the commands have working code in CreateCmdDef inc the main code has includes that link the first two files One of the nice things about using AVR Studio is that it contains a simula tor I often use the simulator to calcu late routine timing using the integrated Photo 2 RealTerm is displaying some of the internal register values that have to do with power OC 0 no over currents CS 0 not charging V 14 973 battery 14 973 V mA 1 231 batteries supplying 1 231 A BT 18 battery temperature 18 C CRG 2 698 2 698 A h remain CAP 272 battery capacity is down by 0 272 A and CA 00000000 no source 2903002 bachiochi qxp 2 5 2009 12 46 PM Page 62 www circuitcellar com CIRCUIT CELLAR 63 March 2009 Issue 224 R
76. er value cor responding to the associated PWM channel The steering and throttle timer values give the correct range of servo movement span from 1 472 to 4 672 0x05C0 to 0x1240 hex for a total of 3 200 counts So the equation for the steering servo timer value is percent 32 zero offset and the equivalent PIC24FJ64GA002 code would be OC1RS Rx_Buffer 1 32 0x05C0 PC SOFTWARE The UDP client software for the laptop control is written in Borland Delphi Pascal The code uses the Microsoft multimedia library rou tines in Mmsystem dll to poll the joystick driver for available joysticks and their parameter tables I have col lected several joysticks over the years and all of them worked for the robot until I added the camera pan and tilt servos Not all joysticks have four axis controls however the con troller for my RealFlight simulator has five axes and several switch es with a convenient USB con nector I ve found that the older analog joysticks were a bit noisy for robot control and it s just about impossible to find a laptop with an analog game port on it these days I haven t used any of the joystick switches to control anything yet but I can imagine the next robot upgrade will have something to do with lasers or maybe some bottle rocket launchers or Nerf guns safer for work Once a joystick is selected from the main set up form the controls for various servos are mapped to the output cha
77. eract with the Create s I O and the Command Module s extra I O The third example LIGHT introduces you to the process of adding exter nal sensors In this example an added CDS light sensor to the command module is monitored while the Cre ate wanders the area When a signifi cant increase in light is detected the Create stops and plays a song This might be where we par t com pany As you probably know I like getting down and dirty so I m going to finish up this column by dis cussing using assembly language with the Command Module which I couldn t find much about on any of the Create related sites or forums I visited Although I think you get a great little development system here for the Create with the Command Module there is a missing piece that is important to me when I develop something debugging A debugging connector could have been added to the Command Module which would have made in circuit debugging sim ple There are a few mentions of how to use the USB port for feedback but there is conflicting information and there aren t any examples I m going to show you how to do this Although I ll be working in assem bler this can be done in C as well AVR Studio I ve used AVR Studio IDE in the past for development work with Atmel parts It includes a simulator which I use from time to time to check routines and other tools for debugging i e in circuit emulation Because I didn t hav
78. erial communica tion can be made wireless w ithout the need for any other protocol or special configuration On the dsPIC side just RX and TX pins are needed An affordable adapter is available to The number of components and connections is dramatically reduced On a board that is the same size as the previous one there is enough room for a second GP series DSC that will manage all of the robot s sensors Photo 5 shows the develop ment board used for porting At the end of the sof tware porting process I confirmed my first impres sion one dsPIC33FJ64MC302 is pow erful enough to manage all of the navigation tasks I had to take care just for the high rate of the input capture interrupts But with the tim ing chosen for the different PIDs the program spends more than 80 of its time idling in the main loop I ll cover this in more detail in the sec ond part of this article series TELEMETRY Any kind of closed loop control i e PID or other requires a fine setup to achieve its purpose If you really want to ask Where am I any parameter of the program must be fine tuned Several groups of parameters must be tested before finding the right sequence Believe me the most boring method is to change values in code recompile and burn the flash memory of the dsPIC over and over with the hex file You absolutely need an I O sys tem to read and write numbers to and from the program It s common to install a sim
79. ervos for the Linksys camera MODIFICATIONS Making an RC monster truck into a robot isn t a simple task Each issue had to be addressed sep arately Many of the original design components had to be modified to Photo 2 In the control box battery packs are at the top power supplies are at the bottom left and speed control is in the mid dle left A Microchip DM300027 development board with a WIZ net WIZ810MJ Ethernet board is in the lower right 2903014_Coppersmith qxp 2 5 2009 4 32 PM Page 40 Wi Fi and Ethernet Versions 42 qxp 12 27 2008 11 55 AM Page 1 Register Today embedded com esc sv ESC is the expo and conference for embedded design Check it out Tear it down Put it back together Keep it real Learn today Design tomorrow Do the Tear Down See our experts take apart the latest products and systems 69 qxp 1 9 2009 1 37 PM Page 1 www circuitcellar com CIRCUIT CELLAR 43 March 2009 Issue 224 make the toy into a reliable and sturdy robot platfor m The ClodBuster s single 7 2 V battery wasn t sufficient to run the vehicle for more than a few minutes and I couldn t use it for running the new processor adding servos the webcam and the wireless router The stock body and suspension system couldn t carry much weight The original motor gears were fine for zipping around the yard but were a bit too fast for indoor use The stock motor control was just a four position m
80. esn t hurt that most of these applications are free but at this point in its evolution I wonder how many of these free services are really virtual heroin The other side of the equation is that putting all your computing capability in assorted boxes is complex and expensive When we only had a single desktop it was less complex because we needed only a single software license for the operating system and pro grams we used As we progressed to having a couple of desktops and two or more laptops per house last count I had six total the issue became the inordinate cost involved with all the single platform licenses software updates and communication services need ed to support the farm Enriching Microsoft at every turn isn t a crowd pleaser any more than my having to buy six copies of the same virus protection software every year The attractiveness of the uncorrupted cloud concept is that people can supposedly use lower function computers i e cheaper with perhaps an open sourced OS and no single license indigenous applications Instead each box would simply connect to web sites in the cloud think virtual mainframes and execute subscription or pay by use application software as needed Instead of purchas ing schematic design programs or Microsoft PowerPoint for each computer companies simply sign on to application resources and do everything online for pennies This is nirvana for a medium sized outfit facing the purchase of a coupl
81. evelopment kit for explor ing ATmega AVR processors The XGS PIC 16 Bit is based on Microchip Technolo gy s new 16 bit PIC24 processor Both kits are designed to be serious develop ment kits for schools students engineers and anyone interested in learning pro gramming The XGS kits give designers a fun way to learn AVR and PIC programming in the context of graphics audio and simple game development So instead of blinking LEDs and displaying digits on a seven segment display designers will develop graphics applications that control the VGA and NTSC screen to learn C and ASM Each kit comes with a 350 plus page printed manual covering hardware soft ware and numerous programming tutorials a programmer and USB cable a 9 V power supply an A V cable a game con troller and a PC serial port to XGS header converter Also included is a DVD with numerous examples and a complete driv er library including graphics sound key board SD card serial communications mechatronics and more Bonus materi als on the DVD include electronic copies of numerous game development and electronics gaming hardware books The XGS AVR 8 Bit costs 139 99 and the XGS PIC 16 Bit costs 159 99 Nurve Networks www xgamestation com npn224 qxp 2 5 2009 3 29 PM Page 9 The BL4S100 and BL4S200 are SBCs that feature either Wi Fi or ZigBee connectivity a microprocessor memory and abundant I O that enable easy deployment of wireless nodes for industr
82. expansion connector 6 bits three digital and three PWM On the input side there are wheel drop sensors bumpers wall sensors cliff sensors virtual wall IR sensors overcurrent sen sors for wheel and PWMs buttons distance angle charging state bat tery voltage system cur rent battery temperature battery charge battery capacity and inputs from the 25 pin expansion con nector four digital bits and one 10 bit analog input You can refer to the Open Interface Specifica tion in the Resources section for more informa tion on all of this but I want to touch on it briefly There are two ways to move the Create The drive command requires 2 data bytes a velocity of 500 mm s and a radius of 2 000 mm That s a maxi mum speed of approximately 1 MPH This mode is similar to driving a car using the gas pedal for speed control and the steering wheel for direction control The drive direct command requires 2 data bytes a right velocity of 500 mm s and a left velocity of 500 mm s This mode is similar to driving a bulldozer or tank using independent forward and reverse levers for each wheel Feedback on movement comes from the wheel encoders as values for dis tance 32 768 mm to 32 767 mm and angle 32 768 to 32 767 The dis tance is the total distance covered by each wheel s encoder divided by two If the Create is spinning in place its distance remains at zero The angle is
83. few years ago he dusted off his scope and soldering iron and started making autonomous robots Guido is currently an active member in a few Italian robotics groups where he shares his experi ences with other electronics addicts and evangelizes amateur robotics position displayed on console with the position really measured on field A more accurate method is UMBmark which was developed at the University of Michigan 4 UP AND RUNNING The robotic platform is considered up and running when the motors are spinning the wheels the H bridge is driving the motors the board that controls the H bridge is functioning in the dsPIC30F or dsPIC33F ver sions and the communication sys tem needed for remote management is complete When the system is ready and you have a goal e g the RTC Competition you can start working But wait What else do you need The software Next month I will describe the soft ware you need on the board to navi gate the robot I will cover how to control the speed with PID closed loop control You will also learn how to use the encoder information to determine the robot s position with dead reckon ing by odometry Be prepared for some math Lastly I ll cover the over all software architecture that glues all of the pieces together I 2903015_ottaviani qxp 2 5 2009 1 18 PM Page 21 22 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 Are you interested in building a
84. g with a pigtail thermistor board for measuring temperature in remote locations The new sensing kit is easy to use right out of the box You can use the Sense and Control Dashboard software included in the new FirstTouch Starter Kit to quickly set up and monitor a wired or wireless sensor network through the intuitive visual dashboard The combination of the Environmental Sensing Kit and the dash board enable data logging data aggregation alarms and sensor calibration for nearly any type of sensor In addition the kit supports custom expansion for designers who want to develop their own applications The new CyFi Low Power RF solution delivers the industry s leading combination of reliable connectivity power efficiency and superior range It is supported by the flexible and easy to use PSoC programmable system on chip The PSoC reduces the complexity of quantifying a sensor s signal by integrating the amplification filtering and ADC stages into a single device Additionally the PSoC s analog MUX allows multiple sensors to be connected concurrently The CY3271 EXP1 Environmental Sensing Kit costs 99 99 and the CY3271 PSoC FirstTouch Starter Kit costs 69 95 Cypress Semiconductor Corp www cypress com S AVR AND PIC DEVELOPMENT KITS The XGS AVR 8 bit and XGS PIC 16 bit are new development kits that make learning and development easy The XGS AVR 8 bit is based on the Atmel ATmega644 AVR processor and is a highly integrated d
