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1. The EDC 1000C color imager interfaces directly to an IBM PC AT or compatible and digitizes images into 8 bits each of red green and blue for storage in the PC s RAM The camera uses a frame transfer CCD image sensor to provide a resolution of 75 1 x 488 interlaced or 751x244 noninterlaced Notable features of the camera include no dead space between pixels computer controlled exposure time and data collection rates up to 1 6 MB second 3 to 5 frames second in live mode TIFF PCX and Targa file formats are supported The camera can be used with virtually any Super VGA card that supports VESA Video Electronics Standards Association BIOS extensions version 1 2 and resolutions of 800x600 or 640x480 with 16 bit color The EDC 1000C camera and software sell for 950 The EDC 1000HR camera 751 x 488 pixels sells for 850 and the EDC 1000 camera 192 x 330 pixels sells for 400 Electrim Corp Electronic Imaging P O Box 2074 Princeton NJ 08543 609 683 5546 Fax 609 683 5882 103 800 507 0049 PARADIGM LOCATE PARADIGM TDREM PARADIGM DEBUG Comprehensive software development tools for all Intel 80C186 and NEC V Series microprocessors e Borland C and Microsoft C C support e Choice of stand alone or in circuit emulator debugging e Unlimited toll free technical su
2. CONSTRUCTION AND TESTING Por MAS The prototype of my project was ie TT wirewrapped Almost any layout will 14 AUTO FEED 17 SELECT INPUT work as long as it is neat and ad equately bypassed A metal box is the ideal enclosure even for units built ON Figure 4 The parallel expander uses two flip flops to read in data 8 bits at a time The decoding circuit eventually insulating surfaces such as fiberglass sends sixteen input bits four at a time to the parallel port The Computer Applications Journal Issue 37 August 1993 39 Data Acquisition and Control Listing 1 Utility routines for the Parallel Expander are written as a Turbo Pascal 6 0 unit however the E z more Critical routines are done in assembler Complete code is available on the BBS Without Compromise PROCEDURE GETPORT LPTNUM WORD Programmable Scan amp Burst BEGIN RTD s Advanced Industrial Control A LPTNUM lt 1 OR LPTNUM gt 4 THEN LPTNUM 2 LPT2 IS DEFAULT e ae oe ee OUTPORT MEMW 0040 0008 2 LPTNUM 1 J stan ard ror genera purpose LPT1 THROUGH LPT4 PORTH S industrial amp laboratory applications LAT 0040 0008 0040 000E INPORT 0UTPORT 1 CTLPORT OUTPORT 2 END PROCEDURE READWORD VAR INW WORD VAR J WORD X BYTE INPUT BITS 7_ 543 _ FAST CODE WITHOUT LOOPS OUTPUT BITS 3210 BEGIN ASM x XOR AX AX MOV BX AX MOV CX 04 Set up registers N A RA MOV DX C
3. Figure 7 Another potential format puts all 0 bits on OnE Mas e data data tions Journal S 5 1 ELSE STEE f the ower track and allt bits on the upper TIMEOUT S S 0 DO ALL BITS LOOK FOR THE END CODE TI MEQUT F SAME THEN BAD END CODE EXT BIT REM SAVE THE BIT NO SWAP NECESSARY IF DIRECTION OK F T MID S Z 1 NEXT Z S T PRINT THE DETECTED DATA LOOK FOR MORE DURING NO CLOCK MARK RETURN IF TIMEOUT NOW READ DATA 430 ELSE RETURN WAIT FOR NO CLOCK IF END CODE DOES NOT MATCH WE MUST HAVE BAD DATA INDICATE IT TRY AGAIN THIS IS THE TIMEOUT ROUTINE STOP TIMING TIMER FLAG NDI CATE IT TIMEOUT rack accuracy Although twice as many bits Video Frame Grabber 495 Including Software with C Library gt e Half Slot Card for Compact Applications e are packed into this format as opposed to the clocked format the throughput is the same but now each bit is verified Similarly I ve posted code similar to that in Listing Ib to poll the PC s joystick port and display the received data bit sequence If the start code complemented data and end code are received as expected then a beep declares an accepted swipe On the most basic level this optical reader could be used to recog nize 1 of 65 535 different cards Proper recognition might energize a solenoid powered door lock or perform some other task designated by the card s code The r
4. Part 2 The SCSI Bus BYTE Mar 1990 p 291 Inside Macintosh Volume IV Addison Wesley Reading MA 1986 Mass Storage Handbook National Semiconductor 1989 MC68000 8 16 32 Bit Micropro cessor User s Manual Motorola 8th edition Prentice Hall Englewood Cliffs NJ NCR 5380 Family SCSI Protocol Controller Data Manual 1989 SOFTWARE Software for this article is avail able from the Circuit Calar BBS and on Software On Disk for this issue Please see the end of ConnecTime in this issue for downloading and ordering infor mation Listing 2 continued OVE OVE OVE OVE OVE OVE OVE OVE OVE OVE OVE OVE OVE Moves data fromthe SCSI bus into DO sThe last word last 2 bytes of DO will schange to reflect values of DO 07 on the SCSI lines Use Macsbug to step sthrough the list of MOVE 5 commands Changing the Bus data lines will cause the contents of DO to change DO is svisible in Macsbug DWWOwWoOwWawvowvwnowwv cons I ce J es J ce cons con I wn ae ee a ee DOODO CO C gt rrPrrrrrr gt Yr gt UNLK result SCSI TestResult TestResult i switch result case noeErr printf SCSI noErr result n n gt aD brea default 407 Very Useful 408 Moderately Useful 409 Not Useful PROMJet Ultra Compact EPROM Emulator SOON Supporting Turbo Debugger CodeView HW Tracing and Brkpnts 2nd MB FREE Emulates 64
5. The Computer Applications Journal Figure 2 Depending on component selection a simple amplifier circuit can be made to behave differently A modeling program such as PSpice makes experimenting with values easy still be stable For typical applications when the phase shift of the feedback exceeds 180 the circuit gain should be 12 dB or less During the design stage of a project you usually want to determine a circuit s stability A theoretically stable circuit may oscillate when breadboarded which typically means there is a layout error Some op amps will oscillate with capacitive loads but will still show theoretical stabil ity Understanding the theoretical performance of a circuit may save you days at the workbench There are many ways to determine circuit stability Derive a couple of thousand phasor diagrams each at a different frequency to determine gain and phase relationships at each frequency While this is a thorough approach it is tedious and it s posssible you may miss the frequency range where a problem exists Bode plots can be used to judgea circuit s stability Plot both the open loop gain of the amplifier and the feedback network s response on the same Bode plot The slope change from one plot to the other at the point of intersection must be less than 12 dB per octave for absolute stability A polezero response can also be performed If all the poles of the frequency response l
6. U3 78Les battery centers on the ability to monitor the incoming and outgoing currents by using a small value sense resistor in series with one of the battery leads The absolute battery voltage must also be monitored in i IN QUT order to determine the point at which rach g T 10uF DS 1N4148 the battery goes empty Essentially YHIBIT the method integrates current over RL 04 oak 1N4148 353 ae time and meters the charge using a 3 asus counter When the battery discharges _ R2 8 05k through the sense resistor the result 93 soo ing voltage is monitored by the gas gauge circuitry and a counter is clocked in accordance with the current R3 30 1k RG Mete 4 drain Likewise during charging the current time product is integrated as charge is added to the battery This would seem to indicate that this measurement method could be used to Figure 5 Charging circuits that provide currents ranging from 3 to 9 amps usually require the use of an n channel power stage be a difficult proposition The first thing you need in order to arrive at the battery capacity is the full to empty value Full charge is the point of cutoff at which the charger terminates fast charge The empty level is the end of discharge voltage that is used as the reference for sh
7. rather than a plain old PC like the one they gave their kid for Christ mas Of course nothing s more PC compatible than a PC itself If you especially need or want to use PC add on boards and are willing to pay for easier upgrades and mainte nance consider the Passive Back plane approach Particularly if a CRT and or disk isn t part of the picture you can configure a hardened system with beyond desktop temperature and vibration tolerance Naturally this approach is also fully PC compatible since it involves little more than making the CPU board a plugger rather than a pluggee If you need full PC software compatibility in a smaller and or more rugged form factor consider one of the many Alt Bus alternatives Choose a standard bus such as STD 32 or PC 104 if you need a broad variety of I O add ons from multiple suppliers Or go with a particular company s proprietary bus if it s an ideal match for your application If you really just want to use PC development tools and find the above Photo 5a The Micromint RTC V25 combines the NEC 8088 likeV25 CPU with 32 parallel O lines an d channel ADC battery backed real time clock calendar 128 bytes of EEPROM two serial ports and a mix of up to 384K RAM or ROM Hard Core System Software Core components of your next 80x86 embedded design that is Embedded BIOS Embedded DOS CodeProbe New Our royalty free The 1 D
8. CMOS RAMs require CE within ZOOMY of Veco during backup to enter power down mode Use HCT or HCTLS gates on CE do not use C HC or LS Uco for the CE gate must come from Backup Voc u31 Mom Addr 4HCT32 Match m gt Bus Controls c gt Misc Controls lt gt Amber R54 i A 330 Ovce 021 178 LS245 ON Write Enabled Backup Vcc J Figure Adding a RAM tothe Firmware Development card uses circuitry similar fo that presented last month The two HCT32 gafes control the Chip Enable and Wife Enable pins fo prevent data loss during power loss The CE pin must be driven by a CMOS gate powered from the backup battery to ensure that the RAM enters standby mode the various pinouts My board sprouted five jumper blocks to handle these options but you won t need them if you pick just one chip and stick with it used an Hitachi HM622 56LP 150 RAM but as you saw in last month s column 8 bit ISA bus accesses allow more than 500 ns from the start of the SMEMR or SMEMW pulse If you plan to use a backup battery make sure the RAM is rated for low power standby operation which is typically shown by an L or LP part number suffix Unlike EPROMs and EEPROMs static RAM chips require continuous power to maintain their data Normal operation is specified at 5 volts but they will retain data down to about 2 0 volts as long as you don t try to read or 8K RAM nic 32K RAM At4 8K
9. FIRMWARE FURNACE Ed Nisley ower tends to corrupt and absolute power corrupts absolutely While Lord Acton surely didn t consider firmware back in 1887 his epigram applies to our task this month Putting vital data in RAM requires absolute control of both the power supply and the code but preventing data corruption is what it s all about Adding a RAM chip to the Firmware Development Board is easy but protecting it from harm is some what more difficult You ll find the power monitoring and watchdog functions helpful even if your project doesn t need a battery backed RAM PREPARE TO RAM The new hardware this month has three main sections the static RAM chip with its support chips a Maxim MAX691 Microprocessor Supervisory Circuit and a 16 bit I O port Refer back to the previous columns in this series for the complete schematics as there s just not enough room to reprint everything every time Figure 1 shows the RAM and its support circuitry which is quite similar to the EJEPROM hardware earlier in this project As promised we now have firmware controlled write protection with an LED to indicate when writes are enabled The Firmware Development Board s memory socket can hold RAM EPROM or EEPROM memory in either 8K or 32K byte sizes The chips were designed with compatibility in mind but Figure 2 shows the connec tions needed to adapt a single socket to Bus Address C gt CAUTION
10. The bypass cap must store enough the bits faster than the eye can follow if counts interrupts and sends one bit every WATCH_RATE ticks The energy to stabilize the voltage during mainline code mustreset the WatchPending flag at least once every 16 bits to prevent this code from forcing the huge current spike shown in Figure a watchdog reset 3 You should also bypass the static RAM at its socket as transient HandlerWDO 1 currents are offended by long wires With power assured the next step asm i is controlling the CPU during the j PUSH AX Save bystanders switch over After all it does no good PUSH DX to preserve data scrambled by a power PUSH DS starved processor OV AX CS aim at our segment again OV DS AX DATADEFENSE Count down the interrupts until we need a watchdog update The Original IBM PC power supply produced a Power Good DEC lt WatchDivide signal that held the CPU in reset until NZ WD Ret OV lt WatchDivide WATCH_RATE all of the power supply voltages were stable When you flipped the Big Red Decide if a new watchdog word is needed Switch the Power Good signal If it is and the mainline code is jammed we lock up and die dropped before the supply voltages a mae A ie 9 WD Tick DEC gt WatchCounter al ecean pS Syren a Way S Saw INZ WD Go nonzero says use old bits dean power when it was running CMP gt WatchPending 0 has mainline code reloaded bits The ISA bus RstDrv Reset E D_load zero says yes so we a