85. h card and per form other basic operations FAT File System Review Part 1 Open Files and Perform Operations F by George Martin or the past two years we ve been exploring the C language and specifically how to use it in embedded systems I ve introduced you to the language and described how to use it to construct typical systems I ve also described how to include more aspects of a design such as flowcharts UML diagrams and other development tools Well it s time to move on from the lower level details of the language and move up a level or two although from time to time I ll revisit the basics Feel free to e mail me if you have questions about embedded C systems FAT FILE SYSTEM If you re planning an embedded system it s probably not going to be a simple design with just a push button as an input and an LED as an out put In today s environment it s going to be rather complicated and full of features How in the heck do you design such a system I will answer that question indirectly because I don t believe there is a simple single answer There are families of answers or approaches to the design My goal is to present you with several alternatives Your goal is to under stand each one and decide how they might best fit your application LESSONS FROM THE TRENCHES Listing 1 Basic C file operations FILE fopen const char path const char mode int fclose FILE fp int fgetc FILE fp
86. hat contains a complete Linux PC on a surface of just 104 mm 63 mm A quad band GPRS module and a SiRF3 GPS module are also on board as well as interfaces for USB RS 232 and Ethernet components An SD card read er enables the trouble free expansion of the 4 Mb of RAM that comes standard The heart of the PC is two ARM processors that are responsible on one hand for the GSM component and on the other for appli cations executable under Embedded Linux The processor module including the GSM component is also available for purchase separately Despite its small surface area roughly the size of a matchbox its 192 pin socket provides a wide array of connectivity options Aside from keyboards digital cam eras and reading devices this also includes WLAN Bluetooth and GPS components The AarLogic C10 3 costs approximately 590 Round Solutions www roundsolutions com npn224 qxp 2 5 2009 3 29 PM Page 8 www circuitcellar com CIRCUIT CELLAR 9 March 2009 Issue 224 NPN WIRELESS ENVIRONMENTAL SENSING KIT The CY3271 EXP1 Environmental Sensing Kit is the first of many future expan sion offerings for the recently introduced PSoC First Touch Starter Kit with CyFi Low Power RF The Environmental Sensing Kit includes two boards a weather sta tion expansion board which includes sensors for atmospheric pressure humidity temperature and ambient light all of which can be operated and monitored simul taneously alon
87. hat accommodate con nection with different flavors of glass e g 3 V 5 V ST and STN Another nice touch is a blink attribute that handles that annoying chore e g the blinking colon on a digital clock without bothering the processor Freescale makes kicking the tires easy for you and your budget with the MC9RS08LE and MC9RS08LA evalua tion kits that are a real bargain see Photo 2 For just 59 you get a board with an LCD plus the usual trimmings buttons LEDs a buzzer and more And the boards have the USB debugger interface built in so you don t need a separate pod The kits also come with the venerable CodeWarrior suite and because the code size restriction for the evaluation version is 32 KB i e larger than the flash memory on any RS08 you re essentially getting a proven and production worthy RS08 toolchain for free Just before going to print one of the MC9RS08LA kits appeared on my doorstep I didn t have time to do more than install the tools fire it up and poke around a bit Once I jumped through the obligatory install hoops install CodeWarrior install the serv ice pack install USB drivers down load the demo project from the web and configure CodeWarrior project options everything I tried compile download debug and more worked without a hitch One feature that stood out was that the toolchain has a simulator that goes beyond just opcodes to include full chip i e pi
88. he disap pearance of the index X register The answer is a combination of direct addressing i e memory address includ ed in the instruction paging and an X index register in drag Here s how it works The entire address space for the RS08 is 16 KB comprising 256 pages of 64 bytes see Figure 2 But the direct addressing range tops out at just 256 bytes i e 8 bit address and the only instructions that can specify a longer address i e the full 14 bits are JMP and JSR To provide data access to the entire 16 KB the top 64 bytes of the direct address space i e page 3 direct addresses C0 FF are used as a window to any other page as specified with a page select PAGESEL register Index register X didn t really disap pear it just morphed into a memor y mapped emulation As you can see in Figure 3 location 000F doubles as the X register 8 bits as in the MC68HC05 and location 000E in turn acts as a holder for the data addressed Indeed this scheme can partially emulate MC68HC05 indexed addressing albeit more slowly to the point that the assembler accepts some traditional X register mnemonics as psuedoinstruc tions and automatically converts them to RS08 equivalents i e access via locations 000E and 000F Now let s focus a little on the R as in reduced aspects of the RS08 While the maximum direct address is 8 bits there are new SHORT 5 bit and TINY 4
89. ial commercial and medical applications This unique combination of control I O and connectivity makes it easy for engineers to add wireless connectivity and control to devices like vision systems wireless industrial control systems printing systems auto matic meter reading devices industrial ventilation sys tems and HVAC systems They also enable design engineers to easily gather and control data from ZigBee nodes and uplink the data to a server via Eth ernet providing an easy to deploy ZigBee to Ethernet gateway The BL4S100 series offers both ZigBee and Ether net connectivity and provides embedded design engineers a simple and straight forward approach for machine con trol and data acquisition without 10 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 NEW FAMILY OF WIRELESS SINGLE BOARD COMPUTERS NPN the burden of cables and wiring harnesses It enables design engineers to deploy ZigBee nodes at various control points and connect the nodes wirelessly to the BL4S100 board The BL4S100 SBC can then gather and collate the data from the ZigBee nodes and uplink it to a server via Eth ernet The high performance BL4S200 series delivers higher clock speeds and twice the I O as the BL4S100 series and offers a choice of Wi Fi or ZigBee connectivity It is ideal for applications that require significant digital and analog I O such as data logging instrument reading and controlling motors relays
90. ible for that transla tion The second parameter is the mode that you are using to open the file Different modes are r read w write and a append With these and other characters you can specify operations such as append start from the beginning and open for both reading and writing The return parameter from the fopen procedure is a pointer to the FILE data structure If the pointer is NULL a C defined constant the Listing 2 Alternative C file operations char fgets char string int length FILE fp int fputs const char string FILE fp Listing 3 Pointers pointing to 8 bit data in 16 bit elements typedef struct int level fill empty level of buffer unsigned flags File status flags char fd File descriptor unsigned char hold Ungetc char if no buffer int bsize Buffer size unsigned char buffer Data transfer buffer unsigned char curp Current active pointer unsigned istemp Temporary file indicator short token Used for validity checking FILE 2903013 martin qxp 2 5 2009 1 19 PM Page 52 www circuitcellar com CIRCUIT CELLAR 53 March 2009 Issue 224 command failed to open the file Aren t you glad you read and paid close attention to my articles on structures and pointers Refer to Circuit Cellar issues 198 200 202 204 206 208 210 212 and 214 I am going to skip over the middle of the FAT file system design an
91. ies shared software applications and remote computing are bet ter than local services and local control This isn t a rant Personally I see benefits and detriments on both sides of the argument Specifically I m talking about cloud computing and its ramifications While some use this term to describe virtual client servers on the Internet I prefer the more accepted description that cloud computing is all the real time software and subscription based serv ices that you use via the Internet This includes things like Google Docs virtual data storage video viewing posting services Google Maps etc etc It s a long list and the cloud gets bigger every day I attribute the move toward cloud computing as an addictive escalation in all the connectivity that everyone seems to be seeking It s not enough to just have a cell phone number where we can be reached any more Now we have to have constant live downloads to steroid stuffed communication devices designed to enhance every aspect of the things we see touch or do Look at a subway map and all the schedule information suddenly streams from the cloud into our Apple iPhone At the same time our GPS location goes out to the cloud along with tweets i e posts on Twitter text messages and blog updates that make a private life every thing but And unlike we skeptics devotees of the new faith have no fear of completely trusting all the software services in the cloud Of course it do
92. ill begin executing the downloaded code COMMANDING THE SYSTEM The Command Module s CD installs a development Module has plenty of flash memor y storage space to hold a useful control program Before I get into the programming of the Command Module I need to mention that the Command Module passes the I Os available on the 25 pin expansion connec tor to the user along with a bevy of extra I O controlled directly from the microcontroller These are accessed via four ePorts DB9F In addition to the extra I Os there is a RESET button a User button and a USB device por t The Table 1 The Create s basic unit runs an operating system that enables you to manipulate behavior by controlling and monitoring its I O devices through its serial port The commands listed here can be sent by any device capable of serial communications Command Opcode Data bytes 1 2 3 4 Etc Start 128 Baud 129 Baud code 0 11 Control 130 Safe 131 Full 132 Spot 134 Cover 135 Demo 136 Demos 1 to 9 Drive 137 Velocity Radius 500 to 500 mm s 2 000 to 2 000 mm Low side drivers 138 Output bits 0 7 LEDs 139 LED Bits 0 10 Power LED Color Power LED intensity 0 255 0 255 Song 140 Song number Song length Note number 1 Note duration 1 0 15 1 16 31 27 0 255 Note number 2 etc Play 141 Song number 0 15 Sensors 142 Packet ID 0 42
93. imple line following robot or various other robotics applications There is still plenty of free program memo ry in the supervisor dsPIC to add code for such tasks With minor changes in software or n one at all it can also be used by itself f or a remote controlled vehicle using the bidirectional RF modem with some ki nd of smart remote control This remote control can send complex commands such as move FWD 1 m turn 15 left run FWD at 50 cm s go to X Y coordinates o r something similar SUBSYSTEM The navigation control subsystem is shown in Figure 1 A detailed schematic diagram and pictures of every board as well as the complete project done with Cad soft s Eagle are available on the Circuit Cellar FTP site The subsystem includes the dsNavCon and an STMi croelectronics L298 based dual H bridge board for con trolling the geared 12 V motors Hsiang Neng DC Gear Motor Manufactur ing s HN GH12 1634TR The circuit of this H bridge is a classic appli cation of an L298 IC as you can see in its datasheet and application note Motion feedback comes from a couple of 300 CPR quadrature Photo 3 This is a sequence of the mobile platform starting from a square cut standard piece of expanded PVC This kind of material is available on the Net Already cut to 200 mm 200 mm 5 mm it needs just a cutter and a ruler to be shaped in such an easy way An octagonal based robot is as easy to drive a