11. classify them into the following groups PC In A Box Factory floor enclosures for standard desktop PCS Passive Backplane PC bus typically ISA plug in CPU boards Alt Bus Passive backplane or mezzanine non PC bus boards Almost PC PC developable but not PC compatible Read on to compare and contrast the strengths and weaknesses of each flavor Photo 2b The Advantech PCA 6146 processor board includes a 486DX up to 16M of DRAM 256K of cache DE and floppy interfaces serial and printer ports battery backed real time clock and watchdog timer PC IN A BOX Once visiting the factory floor of an industrial concern watched as a maintenance technician approached an imposing and rather expensive looking control system packaged in a jukebox sized rack As the technician prepared to open the access paned expected to see some fancy electronics Imagine my surprise when spied resting on the floor of the cavernous and otherwise empty bay a noname PC clone You can give your PC a big iron makeover The Computer Applications Journal without needing a machine shop For instance Industrial Computer Source offers the 6200 UMR rack mount packaging system Photo 1 that accommodates small footprint PCs keyboards and desktop monitors The PC In A Box approach has the advantage of minimizing the cost of the PC portion After all no alterna tive implementation of the PC can ma
12. cube obt 950 name cubel translation 0 0 The keyword name indicates that a new object is being defined This is followed by the virtual word for this object which in turn is followed by the filename for the object The transl ation keyword tals the renderer to place the first cube at the coordinate position 0 0 950 The second cube is defined as name cube2 cube obt translation 100 0 100 The last line for this joint file actually creates the joint joint cubel cube2 This line creates a joint between the objects cubel and cube2 The object cube 2 is a descendant of the object cube 1 Thus any movements or rotations performed on cu b e 1 will affect c u be 2 but movements on cube 2 will not affect cube 1 Joints work on a tree concept where actions fall down the tree but not up YOUR VIEWPOINT The position in which you view a virtual world makes a difference One of the exciting things about virtual reality is the ability to view a world from any viewpoint You can get call the first cube object cube 1 To set the root use the following VIEWPOINT view_one ROOT cubel if view_one printf The next part of the joint file defines all of the objects that will be EEE NEA EAA AAG We re Small We re Powerful And We re Cheaper MMT 188 EB 2serial Y O ports e 3 programmable parallel 1 0 orts 1Meg RAM ROM capable powerfail detect interrupt and reset
13. 10 STRIG O ON 20 STRIG 4 ON 30 T 0 40 S T 50 MER OFF 60 GOSUB 390 70 ON TIMER 1 GOSUB 470 80 TIMER ON 90 LG G X 0 100 GOSUB 390 110 IF T 1 THEN GOTO 30 REM RE RE RE RE 120 130 IF LG G GOTO 100 D G FOR X 1 TO 16 LG G THEN X X 1 ELSE RE REM REM RE RE 140 150 160 170 180 EM GO WAIT FOR F LG lt gt G AND X gt 1 THEN GOTO 160 X 0 ENABLE JOYSTICK BUTTON TIMEOUT FLAG CLEAR STRINGS SHUT OFF TIMER UNTIL WANTED A BUTTON OR TIMEOUT TO GO if TIMEOUT ONE HERE S WHERE START THE TI MER SAVE LAST BIT A GO WAIT AGAIN IF TIMEOUT THEN D INIT COUNT START OVER REM START BIT RECOGNI ZED RE F BIT THE SAME INCR SAVE THE BIT OTHER ENTI FieS DIRECTI On HE DATA BITS COUNT GET A LAST sIT OW FOR GET ONE GOSUB eT 190 200 210 22 THE T GOTO 30 RE RE 390 RE THEN GOTO 30 RE G THEN GOTO 440 RE 390 IRE THEN GOTO 30 lt gt G THEN GOTO 440 GOTO 30 HEN GOTO 440 GOTO 30 lt gt G THEN GOTO 440 PR D 0 THEN GOTO 370 RE FOR Z LEN S TO 1 PRINT S GOTO 30 WHILE STRIG 1 0 F T THEN RETURN WEND ABS STRIG 5 RE STRIG 1 1 THEN GOTO RE RE RE SRE TIMER OVERFLOW REM ER OFF RE 1 RE NT RE TURN RE RE RE RE BAD EXIT NT GOTO 30 start shes aaa 1 track i ail 0 track
14. 128 bytes of EEPROM two serial ports and a mix of up to 384K RAM or ROM Roughly the same size as aPC 104 card the RTC V25 also has a stackable though proprietary bus for I O expansion As for add on boards there s nary a VGA IDE or game port to be found Instead there are control oriented expansion boards such as TTL buffered and optoiso lated I O 12 bit ADC LCD infrared and so forth Issue 37 August 1993 65 The Mini Cl86 Photo 5b flaunts its difference from the pack with its nickname as the No Bus No Fuss computer It combines a 186 with three 16 bit timers two serial ports watchdog timer power fail detect program accessible DIP switch and LEDs and up to 512K each of EPROM and SRAM Despite the No Bus moniker it also includes two iSBX connectors for modules adhering to that Intel defined I O add on standard PICK A PECK OF PCs Understanding the merits of each category of PC makes choosing the right alternative a little easier The particular need for a disk and or CRT is a vote in favor of the PC In A Box strategy because you can take advantage of the competition in the desktop market and get a really low price Since the disk and or CRT dictate a fairly benign environment the fact a desktop PC isn t that rugged is moot Frankly this approach is also suitable in cases where the customer will be happier paying the bill if they perceive they are getting a hunk of iron
15. Albert Einstein See Sidelights of Relativity by Albert Einstein London 1922 p 23 Zero crossing detection Msg 11433 From GREG PRICE To ALL USERS Any ideas out there on a simple circuit to detect the zero crossing point of the AC signal so can switch a nonlatching relay on and keep it on until a control signal 8255 buffered goes low Thought about an AND gate with a flip flop or a PAL am sure this has been done many times and many ways Any help would be appreciated Msg 11877 From J OHN CONDE To GREG PRICE Wel the easiest way know of to detect the zero cross would be with a zero crossing detector chip 3059 3079 if memory serves This will output a pulse when the signal crosses zero in either direction The pulse can gate an SCR which will keep your relay on Turning it off is another problem The simplest would be to have the control signal supply the current to the rday through the SCR then when the signal went low the SCR would turn off and the relay would drop out Of course if the control signal can t supply enough current you can have it control a transistor that will Hope this helps Msg 11889 From PELLERVO KASKINEN To GREG PRICE First get a zero crossing signal as a narrow pulse Then feed it into the clock input of a D latch or make one out of 86 Issue 37August 1993 The Computer Applications Journal a pair of 3 input NAND gates One input on each for data a second one