94. ircuitcellar com March 2009 Issue 224 than 20 It has five pins three of which provide ground and 5 V power a gamma mode and an output The output signal consists of a 1 VPP composite video signal when terminated with a 75 resistor to ground To watch the camera s out put you can simply plug it into the composite input of your TV It s that simple Understanding what the camera sees is a bit harder so I ll take it one step at a time First you have to digitize the analog signal To sample slower waveforms with the Propeller you would typically use delta sigma modulation with a capacitor and a resistor But because you need to resolve the individual pixels in a frame you need a faster solution The ADC08100 is a 20 to 100 Msps 8 bit ADC W ith a clock signal it will output the digital equivalent of its input voltage on its eight digital outputs We ll use one of the Pro peller s 16 hardware counters to clock the ADC at 10 MHz and read the result from the Propeller s I O port see Figure 2 At this point your robot is ready to take its first peak at the world one scan line at a time see Photo 2 Listing 1 is a short program that uses ViewPort to trigger and display the NTSC waveform generated by the camera The program starts by configuring the Propeller s clock to run at 80 MHz and including the three objects you need The vp commands register is a component that will quickly sam ple the state of the
95. iversity of Illinois Thomas currently designs prototype systems in Umbria Italy ROJECT FILES To download code go to ftp ftp circuitcellar com pub Circuit_Cellar 2009 224 OURCES ATmega168 Microcontroller Atmel Corp www atmel com WIZ810MJ Network module and W5100 5300 Ether net controller WIZnet Inc www wiznet co kr en P S demonstration purposes The status and override are implemented with the JavaScript XMLHttpRequest facility the cornerstone of AJAX IMPROVEMENTS The ITAP was a fun project to build It was much more of a software project than a hardware project The design has proven to be simple to use and easy to explain to others There is still a learning curve to understand what zones and programs are all about but this knowledge is also required for any timer The fact that there is no expen sive LCD sitting idle in the garden is continuously comforting One serious drawback with the cur rent design is having a stati c IP address for the ITAP I did not want the ITAP to get its address by DHCP because I expect to have a laptop plugged into the ITAP while standing in the garden A reasonable alter native would be for the ITAP to play DHCP server for a laptop client WIZnet has released two addition al modules the WIZ830MJ and WIZ812MJ I have not worked with either but both appear to be better choices for new designs The WIZ830MJ has the W5300 chip The WIZ812MJ is a redesign of the W
96. le WIZnet network module Webserver data model RTC and control Solenoid driver Today live view 2903018_Bereiter qxp 2 5 2009 1 10 PM Page 32 65 qxp 11 28 2008 2 53 PM Page 1 34 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 network as a better serial line Con ceptually the ITAP has two boxes Box one is a headless control unit that mounts in the garden and is hard wired to zone solenoids It also has an internal calendar and timer that run the watering schedule Box two is a fancy LCD and keyboard that plugs into box one whenever a change of schedule is required Box two of course is really a laptop with a web browser The hardware box represents the headless control unit see Figure 1 A microcontroller maintains a data model in EEPROM that is used by the timer control firmware to determine when to turn on and turn off sole noid water valves A WIZ810MJ net work module is used by the web server firmware to accept requests Figure 2 Connectors H1 and H2 are for the WIZ810MJ module In SPI mode few of the WIZ810MJ s pins need to be connected 2903018_Bereiter qxp 2 5 2009 1 11 PM Page 34 www circuitcellar com CIRCUIT CELLAR 35 March 2009 Issue 224 the ATmega168 largely because of its 16 KB of flash memor y and because it is easily available in a DIP package simplifying prototyp ing Timer 2 is used with an exter nal 32 kHz crystal in real time clock mode
97. llar Incorporated All rights reserved Circuit Cellar 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 CHIEF FINANCIAL OFFICER Jeannette Ciarcia MEDIA CONSULTANT Dan Rodrigues CUSTOMER SERVICE Debbie Lavoie CONTROLLER Jeff Yanco ART DIRECTOR KC Prescott GRAPHICDESIGNERS Grace Chen Carey Penney STAFF ENGINEER John Gorsky Cover photography by Chris Rakoczy Rakoczy Photography www rakoczyphoto com PRINTED IN THE UNITED STATES As I ve said here before most quality new designs are the sum total of dozens perhaps hundreds of earlier projects applications and programs When you see a project in this magazine you can think of it as a single point in the long timeline of technological evolution Looking ahead you should consider each project idea and program described in these pages as a contribution to future projects You and your fellow readers will take what you learn and put it to good use during your upcoming endeavors This month we feature interesting robotics applications These robots are the progeny of countless other robotics applications that are easy to find and study Look no further than your stack of past Circuit Cellar magazines to read about many of the designs that influenced the development of the robots we use today A few Circuit Cellar articles immediate
98. ly A significant milestone for building a balancing robot involves taking a simple step accelerating to a set speed travelling and then decelerating to a stop The DanceBot uses what s known as a hybrid fuzzy logic cascading PID con troller to precisely carry out this and other advanced maneuvers In the algorithm the inputs to the PID con trollers are first processed by a fuzzy logic engine to make the control algorithm more robust and easier to tune The PID controllers which correct the error between a measured vari able and its setpoint by calculating a cor rective action are arranged in a cascade with the output of one used as the set point in the second Second while it s possible to determine tilt by optically measuring the distance to the floor this technique isn t robust The DanceBot measures rate of turn using a ceramic gyroscope and integrates this signal to calculate tilt Fusing the calculated tilt value with measurements from an accelerometer with a Kalman filter yields an accurate tilt reading with no drift This combination lets the DanceBot stay balanced in any environment The DanceBot is controlled like a car it requires two channels of information see Figure 1 Channel 1 speed controls how fast the robot should travel Channel 2 turn rate controls how quickly the robot should turn about its own axis The DanceBot manages the speeds of its two motors to stay balanced and to achieve the position orie
99. ly come to mind J Bingham and L Magnusson Inertial Rolling Robot Circuit Cellar 200 2007 E Leland et al Robot Localization and Control Circuit Cellar 188 2006 M Chao and L Ming GPS GSM Mobile Navigator Circuit Cellar 151 2003 M Dvorsky Fighting Fire with Robots How to Build a Mobile Robot Base Circuit Cellar 128 2001 J Stefan Navigating With GPS Circuit Cellar 123 2000 B Reynolds MicroBot Programming Intel s 8749 for Robotic Control Circuit Cellar 92 1998 I Cyliax Robot Navigation Schemes Circuit Cellar 81 1997 and C McManis Sensing Obstacles with Mobile Robots Circuit Cellar 73 1996 In this issue Guido Ottaviani contributes to the development of new robotics control systems In the first part of his series titled Robot Navigation and Control he describes how to design a navigation con trol subsystem p 14 Starting on page 22 Hanno Sander describes a novel vision guided robotics application His exciting balancing robot design was on display at the Embedded Systems Conference in San Jose CA last year Perhaps you saw it in action In Wireless Mobile Robotics Scott Coppersmith presents a com pact Wi Fi enabled mobile robot p 41 He mounted a webcam on the top of the robot so it can transmit real time images to a remote laptop In the final robotics related article Jeff Bachiochi i
100. ment of data to be retur ned by Create Refer back to the Sensors command in Table 1 This command requires 1 data byte 0 42 There are in fact only 36 sensor values that you can ask for so why isn t the data byte 0 35 The first seven values 0 6 request groups of sensors to be sent Value 0 requests the first 20 sensors 1 requests the first 16 2 requests sen sors 11 14 3 requests sensors 15 20 4 requests sensors 21 28 5 requests sensors 29 36 and 6 requests all 36 sensors This makes using this com mand quick Because the commands going to and sensor data being returned from Create happen asyn chronously i e your program may execute numerous instructions while the sensor data is being received you must be cautious about when you rely on new data For this reason once all the sensor data has been received it is copied into a working bank of registers for you to access This approach assures each time you access sensor data it is complete There is sensor data received e g distance and angle that must be used appropriately each time it is received These items indicate a change since the last request and are cleared inter nally within Create s OS when sent If you use the drive command to rotate counterclockwise you must Listing 1 Each sensor has its own formatting code Note that the first line of each routine has a rem d state ment that allows the routine to be skipped by removing the
101. move up in the robot s field of vision This causes the robot to move backwards and maintain a set distance from you Step ping to one side of the robot causes the pattern to move horizontally which commands the robot to turn and face you While dancing with my robot I dis covered some interesting behavior that I hadn t planned on When I jumped up or crouched down the robot would change its set distance to me When I tur ned around thereby covering the pattern the robot also turned around It no longer detected the pattern and went into search mode where it turned on its axis FIND A BEER BOTTLE I believe all robot vision ar ticles should include the beer finding prob lem Finding a specially colored beer bottle with a color camera is quite doable however you re limited to a grayscale camera You re also not guaranteed that the beer bottle will be the brightest object in the room There s no line to follow The beer bottle doesn t have a distinctive pat tern The only available trait is the actual shape of the beer bottle Use the correlation algorithm to find the shape of the beer bottle in a typical cluttered environment u This algorithm uses brute force to match a desired tem plate to all possible locations in the image The location of the best match is the location of the beer bottle The degree of match at any given point is the sum of absolute differences between the pixels of the template and the c
102. n the Roomba s proven technology FROM THE BENCH Photo 1 The Create s Power Play and Advance buttons and LEDs a and wall sensor and IR receiver b along with every other sensor can be disconnected from the interface board c Motor gearboxes with optical encoders d give the Create e a movement resolution of 1 mm Angle is determined to 1 of rotation based on the left and right encoder values b a e d c 2903002 bachiochi qxp 2 10 2009 1 45 PM Page 56 www circuitcellar com CIRCUIT CELLAR 57 March 2009 Issue 224 The Create was born with two basic models In this article I will discuss what iRobot provides as a system and how you can use the technology PROGRAMMABLE ROBOT The Create mobile robot platform is for educators and developers alike It s mobile out of the box There is no need to assemble the drive system or worry about low level code The basic unit includes a serial cable for sending individual commands from a PC or writing basic scripts of up to 100 open interface commands which can be stored on the robot Ten built in demos perform various prepro grammed behaviors More than 30 built in sensors enable the robot to react to both internal and external events see Photo 1 In addition to a serial communications port there is a 25 pin expansion port to which you can connect your own electronics sensors actuators wireless connec tions computers cameras or o
103. n the footprint of the large eight pin DIP Needless to say with so few pins there s no need for a bunch of fancy I O We re talking just the basics split between general system functions and pin oriented peripherals The list starts with an on chip regulator so the RS08 will run on any voltage you care to provide between 1 8 and 5 5 V There s also a built in clock system based on an on chip 32 kHz oscillator and a bypassable frequency locked loop The clock is trimmable to achieve 2 accuracy across the entire voltage and temperature 40 to 85 C range Given the cost cutting bias and dearth of pins I m not surprised there s no option for external clocking For robustness there s a watchdog timer low voltage detection and a multisource RESET controller that accommo dates the usual suspects such as power up power fail watchdog timeout and optionally even a pin The RESET controller also keeps the street safe for programmers by busting code that s up to no good e g illegal opcode invalid address Because no one has figured out how to get rid of power and ground the built in I O has just four DFN pack age or six SOIC DIP pins to play with Naturally any or all can be used as parallel I O with pull up and pull down options as well as slew rate con trol Any or all can also ser ve as inputs to a keyboard interrupt module KBI Recalling that the RS08 really doesn t hav