16. Call for details PIR Motion Detector poets for two or more 243 Selectable pulse count Area coverage 90 wide angle up to 40 feet Very reliable 9 16VDC 17mA Prices and UPS offers are for a limited time onty amp subject to change without notice E1208G6 Issue 37 August 1993 55 Take a Swipe at Optical ID Cards Stuck on how to come up with a data input system for identification purposes or logging data Using off the shelf components and your PC s joystick port Jeff builds an innovative bar code reader 56 Issue 37 August 1993 FROM THE BENCH Jeff Bachiochi an you guess how many different cleaning agents are for sale at the average supermarket Today counted 35 brands Of those 25 were available in a pump and 10 in an aerosol They range in color from the deepest blue to the most fluorescent orange Most will dean blueberry stains without scratch ing your precious porcelain surfaces Manufacturers seem to spend more money on packaging and adver tising than on the actual product Products today aren t good enough if they just dean They must also kill bacteria be gentle and leave a pleas ant scent behind But none of these products can eliminate the unpleasant task of data entry SWIPE TO THE RESCUE Supervisors and employees agree task management has never been much fun However it is critical to the ORCUIT CELLAR DOSE EAA THE COMPUTER
17. EMU for short Not only incorporating a complete fast charging system that includes continuous charging pulse charging burp charging and program mable pulsed trickle charging func tionality along with the usual primary and fail safe charge termination options the bq2001 also contains a gas gauge nonvolatile lithium based RAM using an external cell and a serial microprocessor interface The bq2001 is EEPROM based and allows the programming of default opera tional parameters in order to allow it to operate in a stand alone fashion without the need for any processor intervention Also included on chip are a bunch of dedicated and program mable output pins that can be used for control status or as general purpose outputs along with a backup cell output for powering external nonvola tile RAMs RTCs or other low level loads A built in charge pump serves as a voltage doubler that allows the use of an n channel FET as the charge control power switch A control function is provided to drive a p channel FET that would be used to control battery power to the system That s what it has How it works is another matter entirely frankly this thing is a challenge to understand What s most amazing is that this part is now a few years old Keep in mind that when it was originally developed there was nothing quite like it and there still isn t This thing is destined to become a classic 76 Issue 37 August 1993 C
18. IDE and floppy interface two serial ports one printer port battery backed RTC and even a1 5 15 150 second select able watchdog timer At the other extreme consider the MBPC 640 Photo 2c which thanks to the ever shrinking VLSI can actually handle significant applications with a measly three half size slots Use one slot for the PCA 6134 33 386SX CPU card and you ve got two left for your applications unique I O needs ALT BUS PCs This refers to systems that offer complete PC software and functional compatibility but are based on a non PC bus Of course most of the differ entiation depends on the characteris tics of the particular bus used You can choose a standard bus such as VME STD 32 or the new PC 104 all of which offer multivendor mix and match capability This is especially useful if you must interface to existing boards or systems that use a particular bus Photo 3b A typical PC 104 stack from Ampro consists of a 286 CPU board an Ethernet interface and a GA controller 64 Issue 37 August 1993 The STD 32 bus is a dever 32 bit upgrade of the old standby 8 bit STD bus Unlike the ISA bus which differentiates 8 bit and 16 bit slots with an extra connector STD 32 interleaves the new 32 bit signals with the old 8 bit signals This allows flexible setup including a 32 bit CPU in an 8 bit bus an 8 bit I O board ona 32 bit bus and of course a full 32 bit configuration A key
19. M9N 3K9 Canada 416 245 2953 Fax 416 245 6505 PC 104 and Eurocard CPU and T O boards Mesa Electronics 1329D 61st St Emeryville CA 94608 510 547 0837 CPU board combined with CGA backlit LCD Advanced Interface Board for Macintosh LC LCI LCM and Performa 400 Analog 8 software selectable analog inputs 12 bit ADC 8 microsecond conv time 5 software selectable input ranges One 8 bit DA 3v to 3v Digital Two 8 bit ports for digital T O Timer 24 bit programmable timer Software Available Sunset lab Computer Interface 49 95 Ageneral purpose Macintosh based data collection analysis package Sunset Laboratory 2017 19th Ave Forest Grove OR 97116 503 357 5151 138 The Computer Applications ournal Micromint Inc 4 Park St Vernon CT 06066 203 871 6170 Fax 203 872 2204 3 5 x 5 V25 based SBC Micro Aide 685 Arrow Grand Cir Covina CA 9 1722 818 915 5502 STD bus V40 and 386SX based SBCs Micro Alliance Inc 449 Santa Fe Dr Ste 800 Encinitas CA 92024 619 942 9800 Passive backplane CPUs I O boards and packaging Micro Link 401 Pennsylvania Pkwy Ste 205 Indianapolis IN 46280 800 428 6155 Eurocard VME and STD format PC and I O boards BCC72 BASIC 72 Computer Controller Micro Sys 3447 Ocean View Blvd Glendale CA 91208 818 244 4600 STD bus 386 and 486 DOS compatible SBCs Mu
20. Maxim obviously took some hits on this as they now havea MAX691A with a far more useful 10 ns nominal delay The key is to control a faster logic gate with a DC signal As shown in Figures 1 and 4 if CE In is grounded the HCT32 gate delays the RAM chip vec RSI SET 40mU ABOVE TRIP POINT 5U GIVES 4 85U TRIP 1 4U 45k 100k 82k select by only about 20 ns When CE Out goes high the RAM is in standby mode with its CE pin driven nearly to the supply voltage by the CMOS gate Obviously the external gate must be powered by the backup battery through the MAX69 1 You should use an HCT gate rather than C or HC to ensure that the inputs respond to TTL switching levels Pure CMOS gates have V thresholds well above the normal TTL V level and may not work correctly when driven by TTL gates PROCESSOR PROTECTION Although the data in RAM is now safe from harm It would Be Nice if the CPU knew what was going on too After all simply disabling the RAM may cause invalid data if the CPU was in the midst of a multibyte update Although the power may be failing a millisecond gives you a lot of time to put things in order The MAX69 1 can provide an early warning of impending doom by BETTER IDEA MONITOR THE RAW DC RSO 2 5k BATTERY CAPACITY DEPENDS ON RAM CURRENT AND DESIRED MEMORY BACKUP TIME I0 DECODES OSC SEL INPUT LOW BLINKING WATCHDOG monitoring the voltage on its Power Fail Input pin whe
21. Of course even with insane discounting some low end applications don t need the expandability and can t afford the overhead associated with a PC However with ever falling prices it s more and more likely an embedded PC is in your future For instance any situation that calls for a disk or CRT is likely well served by an embedded PC Why rein vent the wheel when you can toddle over to your local PC To Go empo rium and pick up aVGA monitor or a hard disk for a song In fact the advan tage extends to nearly any mass stor age floppy CD ROM tape and dis play CRT LCD plasma technology Potential trouble spots are applications that demand speedy real time response or a large linear address space Actually the performance limits are mainly a function of software like BIOS DOS and Win dows and can be overcome to some degree by writing or buying different software However feel that compat ibility with PC development tools is a major advantage and when it is lost the embedded PC approach starts to make less sense As this by no means exhaustive buyers guide indicates there is a Photo The Industrial Computer Source 6200 UMR rack mount packaging system Photo 2a The PC 616 from Advantech includes a 16 slot motherboard and a 250 W power supply in ifs 19 rack mount chassis bewildering array of products that fall under the heading of embedded PC To help make sense of it all
22. The geometry file is where the actual polygon is defined It is essen tially the same as the PLG file de scribed above except the color infor mation is in the header file Figure 3b shows an example of a geometry file for a simple cube Once an object has been defined in the OFF format it is converted to the PCVR Renderer using a conversion program called LOADOFF EXE Once all of the object files have been created the rendering package has the ability to create joints between them The classic example of a series of joints is the human hand The developer of a virtual world wants to see a hand in a program so the user can grab things In order to moda the hand correctly the devel oper creates a palm object and objects for each of the finger and thumb segments Using the 0 NTS file the developer creates joints between the palm and the first segment in each of name description author copyright type usually for Property list ii Prop this object data type POLYGON format filename or default data geometry vertex order polygon_colors back faces i ndexed_pol y default default default fff filename geom s clockwise fff 1 0 1 0 1 0 s cull Figure 6 fhe popular OFF format uses a pair of files to create an object and include the geometry file and the header file shown above the fingers and the thumb The developer further creates joints for each of the segments in the hand Joint
23. and timeouts as a Figure 7 shows an alternate format that uses the bottom track as data 0 bits and the upper track as 1 bits In this format both tracks are watched and data is assembled as the marks are reached in a self clocking format Unlike the previous clocked format this requires fewer character spaces per bit we re dealing with edges now DATA INTEGRITY The fact that data of a fixed length is Surrounded by proper start and end codes ensures data integrity to a high degree Additional steps can be taken to increase data integrity You might want to add a simple CRC integrity bit or complement every bit of data The tradeoff here is the maximum number of character places which will fit on a card I ve posted code on the BBS similar to that in Listing la to print a self clocking format that uses comple mented data bits to assure high Figure 6 The width of data data marks must be three times as l 0 wide as the clock marks to data track ALAIA porno assure reliable scanning in either clock track SBME gehegiaal pS direction T23 1 2 3 bit width Listing 1 a Very low density bar codes can be printed using standard BM character graphics 10 REM LOWER TRACK IS CLOCK UPPER IS DATA 20 H CHR 219 CHR 221 RE 30 L CHR 32 CHR 32 RE 40 C CHR 222 CHR 32 RE 50 FOR C 1 TO 24 RE 60 CLK CLK C 70 NEXT C 80 INPUT Enter a number 0 65535 X 90 X O INT X
24. channels such that if for example the signal coming from the right is louder than that coming from the left the output of the logic unit of the right channel will be enabled and the corresponding indicator activated indicating the sound source on the right An indication of the loudness is also provided One embodiment of the invention may be carried by the hearing impaired or deaf as a system for example which is embedded into eye glasses or a cap Another embodiment of the invention may be integrated with a vehicle to give a hearing impaired or deaf driver a warning with a directional indication that an emergency vehicle is in the vicinity In this second embodi ment the emergency vehicle transmits an RF signal which would be used as an enabling signal for the visual aid device to avoid false alarms from traffic and other sound sources in the vicinity of the drivers vehicle 4 982 432 1991 01 01 Clark Graeme M Blarney Peter J AUX University of Melbourne 2 150 364 3 612 061 3 831 296 4 390 756 4 441 202 4 581 491 Electrotactile vocoder An electrotactile vocoder for persons having impaired hearing in which electrical stimulation is applied to a multiplicity of electrodes in contact with either side of each finger so as to electrically stimulate the digital nerves of the user under the control of stimulator circuitry which is in turn controlled by processing circuitry for a speech signal received by a directional microphone worn o
25. i ee get Sh a supports up to 36 COM ports DigiBoard and Hostess boards full support of NS16550 UART chip supports math coprocessor and emulator e fast inter network communication using Novell s IPX services runs under MS DOS 3 0 t06 0 DR DOS LANs or without operating system perform DOS calls from severaltasks without re entrance problems supports resident multi tasking applications TSRs runs Windows or DOS Extenders as atask supports CodeViewand Turbo Debugger ROMable full source code available norun time royalties OnTime MARKETINGA Professional Programming Tools Karolinenstrasse 32 20357 Hamburg Germany Phone 49 40 43 74 72 Fax 49 40 43 5196 CompuServe 100140 633 The Computer Applications Journal Issue 37 August 1993 75 of this risk most fast charge ICs don t make use of this capability as a means of charge termination Refer to the manufacturer s data sheets to get the general idea behind the capacity gauging algorithm used by the bq2010 gas gauge IC Since you won t be able to get silicon for several months won t go into any further details on this IC at this time ALL BUT THE KITCHEN SINK Now l Il briefly touch on a battery management IC that is so complex that won t even attempt to give you more than an overview of its func tional capabilities This fiendishly complex peripheral is called the bq2001 energy management unit