104. navigation control subsys tem for an autonomous differential steering explorer robot In the first part of this article series he describes a robotic platform that drives motors and controls an H bridge Guido also presents a communication system that remotely manages the robot Robot Navigation and Control Part 1 Construct a Navigation Control Subsystem D FEATURE ARTICLE by Guido Ottaviani uring the early stages of my electronic childhood I dreamt of building an autonomous robot But such a project was too difficult and expensive back then Now it s a lot easier with powerful inexpensive hardware and a development system that can run on a standard computer Such devices are readily available on the Internet I recently made my dream come true by building an autonomous robot In the first part of this article series I will describe the navigation control subsys tem that I designed for a differential steering explorer robot see Photo 1 The dsNavCon sys tem as I call it features a Microchip Technology dsPIC30F4012 motor controller and a general pur pose dsPIC30F3013 EXPERIMENTATION I started visiting some amateur explorer robot com petitions a few years ago I was disappointed with the robots I encountered Many seemed to move around at random Others seemed to repeat the same path several times Fortunately while searching the Internet I found Johann Borenstein s technical report Where
105. nce of the source event and entering the associated handler varies depending on the event s polling posi tion In the example shown here at top speed 10 MHz bus cycle the latency grows from about 1 to 3 s between the first MTIM timer and last LVD low voltage detect events in the polling order Actual latency may be stretched even further depending on device specific wake up delays such as the time it takes for an on chip voltage regulator or clock generator to power up and stabilize Is it conceivable to craft clever soft ware to mimic the fancy features of a hardware interrupt controller Sure a pro could probably even cobble togeth er some kind of midget RTOS Is it a good idea Probably not If in doubt I d say you re better off going with a big ger ticket part e g S08 that has a real stack and interrupts On the other hand there are many many applica tions that can easily get by with the RS08 s simple scheme When every penny counts why pay for stuff you don t need MINI MEM The initial parts in the RS08 line up come with just 1 KB MC9RS08KA1 or 2 KB MC9RS08KA2 of flash memory Follow on parts have more as you ll see shortly but remember the architecture itself accommodates only a 16 KB address space Notwithstanding the fact that RS08 code density is enhanced by the 1 byte TINY and SHORT instruc tions bloatware aspirations will surely be better served by a higher end MCU
106. nd writing a string see Listing 2 If you ve been reading Circuit Cel lar for the past few years you may remember reading articles about the FAT file system A few of the ar ti cles are listed at the end of this ar ti cle In fact Jeff Bachiochi recently completed a two part series on the topic Access SD Memory Cards Circuit Cellar 222 and 223 2009 For many of today s embedded sys tems it s likely that one feature on the requirements list is a removable memory device Years ago we actu ally put EPROMs on plug in memor y cards Remember the early video games Today you would either use a CompactFlash card or a MultiMe diaCard SD MMC To meet that requirement you need a hardware interface to the card and you have to design your own file system or use an existing file system If you want to design your own file system good luck You ve got a lot of work ahead of you and you ll need it If on the other hand you want to leverage the PC with W in dows MAC with OS X and other off the shelf computers some using Linux then look into using an existing file system With DOS Microsoft created a file system the same system that first appeared on floppy disks and evolved onto hard disks As disk capacity grew the file system changed to make room for larger capacity disks That file system is referred to as FAT FAT12 FAT16 and FAT32 Somewhere in the mix of designs long file names were include
107. ne of the top players in the MCU market since the very begin ning And judging by the fact that they ve introduced a brand new 8 bit processor core the RS08 they plan on keeping it that way FORWARD TO THE PAST To get a better understanding of what the new RS08 core is all about let s start with a bit of a history lesson Like many other popular MCUs the RS08 has roots that go way back Figure 2 The RS08 memory map reveals details about the architecture The direct address space is only 256 bytes 0 FF so higher addresses are accessed via a 64 byte paging window C0 FF New TINY and SHORT addressing modes access low memory including fast access RAM the emulated X index register and the most frequently used I O and control registers 0000 000D 000E 000F 0010 001E 001F 0020 004F 00C0 00FF 0200 023F 3C00 3FFB 3FFC 3FFD 3FFF D X Fast access RAM 14 Bytes RAM 48 Bytes Frequently used registers Pagesel Unimplemented Unimplemented Unimplemented Paging window High page registers NVOPT Flash MC9RS08KA1 Flash 1 020 Bytes Register X 0000 000E 000F Address indicated in register X 00FF 0100 D X Register X Content of the location can be accessed via D X Register X can specify any location between 0000 and 00FF Figure 3 The X index register hasn t gone miss ing Instea
108. nnels inverted if required and calculated calibrated from the raw data to obtain a set of 0 100 percent values see Photo 3 The des tination IP address and port is select ed to match the WIZnet configura tion When the Link button is acti vated UDP datagrams are sent every 250 ms with all of the data to control the robot servos At the same time an HTML page is loaded into an inte grated browser panel that polls the camera for a real time video stream The camera s IP address and video set up information is located in the HTML file In Listing 2 the first four lines poll the Microsoft multimedia driver for the current status of all the poten tiometers and switches on the select ed joystick The UpdateJoystick procedure then updates the raw data to each servo control variable and shows the status of the joystick but tons and switches The raw joystick axis values are displayed with edit Photo 4 This is a runtime form with a PICBotCam video screen Listing 6 This code is used to open an Internet browser window to show the robot camera video if panel4 Visible False then begin panel4 Visible True Webbrowser1 Visible True Button2 Caption Click for Setup OpenDialog1 Title Open BotCam HTML File OpenDialog1 FileName capperbotcam2 html If OpenDialog1 Execute then WebBrowser1 Navigate file OpenDialog1 FileName else WebBrowser1 Navigate about Error Opening File end end 290
109. ns and even a measure of system simulation capability see Photo 3 While studying the MC9RS08LA board I made an interesting discover y Look closely at the right edge and you ll see a Freescale three axis MEMS accelerometer It is shown on the schematic but otherwise isn t men tioned anywhere in the documentation 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 cantrell circuitcellar com EFERENCES 1 J Shi AN3741 Implement an In Application Programmable Data Stor age on the MC9RS08KA8 Freescale Semiconductor Inc 2008 2 V Ko AN3266 Getting Started with RS08 Freescale Semiconductor Inc 2006 OURCE MC9RS08KA MC9RS08LA and MC9RS08LE Microcontrollers Freescale Semiconductor Inc www freescale com S R 2903003 cantrell qxp 2 5 2009 12 59 PM Page 70 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 CROSSWORD The answers are available at www circuitcellar com crossword Down 1 The 3 in the data sample 9 2 3 3 3 3 8 6 6 6 1 1 3 CERN s city 5 The O in OLED 6 Mass acceleration 9 Init 10 Software added to a program to improve it 12 ASCII End of transmission 15 The last color in the visible spectr um 16 Converter to drop V 18 Balanced unbalanced Across 2 lt B gt lt B gt 4 Transforms
110. ns the byte order used when saving data Murphy s law says it won t be what you want it to be If these Endian issues are a new topic to you please look them up The GetnBits routines return the specified amount of data from the buffer Different parameters are saved as 8 16 or 32 bits for efficien cy They are packed with no padding between parameters Any size parameter could start at any memory location The LBALocation is a 32 bit number specifying the location address on the CF card Disk drives use heads cylinders tracks and sec tors to get to a specific location on a drive The CF card uses a for mula that equates the LBALocation to a head cylinder or sector notation The LBALocation is the head 8 bits cylinder 16 bits and sector 8 bits all combined into a 32 bit number APPLICATION REQUIREMENTS I think we ve got both the high level and the low level ends of the design covered All you have to do next is fill in the middle I originally wanted to write this article as a call for a FAT file system design sort of Listing 4 The lowest level CF interface routines INT16 Init_CF void INT16 CFCheck_RDY void INT16 Wait_RDY void INT16 CFCheck_RDY_ALT void INT16 Wait_RDY_ALT void UINT16 ReadRegB UINT16 addr UINT16 ReadRegW UINT16 addr UINT16 WriteRegW UINT16 addr UINT16 WriteRegB UINT16 addr void ReadCF_SectorB UINT8 dest UINT32 LBALocation void ReadCF_Se
111. nta tion and velocity goals given by its higher level plan ner Unlike a car the robot is capable of turning in place At first I controlled my robot with a remote control but I quickly realized that it would be much more fun if it could interact with others as well just by watching what they were doing The first step to guide the robot with vision was to build a frame grabber FRAME GRABBER The DanceBot s vision is controlled by a small grayscale Electronics123 com C Cam 2A miniature video camera It is just 16 16 16 mm uses less than 100 mW and costs less Figure 2 This is the frame grabber hardware The C Cam 2A outputs an NTSC composite signal in pin 3 This is digitized by the ADC08100 whose output D4 D7 is fed to the Parallax Propeller Figure 1 The DanceBot gets information from its environment through its sensors a camera a quadrature encoder a gyroscope and an accelerometer It processes this data to find its dance partner current position and tilt Fuzzy logic is used to balance and to maintain a set distance from its partner by driving the wheel motors Sensors Camera Quadrature encoder Gyroscope Accelerometer Preprocess Location of person Position velocity Tilt rate of turn Logic Find person and set target position Fuzzy PID loop to balance and achieve target position Actuators Drive two motors 2903017_Sander qxp 2 5 2009 1 11 PM Page 23 24 CIRCUIT CELLAR www c
112. ntroduces the topic of programmable robotics p 56 He describes how to upgrade and develop an existing robotics platform If you re interested in timing applications Thomas Bereiter s article is right up your alley In Networked Timing he explains how he built a timer with advanced planning tools p 31 The irrigation control sys tem generates handy information such as zone activity Turn to page 51 for a review of the FAT file system In this first part of the series George Martin covers the process of opening files and performing operations Tom Cantrell closes the issue with an article about one of his favorite topics 8 bit chips p 64 Although 32 bit chips get a lot of attention these days Tom explains that 8 bit chips are alive and well Good luck starting your next project Feel free to share your ideas and design experiences on the Circuit Cellar Discussion Board http bbs circuitcellar com phpBB2 Design Evolution cj circuitcellar com 44 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 TASK MANAGER CIRCUIT CELLAR THE MAGAZINE FOR COMPUTER APPLICATIONS 48 pin LQFP 108 pin BGA 100 pin LQFP 28 pin SOIC 64 pin LQFP 47 qxp 1 29 2009 10 58 AM Page 1 6 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 INSIDE ISSUE TASK MANAGER 4 Design Evolution C J Abate NEW PRODUCT NEWS 8 edited by John Gorsky TE
113. ocieties on a global scale Those folks are going to want lots of gadgets too There s one more bit of evidence that s testimony to the stay ing power of our little friends The fact i s all the major players in the 8 16 bit MCU biz continue to roll out n ew parts That s 16 Bit index register H X X Index register high Index register low H 15 8 7 SP Stack pointer 7 0 0 15 PC Program counter 0 A Accumulator 7 0 CCR V 1 1 H I N Z C Condition code register 64 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 Thirty two bit microcontrollers are becoming more popular but 8 bit chips still have their place in the market Tom says major companies will be find ing uses for the simple and inexpensive chips for years to come A Really Simple Plan The 8 Bits Saga Continues by Tom Cantrell SILICON UPDATE Figure 1 Judging by the similarity between the original Freescale Semiconductor MC6800 a and the modern MC9S08 b you wouldn t guess 30 years separates them By contrast the new Freescale MC9RS08 c is noticeably different 15 IX Index register 7 0 0 15 SP Stack pointer 0 15 PC Program counter 0 A Accumulator 7 0 B Register 7 0 CCR 1 1 H I N Z V C Condition code register a b 13 8 7 0 PC Program counter 7 0 A 13 0 SPC CCR Z C Condition code register Accumulator Shadow program counter c