26. of Abstract 8 from the University of Melbourne begs further study of the full patent It appears that the device permits the user to receive The Computer Applications Journal KANNEN TALK Patent Number Issue Date Inventor s Assignee b US References Title Abstract Patent Number Issue Date Inventor s State Country Assignee US References Title Abstract 5 029 216 1991 07 02 Jhabvala Murzban D Lin Hung C The United States of America as represented by the Administrator of the National Aeronautics amp Space Administration 3 568 144 3 626 365 3 927 388 4 212 085 4 712 244 4 794 394 Visual aid for the hearing impaired A multichannel electronic visual aid device which is able to signal to the user whether sound is coming from the left or right front or back or both For the plurality of channels which may operate in pairs the sound is picked up by a respective microphone and amplified and rectified into a DC voltage The DC voltage is next fed to an analog to digital converter and then to a digital encoder The binary code from the encoder is coupled into a logic circuit where the binary code is decoded to provide a plurality of output levels which are used to drive an indicator which in turn provides a visual indication of the sound level received The binary codes for each pair of channels are also fed into a digital comparator The output of the comparator is used to enable the logic circuits of the two
27. to the interrupt The code examines the MAX69 l s PFO bit through port 3 1C if it s zero a power failure is impending Other wise the code simply invokes the previous handler set up by the BIOS during the power on sequence Because further interrupts are blocked out until the CPU executes an CIRCUIT CELLAR PROJ ECT FILE RET instruction the tight loop at NM T_Loc k could be replaced with a H 1 t I favor a loop sol can add a few instructions to toggle an output bit that flags the event on a scope but the choice is yours RELEASE NOTES The code on the BBS this month includes C and BIN files for RAMT E ST and DOGTEST Remember to boot DOGTEST directly from diskette so it gets control before the MAX691 resets the system I ve also tweaked the LOADEXT ASM routines from last month You can now load a BIOS extension from diskette into either EEPROM or RAM and set the checksum on the fly OK that s enough hardware If you can t start doing embedded PC code with what we ve got now it s time to dust off your COBOL manuals Next month plan to spend some time exploring BIOS extensions hardware and firmware resets and the worst hack in PC dom x SPECIAL SUBSCRIBER OFFER y GET BOTH VOLUMES I amp Il P FOR ONLY 29 95 For a limited time only TOP projects from the Circuit Cellar Design Contest NEW projets amp tutorials Something for every interest O
28. 149 from the University of Virginia Patent Number Issue Date 5 157 759 1992 10 20 Inventor s Assignee Bachenko Joan C AT amp T Bell Laboratories US References 5 060 154 Title Written language parser system Abstract 78 Issue 37 August 1993 The Computer Applications Journal NEMEN TALK srs presents a system for detecting eye movement and for determining the direction in which the viewer is looking Based on an IR LED and IR sensitive TV camera arrange ment the system homes in on the bright eye effect of light reflected off the eye Special processing of the signal promises to yield rapid response and highly accurate resolution As mentioned in the abstract such a device serves handicapped persons and also has applications in cockpit and industrial settings Abstract 3 presents a pneumatically controlled switch interface It offers the handicapped person a means of interacting with their computer and other electronic devices Conventional commercially available software may continue to be used on the computer since the device simulates existing input devices One might envision other nonhandicapped uses for such a pneumatic input device in explosive or otherwise electrically hazardous areas Abstract 4 represents two patents by Adam Jorgensen 4 907 136 and 5 107 467 which present an ultrasonic apparatus for giving the visually impaired user more knowledge of his surroundings and for aiding him in navi
29. 19 21 0x17FF 3 25 17 19 0x17FF 3 25 15 17 0x17FF 3 25 13 15 0x12AA 42310 0x12AA 44532 0x12AA 46754 0x12AA 48976 0x12AA 4 101198 0x12AA 4011110 sides oftrunk 0x17FF61357911 bot of trunk Figure5 Public domain objects such as a tree are plentiful and often save you from reinventing the wheel be anywhere in the three dimensional coordinate system Are you going to be under the park or above it The last consideration is the presentation of the images Is any special hardware being used If so you may choose a stereoscopic presenta tion In the next three sections will address each of these areas OBJECTS AND J OINTS The PCVR Renderer includes the ability to create any object such as the tree discussed earlier The renderer itself includes a format that allows very precise handling of objects that can be confusing for beginning pro grammers Therefore recommend building objects using the OFF format This format allows for the creation of objects that can be used in a variety of other software packages and is freely transferable in public domain The format is defined by the creation of two files called the geometry file geom and the header file aof f The header file includes the informa tion shown in Figure 6 The information in the property list is standard except for the color of the object which is described in the common red green blue format A value of 1 0 is full color intensity
30. 4 Read Only Bus and Status Register BSR Bit 7 Bit 0 EDMA DRQ SPER BSY ATN ACK 8 Bits Hex Addr 5 Read Only Only three of them are necessary for very basic experimentation 28 Issue 37 August 1993 The Computer Applications Journal puter by the machine s internal SCSI controller chip To become familiar with the operations of this chip it is best to experiment with it while it is in this no holds barred breadboard setup From the peripheral side of the 5380 the correct pins must be set to place data on the SCSI bus FOR EXAMPLE Now I ll present a specific example of how to set the registers to allow data to be written out to the SCSI bus Like any project combining software and hardware the board must be initialized to a known state before anything predictable and useful can happen which means all of the control signal and data lines should be set to their floating or off states The DIP switches should be set so that all of the bus lines are floating at 3 33 volts all should be open The data and control lines need to be set to their inactive state which means the DIP switches for those need to be closed The switches that control the address lines AO Al and A2 should also be closed The DIP switches covering WR RESET E0P DACK RD and CS should be left open Finally READY INT and DRQ should be switched to ground Once the 5380 is set in it
31. CONLIN To MICHAEL SWARTZENDRUBER The plastic case may be causing my problem was under the impression that shielding all wires and placing the system six or so feet from the magneto could be enough am going to place the board in a grounded case However this is not a vehicle that can be started unless it is at the drag strip With a limited number of passes per season would like some suggestions on how to ground the GERMANY NEW POSTAL CODE Don t delay You won t want to miss a single issue system Should have a separate electrical ground and then ground all shields and the case to the chassis Should the electrical ground be connected directly to the chassis or just capacitivly coupled To answer your question all ICs are tacked into their respective sockets to prevent everything from shaking apart The entire black box is also soft mounted Thanks for your input Msg 15204 From ALAN COOK To PAUL CONLIN First move MUST be to put it all on a proper PCB NO sockets Largest ground planes you can afford Plenty of suppression on the supply lines would decouple power and ground for the CPU and memory each memory chip using a balun 22 uF cap and 0 01 nF cap in parallel You might even want to try this across the ground for any output drivers Don t mount any caps vertically and epoxy large components in place where possible If you allow for these components on the PCB design you can always omit
32. MOVE B 0x08 AQ This move pulls the BSY gt line active low 32 Once the BSY bit has been set the Target Bit in the Mode Register must be pulled low This can be accomplished by the following code LEA SWrMR2 A3 A0 gt Set AQ to point to the Mode Register 2 MOVE 6 0x40 A0 Pull TARG bit low 3 Now the ICR which was used in step 1 above is again called and the DBUS bit bit zero must be set to allow sus to put data out on the SCSI bus So we must reset our Address in register AQ LEA sWrICR A3 A0 SetAO to point to the ICR MOVE B 0x01 A0 Pull DBUS bit low gt 4 We should now be able to write data out to the SCSI bus at s will by directing our hex data stream to the Output Data Register LEA SODR A3 A0 SetAO0 to point to the ICR OVE B 0xAA AO z Pull ODR bits low MOVE B 0xAA AO OVE B 0x55 OxAA A0 0x55 AQ OxAA A0 0x55 OxAA x55 xAA x55 A0 xAA xAA AQ AD AQ AQ A0 lt mmoam mmo osm mss mM msm ms Vvv vlw VVV YD W OXAA U A6 OVE esult SCSIReset TestResult TestResult J switch result t case noErr printf SCSI noErr resul t n n break default break The Computer Applications Journal 34 Listing 2 The code fo test the reading function simply does continuous reads of the bus allowing you to inspect each reading by single stepping
33. Motorola 680x0 683xx and 88000 MIPS and Sparc downloading and ordering infor mation Zb Hundred Acre Consulting FIRS sd Ne 5301 Longley Lane Suite D 144 Reno NY 89511 aie NEI SEN 800 245 2885 1 702 829 9700 417 Moderately Useful 418 Not Useful The Computer Applications Journal issue 37 August 1993 61 In Bed With PCS 62 Issue 37 August 1993 SILICON UPDATE Tom Cantrell h the IBM PC can t live with it can t live without it Yes I admit to a distinct love hate relationship with the PC On the one hand cut my micro teeth on the 86 family and having designed boards and written a lot of assembly code became intimate with its architecture quirks warts and all But it s those same quirks and warts that can get to you Starting with the in your face CISCiness of the CPU strange and singular oddities percolate up through the PC system design and surface in the OS and application software Nevertheless the PC s main virtue its low pricemakes up for myriad technical sins Indeed it s the incredible value of PCs that is driving the downsizing in the computing market The same forces are at work in the embedded arena SO MANY PCs SO LITTLE TIME Deciding if an embedded PC is right for you depends on whether certain key application characteristics match the strengths of the PC while The Computer Applications Journal avoiding its weaknesses
34. RS 232 interface Power requirements are only 180 mA at 5 volts and 16 67 MHz Sleep functions are included to conserve power The on board EPROM contains Motorola CPU32Bug with additional commands for loading the Flash memory directly from the serial port The combination of on board CPU32Bug and Flash memory speeds develop ment and adds greater flexibility when software modifications are required The S E C is suitable for data acquisition process control and other real time applications Software is devdoped and loaded directly into the on board Flash memory After the software has been fully tested a removable jumper allows the CPU to boot directly to the application code The SRAM may be Syndetix Inc 2820 North Telshor Blvd Las Curses NM 88001 505 522 8762 Fax 505 521 1619 505 8 Issue 37 August 1993 The Computer Applications ournal AAA SOD CLOSE NEWS ELECTRONIC COLOR IMAGER Digitized 24 bit color images with a resolution of 75 1 x 488 pixels can be accomplished with a new high resolution color camera from Electrim Corp Applica tions for the device include desktop publishing machine vision document imaging security industrial inspec tion and telecommunications
35. The PC Parallel Expander plugs into any standard PC printer port and provides 16 inputs and 16 outputs with a bit of coding voodoo thrown in to make the whole thing work On the Mac side Marc Bumble covers the basics of putting together a rudimentary Mac SCSI interface that can be expanded into any number of applications Another prime example of user input driving a response is the up and coming world of virtual reality By definition a VR system generates a display and sometimes physical motion based on a user s body move ments While the subject of VR can fill volumes we get you started with a discussion of the basics of virtual reality and how you can get started with VR using your desktop PC On a much smaller scale the idea of feedback affecting the final output almost always shows up in amplifier design Our fourth feature article shows you how to use computer based simulation to ensure your latest amplifier design is stable across its range of operation In the regular departments Ed continues with the hardware enhance ments to his embedded 386SX by adding a watchdog J eff starts a two part series exploring an interesting cross between product bar codes and magnetically encoded credit cards optical ID cards Speaking of embedded PCs Tom presents an overview of the present embedded PC marketplace and gives you plenty of resources to investigate J ohn concludes his pair of articles on battery supervision and charging