114. oes n t affect a running program Rather it does only two things First it sets a flag bit in a register signifying the source Second it wakes up the processor if it s sleeping Needless to say without true inter rupts there s certainly no need for the fancy add ons such as vector priority and nesting schemes If you ve already thrown out the baby you may as well go ahead and throw out the bathwater Instead what passes for interrupt han dling boils down to a combination of waking up periodically and or in response to an internal or external source event and polling the event flag bits to determine the source Listing 1 shows a likely application software scenario The program is an infinite loop InfLoop that simply waits WAIT instruction in low power mode until awoken by an inter nal or external event Then the program pro ceeds P1 to scroll through the list of possible sources checking the event flags and branching via the BRSET branch if bit set instruction to the han dler for the event that generated the wake up call After the handler does its thing it returns to the beginning of the loop and goes back to sleep to wait for another call to action The polling order has two ramifica tions First it s a way to brute force the issue of priority because events higher up the list will be polled and if pending handled before those further down the list It also means latency between the occurre
115. ogs made it easy to split my goal of guiding a balancing robot with vision into manageable pieces see Photo 1b Depending on the performance required I could write the code in the high level object oriented Spin language or dive down to assem bly to write completely deterministic code The logic to configure and control the robot ended up being programmed in Spin while the frame grabber and vision filters are pro grammed in assembly Even though resources are limited it s possible to carry out advanced vision processing with it In today s age of multilevel architectures relying on outside libraries drivers and operating systems it was a breath of fresh air to program the entire chain from decoding the NTSC waveform to controlling the robot Visually debugging the DanceBot with ViewPort greatly simplified its development by showing me exactly what was going on with my robot It acted like a black box when the robot fell down and showed me what the camera and filters were processing when I was teaching it to dance It should be straightforward to adapt the code and filters presented in this article to other robots Good luck I Photo 5 The DanceBot is finding the location of a beer bottle Standards improve quality and enable designers to share components across different projects Today ARM Cortex M profile processors combined with the Cortex Microcontroller Software Interface Standard CMSIS and
116. ok at the signal the check proce dures other times you want to wait until the previous operation has completed the wait procedures Be careful You will hang the system if you are waiting for a ready signal that never materializes This probably is not a good situation in an embedded system The next four routines ReadRegB ReadRegW WriteRegW and WriteRegB all read and write to a register in the CF card Again check the literature about Compact Flash cards The CF hardware inter face provides for an 8 or 16 bit data path If you ve got a smaller system an 8 bit interface might make the most sense If on the other hand you re looking for maximum per formance the 16 bit data path is available The next four routines ReadCF_ SectorB ReadCF_SectorW WriteCF_SectorB and WriteCF _SectorW read from and write to a sector on the CF card The basic information is accessed in 512 8 bit or 256 16 bit blocks A special rou tine ReadIdentityInfoW reads words from a specific card location to get the identification infor mation about the CF card I included the prototype for reading bytes ReadI dentityInfoB but I didn t code that one because I have a 16 bit interface The next four routines CFByte Swap Get8Bits Get16Bits and Get32Bits deal with manipu lating the data that has been read from the card CFByteSwap deals with the Big Endian Little Endian issues This concer
117. only Clicking an Edit button brings up a program edit page see Photo 3 Both program tables are generated by the same JavaScript code A flag tells the JavaScript to hide or desensitize cer tain fields in read only mode The basic program interval can be set to either a fixed number of days or odd even days The check box by day of week is just an aid It is no different than selecting a one day interval The days of the week check boxes are used to modify the basic interval In an earlier design I had two rows of check boxes one for days when the program should r un and a second for days when the pro gram should not run This was not necessary because a not Friday program is logically the same as selecting every day except Friday There is always a trade off between convenience and UI clutter The Pro gram active check box is used with the planning tools To see what a particular program contributes to the overall totals it can be tem porarily disabled As you can see there is plenty of flexibility but also plenty of oppor tunity to make a mistake The plan ning tools are a simple but effective innovation that gives a glimpse into the future Based on the cur rently active programs the firmware runs the clock forward to determine how much water each zone will get each day This summary data is used to construct the calendar page see Photo 4 Each day in the calendar contains a small bar chart The let ters
118. onnec tor adding an LDO 3 3 V regulator and some signaling LEDs in a foot print that is a little bit bigger than XBee itself Refer to the Resources section for more information about the XBee simple board and XBee USB board adapters Because you have the physical layer and the protocol for communi cation you need an application layer that shows the results on a computer screen A good tool would be the National Instruments LabVIEW graphical development or LabWin dows CVI C language compiler and IDE with all of the easy to use widgets and primitives to develop a control panel or a virtual instru ment But its price is professional which means it is costly Still I rec ommend looking at the full working timed demo I used my own widgets and instru ments with a simpler development system I wrote the console with the Processing open source programming language and environment and with the aid of the Interfascia graphical user interface library Refer to the Resources section at the end of this article for more information Pro cessing is a simple multiplatform environment that produces Java exe cutables for Windows Mac OS X and Linux operating systems It fits my requirements for software shar ing perfectly Three panels make up the console The main panel or navigation panel controls the robot s movements You can set values with a knob for angle or input fields for speed dis tance or target coo
119. or slowly turned a wheel with on off pins If you wanted water at 6 A M in zone 2 you simply pushed in the pins for zone 2 and 6 A M The wheels and pins also ser ved as crude analog gauges A glance at the wheel would give you a pretty good idea of when things would next tur n on and for how long In the electronic age the wheels and pins are gone They have been replaced by a tiny LCD and a small keypad The e lec tronics have added significant new capabil ities but at the cost of requiring signifi cant data entry with a tiny keypad The visual feedback about what you ve pro grammed is also gone To ensure that you have not accidentally programmed a 4 h flood you need to page through identical screens taking note of each setting As you can see in Photo 1 I designed Photo 1 This is the completed circuit board The WIZnet WIZ810MJ is the red board with the RJ 45 connector A solenoid valve connected to a manifold is to the left of the circuit board 2903018_Bereiter qxp 2 5 2009 1 10 PM Page 31 32 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 an Irrigation Timer with Advanced Planning capability ITAP The challenge was to incorporate moder n func tionality yet keep the design as simple to use as the old electromechanical design Because the biggest problem was entering and displaying large amounts of data I selected a web browser for the user inter face I consid ered various USB based w
120. orresponding pixels of the area to match To improve the robustness of the algorithm against changes in brightness and contrast I preprocess the template and every possi ble match with an auto level algorithm This algorithm does a good job of finding beer bottles Photo 5 shows the target identified in a complex environ ment However the image of the bottle must be a close match to the template i e its scale and orientation must be Listing 4 This Propeller assembly function sums the horizontal position of the darkest pixel to steer the robot along a black line For each horizontal line it uses t3 to track the location of the minimum brightness and adds this to t2 at the end of the line doLowest rdlong t1 cmdPtr t1 is the address of the result variable We ll write the x position of the line here add cmdPtr 4 mov t2 0 t2 is sum of pos mov n linesNpanel loop over panel loopLines mov x longsNline loop over line sub x 2 mov val 15 reset val loop rdlong old src loop over longpixels add src 4 mov m 8 mov new 0 limit mov tmp old and tmp 15 cmp tmp val wc c set if v1 lt v2 if_c add new 15 if_c mov val tmp if_c add new 15 if_c sub val 1 if_c mov t3 x t3 is pos of lowest item ror new 4 ror old 4 djnz m limit wrlong new dest add dest 4 djnz x loop loop over longpixels add t2 t3 add src 8 add dest 8 djnz n loopLines loop over lines wrlong t2 t1 jmp cmdLoo
121. ower 32 bytes of the address space are uniquely accessible with single byte versions of the most common instructions Instruction Addresses INC 00 0F DEC 00 0F ADD 00 0F SUB 00 0F CLR 00 1F LDA 00 1F STA 00 1F Listing 1 The way the RS08 handles interrupts is simple It doesn t Instead an interrupt simply sets a bit in a flag register and wakes up the processor It s up to software to figure out what s going on and what to do about it InfLoop sta SRS Bump COP wait P1 brset SIP1_MTIM SIP1 MTIM_ISR 5 bus cycles P2 brset SIP1_ACMP SIP1 ACMP_ISR 5 bus cycles P3 brset SIP1_KBI SIP1 KBI_ISR 5 bus cycles P4 brset SIP1_RTI SIP1 RTI_ISR 5 bus cycles P5 brset SIP1_LVD SIP1 LVD_ISR 5 bus cycles Bra InfLoop MTIM_ISR lt ISR coding gt bra InfLoop ACMP_ISR lt ISR coding gt bra InfLoop KBI_ISR lt ISR coding gt bra InfLoop RTI_ISR lt ISR coding gt bra InfLoop LVD_ISR lt ISR coding gt bra InfLoop 2903003 cantrell qxp 2 5 2009 12 59 PM Page 66 www circuitcellar com CIRCUIT CELLAR 67 March 2009 Issue 224 right The RS08 simply doesn t do interrupts at least in the conventional sense There is a measure of attention get ting capability from the usual sources i e internal peripherals and external pins However unlike a conventional interrupt scheme a source request d
122. p 2903017_Sander qxp 2 5 2009 1 11 PM Page 28 www circuitcellar com CIRCUIT CELLAR 29 March 2009 Issue 224 Hanno Sander hanno mydancebot com has been working with computers since he programmed a lunar lander game for the z80 when he was six Since then he graduat ed from Stanford University with a degree in computer science and then started his corporate career as an Internet entrepreneur Hanno moved to New Zealand in 2005 to spend time with his growing family and develop sophisticated yet affordable robots starting with the DanceBot His technical interests include computer vision embedded systems industrial control control theory parallel computing and fuzzy logic ROJECT FILES To download code go to ftp ftp circuitcellar com pub Circuit_Cellar 2009 224 OURCES C Cam 2A Miniature video camera Electronics123 com Inc www electronics123 com ADC08100 ADC National Semiconductor Corp www national com Propeller Parallax Inc www parallax com P S identical With additional processing power multiple templates could be searched in succession or parallel to more robustly identify the bottle Once identified a faster less processor taxing algorithm could be used to steer the robot to the beer bottle in real time WRAP UP I ve had a lot of fun building the vision guided DanceBot with the Paral lax Propeller and ViewPort The Pro peller s unique architecture of eight identical c
123. ple LCD on a robot A standard display e g 4 20 compatible with the Hitachi 44780 protocol is inexpensive and easy to program But it s not easy to use It cannot show a lot of infor mation at the same time and it is slow Plus it is attached to a moving vehicle Excluding graphic displays for the same reason and because they are expensive and hard to program a good solution would be a wireless system that exchanges data with a computer on which it s easy to display the num bers even in graphical format and to store large amount of bytes Photo 5 The new board based on the Microchip dsPIC33F is a lot simpler in terms of both hardware and software than the previous one Photo 6a The navigation panel shows the robot s current position and the path The knob and input fields enable you to control navigation b The details panel shows the present value for each motor s current and a graph with the trend of the speed values for both wheels a b 2903015_ottaviani qxp 2 5 2009 1 18 PM Page 18 www circuitcellar com CIRCUIT CELLAR 19 March 2009 Issue 224 connect an XBee module to a PC via USB They are versatile reliable and easy to use with just one problem For some reason the MaxStream developers decided to install an unusual contact strip with a 2 mm metric pitch instead of a standard 100 mil pitch Fortunately someone designed a board that adapts the XBee pins to a standard strip c
124. r subelements e g lt image gt or lt script gt tags the browser will likely issue simultaneous requests If a WIZnet socket is in LIS TEN state it will accept a connection If the browser attempts a connection for which there is no listening socket the browser will get a connection refused error Depending on the browser this could result in either a reported error or a noticeable delay before a retry The workaround is to keep the pages simple with few are on opposite sides of the DIP package making layout much easier on a single sided board The only user feedback from the hardware are the WIZ810MJ s two network status LEDs and an LED driven by the microcontroller The microcontroller driven LED blinks out either a hint at the IP address or an indication of solenoid status DATA MODEL There are a number of ways to organize a watering schedule Sever al vendors have agreed on a single model which is the one used here First there are zones which corre spond to a physical run of pipe con trolled by a solenoid valve Then there are programs which indicate which days of the week and at what time of the day to star t an action Make a table and put the zones in the rows and the programs in the columns At the intersec tions decide if and for how long a zone should be on for each program This can get somewhat complex but it provides a good deal of flexi bility for things like long slow soakings and
125. rdinates see Photo 6a Instruments return the actual values for mean speed total current for both motors and orienta tion The graph shows the current position and the path The configuration panel contains the input fields for all of the constant parameters used to set up the pro gram Values are stored in the DSC s flash memory once they are sent They can be saved in a file on the computer side The details panel shows the speed and current values for each motor see Photo 6b The graphical representa tion of speed is essential to set up Speed PID K parameters because it reveals how the motors respond to variations in load or required velocity CALIBRATION PROCEDURES Once the right communication pro cedure and display of data is running you can start the setup There are many online documents about the proper calibration procedures for the PID constants both theoretical and practical Most of them are valid A simple method that is applicable in this situation is explained in Microchip s code example CE019 3 NOW WITH DYNAMIC LIVE 3D PCB DESIGN Streamline the entire electronics design process within a single uni ed solution www altium com view demo Seeing is believing Visit Altium s next generation electronics design solutions today gt Rapid prototyping using a live interactive recon gurable hardware development system gt A smooth path from concept exploration through live 3D PCB
126. read one character int fputc int c FILE fp write one character 2903013 martin qxp 2 5 2009 1 19 PM Page 51 52 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 memory card it will come prefor matted in one of the FAT file sys tems The problem you are going to run into using the off the shelf cards is the same problem you had with EPROM memory devices The size of the devices keeps growing and the one you designed with is no longer available or is available only at a higher cost Try to purchase a 1 KB EPROM or even a 32 KB device If you need only 32 MB on a memor y card that s great today But someday you ll find that size is no longer manufactured As the device card grows an older file system won t be able to access the entire available memory And changing file systems is a big task It looks like I ve come up with more issues than answers or even the hope of answers So let s get into the next part What are we going to do From the top of the design pile if you look at the C lan guage you ll find it supports file I O You ll find a good description at http en wikipedia org wiki C_file_ input output FILE OPs amp PROTOTYPES The most basic file operations are open close read and write Their prototypes in C are in Listing 1 There are alternatives to the basic reading and writing of one character at a time One common pair of pro cedures is reading a
127. regulator circuit sim ilar to the one for the PIC24FJ64GA002 A smart charging station with temper ature probes and maybe some Lithium polymer battery packs will have to go on my WiFi PIC Bot upgrade some day list Photo 2 shows the inside of the control box with some of the battery packs speed control PIC24FJ64GA002 PCB and WIZ810MJ PCB installed Cooling fans are mounted on the sides of the box for the power supplies and speed con trol circuits and run off of the 12 V supply A switch for the speed control along with switches for the power sup plies and fans are also mounted on the sides of the box I left a connector inside to disconnect the motor supply batteries while I fiddle around with software and such so the robot won t drive off the table unexpectedly from a code error A table top robot hoist will also have to go on the to do list I left the original RC connectors on the speed control and steering servos so I could still drive the robot around with the RC transmitter and receiver and test the speed control by itself if needed EMBEDDED CONTROLLER The embedded Ethernet board speed control and servos for controlling steering camera pan and tilt are wired to a Microchip DM300027 16 bit 28 pin development board see Figure 1 I replaced the original crystal with an 8 MHz crystal to gain some speed and installed a PIC24FJ64GA002 proces sor The WIZnet board is connected to the DM300027 developmen
128. reverse and I didn t have one However I had a Novak T 4 electronic speed control in my stash of RC parts and a collection of high current MOSFETs It was time for a bit of reverse engineering Under the hood of the original T 4 the circuit had six small FETs in parallel for forward speed and one FET for braking with no reverse After a day of head scratching and PCB probing with my oscilloscope Figure 1 This is the WiFi PIC Bot Listing 1 This is servo control output compare 1 setup code Output compare pin setup RPOR3bits RP6R 18 Make Pin RP6 RB6 OC1 OC1CONbits OCTSEL 0 Use Timer 2 data OC1CONbits OCM2 1 Use PWM mode OC1CONbits OCM1 1 OCFA fault detection disabled OC1CONbits OCM0 0 OC1R 0x0400 OC1RS 0x0c00 Set timer compare value for servo center position IFS0bits OC1IF 0 Clear interrupt flag IEC0bits OC1IE 1 Enable the interrupt Timer 2 setup TMR2 0 Clear the timer PR2 0x9000 Set the servo update time for 20 ms T2CONbits TCKPS1 0 Set the timer prescale 1 8 T2CONbits TCKPS0 1 T2CONbits T32 0 Set the timer for 16 bit mode IFS0bits T2IF 0 Clear interrupt flag IEC0bits T2IE 1 Enable the interrupt T2CONbits TON 1 Turn the timer on 2903014_Coppersmith qxp 2 5 2009 4 32 PM Page 43 44 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 I determined that I could remake this controller into a
129. rnet Discussion Group recently spent some time designing a competition As mechanical insects walked around our meeting table among all the pizza beer and red wine we drafted a set of r ules for the Robo Tolomeo Cup RTC compe tition We named it the Robo Tolomeo Cup in order to refer ence the great Greek cartographer Remember navigation is key for any mobile robotics system The rules are simple Each robot must start from point A navigate to point B at least 10 m away and then return to point A This must be done with pure dead reckoning without any external reference while avoid ing a few convex obstacles just so the path is not a straight line The score is inversely proportion al to the distance from the marked returning point at the end of the session A Rino like system the dsNav Con board and the theory behind it are all an entrant needs to build a robot for this kind of competi tion The first experimental com petition is scheduled to take place this year We are intention ally keeping it low profile with out sponsors or prizes The only prize is the satisfaction of finish ing a project If there are enough participants who submit interest ing designs we may plan another more involved competition The RTC could be considered an indoor version of or stepping stone toward a larger event such as the Robo Magellan outdoor robotics competition Who knows what the future will bring 2903015_o
130. robots and collecting robots I named it Rino which rhymes with Robottino or little robot in Italian see Photo 3 BASIC PRINCIPLES The 300 CPR encoders are connected to the motors axles Because the wheels spin at up to 200 RPM and the gear reduction ratio is 30 1 the axles can spin at 6 000 RPM To catch all of the pulses generated by the encoders in a 4 decoding method 120 kHz I needed dedi cated hardware for each encoder After experimenting with the Microchip PIC18F2431 motor control microcontroller it was time to upgrade to the dsPIC30F digital signal con troller series DSC A dsPIC30F4012 motor controller for each motor is perfect for controlling wheel position and speed and for performing odometry Data provided by the two motor controllers is collected by a dsPIC30F3013 This general purpose DSC has enough power to get data and perform some trigonometry to calculate position coordinates and store data related to the path covered to obtain a map of the field all at a high rate This brings me to the dsP IC based navigation control board the dsNavCon This board is designed to be par t of a more complex system In a complete explorer robot other boards will control sound light and gas sensors as well as bumpers and ultrasonic ra nge finders for locating targets and avoiding obstacles A behavior board will decide how to act to reach the goal As a stand alone board the dsNavCon can be used for a s
131. rocontrollers Atmel has combined more than ten years of low power research and development into picoPower technology picoPower enables tinyAVR megaAVR and XMEGA microcontrollers to achieve the industry s lowest power consumption Why be satis ed with microamps when you can have nanoamps With Atmel MCUs today s embedded designers get systems using a mere 650 nA running a real time clock RTC and only 100 nA in sleep mode Combined with several other innovative techniques picoPower microcontrollers help you reduce your applications power consumption without compromising system performance Visit our website to learn how picoPower can help you hammer down the power consumption of your next designs PLUS get a chance to apply for a free AVR design kit Hammer Down Your Power Consumption with picoPower http www atmel com picopower THE Performance Choice of Lowest Power Microcontrollers picoPower 2008ad indd 1 8 8 2008 8 35 17 AM 11 8 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 CPLD DEVELOPMENT KIT The new picoUSB development kit for Altera s MAX3000 and MAX7000 families of CPLDs enables you to economically learn Altera CPLD design With its USB interface picoUSB in system programming can be easily managed from your PC It is an ideal solution for introductory digital logic design courses The picoUSB uses a 44 pin PLCC socket to support the MAX3000 and 7000 devices With the free
132. roducing new segment LCD parts For the simplest i e fewest segment apps you may be able to get away with a software bit banging static approach that devotes a pin to each segment But the number of segments and thus pins required can balloon fast For example a single alphanumer ic digit requires up to 16 segments Enter the multiplexed alternative which like a core memory of yore uses an XY frontplane and backplane in LCD speak electrode scheme where a single pin controls multiple segments in a time division fashion slashing the number of pins required For instance with 24 pins a static controller can handle 24 segments By switching to a multiplexed scheme with four back planes and 20 front planes the same 24 pins can accom modate 80 segments The approach ups the ante in ter ms of processing and electronics complexity LCD glass can be finicky with its demands for phase shifting AC and care fully controlled voltage levels to avoid creating nearby ghost segments High segment count multiplexed LCD control is one of those duties where a little hard ware can go a long way to make life eas ier for designers Featuring 4 1 and 8 1 mux options the 28 pin MC9RS08LE and 44 pin MC9RS08LA can handle up to 112 and 168 segments respectively Embellishments include a pin map ping feature that facilitates PCB and connector layout to reduce EMI and crosstalk There are also a variety of power options t
133. ry into RAM for execution because flash memory access e g instruction fetch is not allowed during programming The technique is rather scary and fraught with peril because once flash memory programming is underway any hiccup Oops I forgot to disable the watchdog timer could leave the part brain dead And while it s nice that code can be executed from RAM don t get too excited because the MC9RS08KA1 and MC9RS08KA2 give you only 48 bytes to play with SMART DUST Sticking with the small is beautiful theme the MC9RS08KA1 and MC9RS08KA2 come with just six or eight pins The largest if you can call roughly 6 mm 10 mm large of these is a vintage eight pin DIP which is useful for prototyping or cheap e g single sided through hole PCBs You can cut the DIP s already small footprint in half by going surface mount with the option al eight pin leaded SOIC package at just Photo 1 The RS08 six pin DFN package is so small it will erase your board space concerns 2903003 cantrell qxp 2 5 2009 12 59 PM Page 67 68 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 5 mm 6 mm If you re willing to give up a couple of pins the six pin actually no pins just pads dual flat nonleaded DFN package represents a new low in board space This Chihuahua is amazingly small at just 3 mm on a side and 1 mm thick see Photo 1 Consider that you can cram half a dozen of the DFN parts i
134. s a circular one but it s much easier to build Photo 2 These are my first experiments with homemade encoders a This is a hacked mechanical mouse b I used a different kind of geared motor with mouse parts c I used photoreflectors on a printed wheel a b c a b c d 2903015_ottaviani qxp 2 5 2009 1 18 PM Page 15 16 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 encoders US Digital E4P 300 079 HT miniature optical kit encoder A 12 AA NiMH cell battery pack with a nominal voltage of 14 4 V and 2 700 mAh supplies the power see Photo 4 This ensures the correct voltage for the motors after the loss of the H bridge A couple of LM7809 regulators drop down the 14 4 V to 9 V for a logic board s power supply The voltage regulators are decoupled with a capacitor input Pi filter on each one This system reduces interference from the motors and enables the use of a smaller heatsink for the 5 V regula tors on each individual board The power supply on the dsNavCon board also provides 3 3 V for the ZigBee RF modem MaxStream s now Digi International XBee module and 2 7 V reference voltage for the motor con trollers ADC This converter is used to read the motors s current through a 0 27 shunt resistor on each H bridge and a couple of op amps with a gain of 1 0 on the dsNav Con board The supervisor communicates with the behavior board of the robot through an I 2C bus and wi
135. s memory with a PC application This enabled me to mon itor and change variables while the other seven cogs ran at full speed When I added a module that sampled all 32 I O pins at 80 MHz other designers became interested in using my application to debug their integration code and ViewPort was born Since then I ve added other capabilities to the ViewPort application to turn it into a complete debugging package You can download a free 30 day trial of ViewPort at http mydancebot com THE DanceBot After watching friends demonstrate their iRobot Roomba robotic vacuum cleaners at a party I won dered if I could build a balancing robot that could dance not just with me but with anyone in any environment I wanted to build a robot that could dance with people and seem almost human Balancing robots make a great platform for mobile robots They are highly maneuverable have great traction and move more smoothly and naturally than other designs They can turn on a dime navigate precisely and are a pleasure to watch while they keep their balance Unfortunate ly building a robot that balances and maintains position robustly in any environment is not easy The first lesson I learned was that unlike the inverted pendulum problem a true balancing robot requires two control loops one control loop to keep the robot from falling and another to keep the robot from losing its position This combination also lets you move it programmatical
136. signers to share components across different projects Today ARM Cortex M profile processors combined with the Cortex Microcontroller Software Interface Standard CMSIS and optimized middleware from the industry s largest ecosystem are setting the hardware and software standards for microcontrollers These standards enable leading vendors such as Luminary Micro NXP and STMicroelectronics to supply advanced microcontrollers while maximizing code reuse across multiple platforms Standards Make Sense The strengths of ARM processor based NXP microcontrollers are fundamentally changing digital products by combining ease of use with high connectivity and low power consumption Geoff Lees Vice President and General Manager Microcontroller Product Line Cortex M3 Microcontrollers Make Sense For more information visit www onARM com The Architecture for the Digital World ARM Ltd AD158 2 01 09 Find us at Embedded Systems Conference San Jose March 30 April 3rd ARM Stand 1502 NXP 1010 2903017_Sander qxp 2 5 2009 1 11 PM Page 27 28 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 find a black white striped pattern To make your pattern visible at differ ent distances repeat the pattern at vari ous scales When you place this patter n on your belt you can start dancing with your robot Stepping closer to the robot makes the image of your patter n
137. t board by wire wrapping the header connector pins directly The two boards commu nicate via the SPI bus RB10 is used as the slave select pin RB5 and RB6 are the PWM outputs from OC1 OC2 is used for throttle and steering ser vo control OC3 and OC4 are used for camera pan and tilt servo control I also wired RB3 with a resistor divider 10 1 and a 3 3 V Zener clamp for a battery voltage monitor The resistor divider is required because the three battery packs in series at full charge can be up to 27 V SOFTWARE There are two separate software packages in this system The first is the embedded code for the PIC and the second is the UDP client on the external laptop The RC servos oper ate from pulses produced by the PIC24FJ64GA002 s timers They are available on the output compare regis ter pins The published RC ser vo pulse width specification is 1 to 2 ms although I ve found that some ser vos need a larger range of pulse widths for control of their full span capability If you send a pulse that is too small or too large however some servos will keep their internal motors on and Photo 3 This is a PC control program joystick setup and calibration form Listing 2 This is the main loop timer routine executed every 250 ms procedure TForm1 Timer1Timer Sender TObject begin LJoyEx dwSize sizeof LJoyEx LJoyEx dwFlags LJoyEx dwFlags and JOY_RETURNALL joygetpos JoystickID LJoy joyGetPosEx JoystickID
138. t stability as a result of independent operation The module provides Ethernet to wireless bridging enabling a wired network device to have a wireless communication inter face It also offers a serial interface for serial to wireless applications and offers an AP Station Gateway mode The WIZ610wi offers a 54 Mbps data rate and a maximum 20 Mbps effec tive data transmission rate The mod ule includes a full featured network protocol stack and a built in web serv er for configuration via a standard web browser The WIZ610wi including antenna costs 41 90 each The WIZ610wi EVB evaluation board costs 99 WIZnet Inc www ewiznet com npn224 qxp 2 10 2009 10 42 AM Page 12 www circuitcellar com CIRCUIT CELLAR 13 March 2009 Issue 224 Test Your Edited by David Tweed CIRCUIT CELLAR What s your EQ The answers are posted at www circuitcellar com eq You may contact the quizmasters at eq circuitcellar com EQ Problem 3 Explain the concept of a shell envi ronment What for example is PATH Problem 4 What are some of the key ways in which GUI shells are different from text shells David Tweed contributed the four problems and answers in this issue Problem 1 What is a shell program Give some examples Problem 2 What exactly does a shell do eq 224 qxp 2 5 2009 9 24 AM Page 13 14 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 Guido built a
139. t to stop from going down this path for the remainder of this column Instead I want to focus on the Create s advanced unit adding the command module to the 25 pin expan sion connector in the forward end of the cargo bay COMMAND MODULE You can use a PC to enter open inter face commands that the Create can receive via its serial por t and execute in its operating system The command module uses an ATmega168 flash memory microcontroller to send com mands to the Create This is accomplished by writing a control program and programming it into the microcon troller The control pro gram uses the open interface commands to access the Create s func tions How is this any different than typing commands to the Create through the tethered serial port It s not However the complicat ed answer is much more satisfying The most obvious dif ference is that the tether disappears because the Command Module rides piggyback on the Create Second I don t know about your typing speed or accuracy for that matter but the micro controller can send com mands at blazing speeds Here comes the most important fact Even if I could type a drive and read sensor commands fast enough I would not be able to check all of the important sensor states and decide to stop before I hit the wall on the other side of the room or ripped out the tether The Command For every 4 5 mm difference in travel distance between the two wheels
140. ted to run this program continu ously to sample video from the cam era at 30 fps with a resolution of 240 pixels 200 lines 4 bits pixel Listing 2 is an example program that uses the VideoCapture object This program configures the clock and imports some objects and then star ts the video cog to capture frames Then it configures ViewPort to display the streamed video The Spin code draws a thick black line in the middle of the frame by setting parts of the array to 0 Photo 3 shows the project s first view of the world REAL TIME TRACKING You know how to create the infra structure to digitize video from a cam era into the Propeller s memory using an ADC and one of the Propeller s eight cogs You have 24 KB of visual data updated 30 times per second Now you need a filter that can analyze the video and give you just two vari ables to control the robot Start by implementing a filter that identifies the location of the brightest spot in each frame It s easy to search for the maximum value in your array of pixel brightness values Just remember Listing 1 This Spin program sets the Propeller s clock to run at 80 MHz and includes several objects Con duit to graph the ADC s waveform via ViewPort on the PC QuickSample to sample the Propeller s I O pins and Synth to generate the 10 MHz clock signal for the ADC Running this on the Propeller enables you to display the NTSC waveform as sample
141. th a remote PC via a ZigBee RF modem for telemetry UART2 RX2 TX2 The supervisor drives both motor controllers MCs through UART1 RX1 TX1 communication sending commands and reading information space speed and motor cur rent The motor controllers have no oscillator hardware the supervisor provides them with a 7 3728 MHz signal obtained by an Output Compare simple PWM peripheral A 1 ms timing signal is also provided by the supervisor to synchronize every operation The supervisor controls motor controllers communications and other operations through the use of chip select I O signals DESIGN EVOLUTION New components are always hitting the market My first PID program was developed on a Microchip PIC16F877 micro controller with a quadrature encoder interface performed in Figure 1 This is the navigation control subsystem LEDs QEI IC OSC 0 5 V VREF 5 V LEDs 5 V 9 V 14 4 V 3 3 V VREF INT 0 RB3 INT 1 RX TX OSC 7 37 MHz NiMh Battery pack 12 AA cells 2 700 mAh On board power supply Navigation control system Preregulator 9 V Clock 1 ms Supervisor CS 2 TX EN 2 CS 1 TX EN 1 TX 1 RX 1 I2C ADC PWM 14 4 V 3 3 V H Bridge 1 Main board RF Modem Rotary encoder 1 Motor 1 Motion feedback Current sensing Serial 2 RX2 TX2 Motion controller 1 OSC 0 INT 0 RB3 INT 1 RX TX 14 4 V H Bridge 2 Rotary encoder 2 Motor 2
142. the orientation will change 1 With any thing other than point contact of thin wheels you can guesstimate only the actual turning radius This will vary greatly depending on which part of a wide wheel is making contact with the floor That s why navigation by dead reckoning loses accuracy over time This could be corrected by using an electronic compass to determine direction instead of dead reckoning Compasses aren t necessarily perfect either So in the big scheme of things it s best to not put all of your eggs in one basket This is getting beyond the scope of this article so let me just caution you in most cases you can rely on the angle for immediate results i e turning around but don t depend on it to keep track of your direction over the long ter m i e trying to set up parallel sweeps to cover a large area Let me make one last n ote about the commands in rows 23 25 see Table 1 The Script commands enable you to record and play back a number of consecutive commands When used in conjunction with the W ait commands you can have the Create per form a prepro grammed sequence of events Here is an example wait distance 1 000 mm wait angle 90 wait dis tance 1 000 mm wait angle 90 wait distance 1 000 mm wait angle 90 wait distance 1 000 mm and wait angle 90 which when played back commands the Create to drive in a 1 m 1 m square pattern SERIAL TETHER The Create can pla
143. ther hardware The cargo bay has various threaded holes for securely mounting your own brand of hardware You can add a fourth wheel to improve the stability of larger payloads but this slightly reduces its ability to adapt to changes in grade The advanced unit includes the iRobot Command Module for on board autonomous programming The Create is fully compatible with all iRobot Roomba accessories including rechargeable batteries a power supply a home base a remote control and virtual walls The Com mand Module screws onto the 25 pin expansion port at the front of the cargo bay It contains an Atmel ATmega168 microcontroller that communicates with the Create through a serial connection in the expansion port It is programmed via a USB port Let s begin with a look at the basic unit s array of peripheral I O devices UNDER THE HOOD The Create is preprogrammed with an operating system that enables access to all of its input and output devices by passing commands via a serial communications port default the passive mode the Create accepts only the Baud Safe or F ull com mands Safe and Full are similar commands that give you complete control using any of the oth er com mands Safe mode as its n ame implies has some automatic self preservation actions which prevent it from falling off an edge for instance In Full mode if you don t pay attention to its cliff sensor for instance it would attempt to fly
144. tions In this section you ll build a filter that uses your existing frame grabber to perform line following with a camera Again your frame grab ber gives you too much information so you need to design a filter that will steer a robot in the middle of a line Tilt the robot s camera so its field of view is from below the horizon to just in front of the robot Now you can stream the video to ViewPort and ana lyze what the video of a properly programmed robot would do It will become appar ent that a good algorithm involves aver aging the location of the darkest pixel in each line This is quite robust easy to program and gives a good control signal to the robot Again integrating this filter with the rest of the DanceB ot is straightforward Just use the average position of the line to control the direction of the robot while it s moving along at a set speed see Listing 4 TRACK A PATTERN You ve gone from tracking an active bright spot to following a passive line on an artificial background Now it s time to track a passive patter n in the real world The goal for this section is to develop an algorithm and patter n that will steer the robot in any envi ronment As an experiment take a Listing 2 This Spin program sets the Propeller s clock and includes two objects to find a blob Conduit to stream the video signal to the PC and VideoCapture to grab the frame By continually setting vide
145. ttaviani qxp 2 5 2009 1 18 PM Page 20 www circuitcellar com CIRCUIT CELLAR 21 March 2009 Issue 224 ROJECT FILES To download code go to ftp ftp circuitcellar com pub Circuit_Cellar 2009 224 EFERENCES 1 J Borenstein H R Everett and L Feng Where am I Sensors and Methods for Mobile Robot Positioning Technical Report University of Michigan 1996 2 D Anderson SR04 Robot Roy M Huffington Depar tment of Earth Sciences Southern Methodist University www geology smu edu dpa www robots sr04 3 Microchip Technology Inc dsPIC30FCode Examples CE019 Propor tional Integral Derivative PID controllers amp closed loop control 2005 www microchip com stellent idcplg IdcService SS_GET_PAGE amp nodeId 2620 4 J Borenstein and L Feng UMBmark A Method for Measuring Comparin g and Correcting Odometry Errors in Mobile Robots 1994 www personal umich edu johannb umbmark htm ESOURCES B Fry and C Reas Processing web site www processing org Interfascia graphical user interface library http superstable net interfascia Droids SAS XBee Simple Board 990 001 www droids it data_sheets 990 001 20datasheet pdf XBee USB Board www droids it data_sheets 990 002 20datasheet pdf G Ottaviani www guiott com Rino index html Roboteck Discussion Group http it groups yahoo com group roboteck Italian or http groups yahoo com gro
146. up roboteck_int English STMicroelectronics Application Note Applications of Monolithic Bridge Dri vers AN240 1288 1995 L298 Dual Full Bridge Driver 2000 OURCES Eagle Software CadSoft Computer www cadsoftusa com HN GH12 1634TR Motor Hsiang Neng DC Gear Motor Manufacturing Corp www hsiangnengmotors com tw XBee Module Digi International Inc www digi com PIC16F877 Microcontroller PIC18F2431 microcontroller dsPIC30F3013 digital signal controller dsPIC30F4012 motor controller and dsPIC33FJ64MC802 micro controller Microchip Technology Inc www microchip com LabVIEW and LabWindows CVI National Instruments Corp www ni com labview E4P 300 079 HT Miniature optical kit encoder US Digital www usdigital com P R S R Author s note Along with other mem bers of the Roboteck Internet Discus sion Group I helped create a design competition for robotics enthusiasts For more information about the Robo Tolomeo Cup RTC refer to the RTC Competition sidebar Guido Ottaviani guido guiott com has worked with electronics and ham radios for years After working as an analog and digital developer for an Italian communications company for several years Guido became a sys tem integrator and then a technical manager for a company that develops and manages graphic prepress and press systems and technologies for a large Italian sports newspaper and magazine publisher A
147. useful to show my stan dard tools approach to compiling files into flash memory see Listing 1 This Linux shell script takes each file compresses it converts it to ASCII hexadecimal and wraps the result in a data declaration ready for a C language include statement USER INTERFACE Photo 2 shows the ITAP s main schedule page To keep the size small only standard buttons and standard fonts were used The sched ule page is implemented as one large HTML FORM Inside the FORM is a TABLE built dynamically with JavaScript Only a small bit of HTML is used to define the basic Photo 5 Clicking on a specific day in the calendar view brings up this page which shows when the zone will be active 2903018_Bereiter qxp 2 5 2009 1 11 PM Page 37 table and headings Each page in the UI contains the same first line lt script language JavaScript type text javascript src pdata js gt lt script gt This code loads the current program and zone data Based on the number of programs and zones columns and rows are dynamically added and pop ulated with their values JavaScript functions take care of details like converting between minutes and hour and minute values There are three programs and four zones in Photo 2 The empty fields indicate that the corresponding zone is off during that program To keep the main schedule page from getting too cluttered only a summary of the program values is shown and they are all read
148. ver and others Internet controller mode can be used with any of the hardware interfaces Nano LANReach includes USB SPI and fast UART inter faces for easy integration into existing or new designs In addition to SerialNET it supports 10 simultaneous TCP UDP sockets two listening TCP sockets SMTP MIME POP3 FTP Telnet and HTTP HTTPS clients and an HTTP HTTPS embed ded web server with a web site for the host application and one for configuring the module Nano LANReach also sup ports AES 128 256 SHA 128 192 256 3DES the SSL3 TLS1 protocol for a secure client socket session and a secure FTP session The Nano LANReach starts at 38 The 160 II EVB 363ML evaluation board provides an easy environment for developing applications and testing Connect One www connectone com npn224 qxp 2 5 2009 3 29 PM Page 11 12 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 VIBRANT THREE COLOR DISPLAYS READABLE UP TO 600 The Plant Floor Marquee PFM is a series of highly visible multicolor LED displays optimized for communicating critical machine status and production data instantly across the plant floor The largest PFM is easily readable at distances up to 600 182 m The PFM series features a graphical three color dis play available in four sizes that can convey production tar gets machine faults and other custom messages The PFM takes advantage of the powerful features of a G3 series HMI Data
149. wheels mounted on motors with quadrature encoders the logic board powered by the Parallax Propeller and the miniature camera with an ADC module b This autonomous balancing robot uses vision to interact with users Here it s getting ready to balance a champagne flute for a month a b 2903017_Sander qxp 2 5 2009 1 11 PM Page 22 www circuitcellar com CIRCUIT CELLAR 23 March 2009 Issue 224 process captured video and control motors I focused on parts of the problem and later integrated ever ything by assigning different algorithms to their own cogs The Propeller has eight 32 bit processors r unning at up to 80 MHz It has shared global resources including 32 KB of RAM 32 KB of ROM and 32 I O pins It has dedicated resources per processor including 2 KB of RAM and two general counters and video output The Propeller operates at 3 3 VDC each pin can sink up to 40 mA It is available on Parallax s web site for 12 99 per chip and 29 99 per ProtoBoard ViewPort Parallax offers a free tool to load programs written in assembly or a high level language called Spin to the Pro peller This is fine for getting star ted writing simple pro grams but I quickly determined that I needed a more powerful debugging tool to develop and configure my vision powered balancing robot an application I now call ViewPort I started by dedicating one of the eight cogs to continu ously share data stored in the Propeller
150. y any of the demos via push button selections after you press the Power button However to get the Create basic unit to do your bidding using the open interface com mands you need a serial link to something that can send these com mands via the link This can be done with a ter minal emulator e g RealTerm running on your favorite computer with a serial interface While running Real Term on your PC with the Create connected via the serial cable you can use your keyboard to Figure 2 This is how the example DRIVE C code handles the movement of Create I based my assembly code on this flowchart Do movement Motors forward Motors forward Turning Backing Left Turn counter clockwise Turn clockwise Not Backing Remaining distance lt 5 mm Play bump song Random angle Y Y Y Y Y Y Y Y N N N N N N N N Any bumper Turning clockwise Backing turning Not turning Return Motors forward Remain angle greater than 0 degrees Remain angle less than 0 degrees 2903002 bachiochi qxp 2 5 2009 12 46 PM Page 59 60 CIRCUIT CELLAR www circuitcellar com March 2009 Issue 224 USB port provides a programming tether to a PC The RESET button jump starts the Command Module If a USB cable is plugged in the microcontroller goes into Bootload mode to accept code via USB If RESET is pushed without the USB cable plugged in it w
151. y directory names can be limited to eight characters If your system can t meet these require ments you need to include suppor t for long file names The last major consideration is the requirement that the CF or George Martin gmm50 att net began his career in the aerospace industry in 1969 After five years at a real job he set out on his own and co founded a design and manufacturing firm www embedded designer com His designs typi cally include servo motion control graphical input and output data acquisition and remote control systems George is a charter member of the Ciarcia Design Works Team He s currently working on a mobile communications system that announces highway info He is also a nationally ranked revolver shooter ROJECT FILES To download code go to ftp ftp circuitcellar com pub Circuit_Cellar 2009 224 ESOURCES CompactFlash Association CF and CompactFlash Specification Revision 2 0 2003 Compu Phase Implementing FAT on CompactFlash cards SD MMC cards and USB sticks 2008 www compuphase com mbr_fat htm Microsoft Corp Microsoft Extensible Firmware Initiative FAT32 File Sys tem Specification 2000 C Quirke Understanding FAT http users iafrica com c cq cquirke fat htm M Samuels PIC a CompactFlash Card Circuit Cellar Online 127 2001 I Sham W Hue and P Rizun Portable FAT Library for MCU Applica tions Circuit Cellar 176 2005 Wikipedi

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