36. and NMOS Use the highest allowable working voltage to increase the noise margins Minimize the amount of logic the number of chips and the lengths of the interconnects Heavy power and ground planes improve noise immunity by improving common mode noise rejection Watch out for devices that may be especially suscep tible to EMI RFI problems struggled with the TI TL7705 as best recall the part number It is a 5 volt supply monitor and reset generator had perfectly good working prototypes wire wrapped which did not use the TL7705 whose design then changed in what seemed to be a fairly innocuous manner The TL7705 was added to the produc tion design and put to PCB without prototyping the prototypes went from my screen to the road with hardly a hitch Turns out that the internal voltage reference circuit 88 Issue 37 August1993 The Computer Applications Journal design which is used in many different TI chips is particu larly sensitive to RFI at around 500 MHz didn t learn the exact nature of this problem until it turned up in a different product with a different chip that was failing when a handheld radio was keyed to transmit nearby Naturally the failure only occurs when the engine was running at high power when EMF emissions are at their maximum The symptom is a unit that resets itself more or less often while operating The biggest problem had in terms of the harshness of the environment were the
37. and is found by solving the following equation Cl L j 2r Unity Gain Cut off Frequency The maximum and minimum values of G1 can be limited to model the op amp s slew rate The classic capacitor equation is remy d i Cx T rr HANGS FORHARDWARE OR SOFTWARE REASONS PHONE TURN ON PC WITH PHONE WAKEUP OR SHUTDOWN PC LATE NITE BACKUP MODEM The current i is the limiting value of G1 needed to properly model the op amp s slew rate Eourisa unity gain voltage controlled voltage source controlled by the voltage across R 1 Eour can be limited to model the op amp s output voltage saturation characteristics Four in combina tion with Rour sets the output drive and resis tance characteris tics of the op amp Rour iS found by using the op amp s output voltage swing specification and is in series with the load resistance so 8 CHAN ADC DATA AQUISITION SERVOCTL AUDIO 8 BIT RESOLUTION 22KHZ SAMPLE RATE SHARP CUTOFF ANTI ALIAS FILTER CREATE STEREOBLASTER VOC FILES 95 CHAN DAC VOICE MAIL MUSIC ALAAMS CTL VOLT 8 BIT RESOLUTION 44KHZ SAMPLE RATE PLAYS MONO STEREO BLASTER FILES 75 FUNCTIONS AS DIGITAL ATTENUATOR TOO MVS BOX85 5 YEAR LIMITED WARRANTY Goes PING USA 22 Issue 37 August 1993 The Computer Applications ournal AC STABILITY ANALYSIS Date Time run 01 01 80 04 01 28 Temperature 27 0 aaa kh en diss tetov
38. at least every 16 bit times to prevent a time out This means the maximum delay until a reset is 2 6 seconds to shift all the bits out plus 16 seconds after the last bit or 4 2 seconds overall The most soothing bit pattern is F FO 0 which produces a reassuring heartbeat with 1 3 seconds on and 13 seconds off AAAA produces an exciting 3 Hz blink while F140 sends a one long two shorts blink code that might indicate a particular failure or error condition you can do a surpris ing amount with 16 bits if you have to Note that 0000 is a perfectly valid albeit dull pattern that will not cause a watchdog timeout The interrupt handler forces a transition between each pair of bits so the watchdog sees a pulse every 165 ms regardless of the bit values If you look closely at the LED in a dark room you can see those 1 3 ys pulses Try it DOGTEST s main loop is quite simple it checks and resets W at Ch Pen ding so the interrupt handler remains happy copies the DIP switches into W atchBitSso you can experiment with different bit patterns and writes a counter value into the LED digits so you can see something happening Bit Function 7 1 System board parity check 6 1 IO channel check 5 1 Timer 2 output bit 4 3 2 0 Toggles with each RAM refresh 0 IO channel check enabled 0 System board parity check enabler 1 Speaker data enabled 1 Gate Timer 2 output to speaker Figure 6 A Non Maskable In
39. be undetectable if the code is run at full speed See the MacsBug Manual for instructions on how to single step through the code Issue 37 August 1993 31 The New Shape of Embedded PCs The amazing CMF8680 cpuModule is the first complete 100 PC compatible PC 104 single board computer measuring only 3 6 by 3 8 E 16 bit 14 MHz PC Chip E CGA LCD controller 2M DRAM ROM DOS kernel bootable 1 M solid state disk configuration EEPROM 16 bit IDE controller amp floppy interface PCMCIA interface E two RS 232 one RS 485 amp parallel port m XT keyboard amp speaker port watchdog timer E 5 volts only operation Designed for low power applications the CM F 8680 draws one watt of power which drops to 350 milliwatts in sleep mode 125 milliwatts in suspend mode Free utility software lets your application boot from ROM RTD also offers a complete line of PC 104 peripherals for expansion E 1 8 hard drive amp PCMCIA carriers M12 amp 14 bit data acquisition modules opto 22 amp digital I O modules E VGA CRT LCD interface For more information call write or fax us today Place your orde now and receive a CM 102 PCMCIA carrie module FREE IDI Real Time D evices Inc P O Box 906 State College PA 16804 814 234 8087 m Fax 814 234 5218 117 32 Issue 37 August 1993 Listing continued The Initiator Command Register is also referred to as the ICR
40. by looking at some potent chips that take the burden off the designer Finally Russ takes a look at patent abstracts that relate in some way to making life for the handicapped a little easier 1 2 Issue 37 August 1993 The Computer Applications ournal CIRCUIT CELLAR THE COMPUTER APPLICATIONS JOURNAL FOUNDER EDITORIAL DIRECTOR Steve Ciarcia PUBLISHER Daniel Rodrigues EDITOR IN CHIEF Ken Davidson PUBLISHER S ASSISTANT Susan McGill CIRCULATION COORDINATOR Rose Mansella TECHNICAL EDITOR Michael Swartzendruber CIRCULATION ASSISTANT Barbara Maleski ASSOCIATE EDITOR Robert Rojas CIRCULATION CONSULTANT Gregory Spitzfaden ENGINEERING STAFF Jeff Bachiochi amp Ed Nisley BUSINESS MANAGER Jeannette Walters WEST COAST EDITOR Tom Cantrell ADVERTISING COORDINATOR Dan Gorsky CONTRIBUTING EDITORS ohn Dybowski amp Russ Reiss EW PRODUCTS EDITOR Harv Weiner CIRCUIT CELLAR INK THE COMPUTER APPLICA TIONS JOURNAL ISSN0896 8985 s published monthly by Circuit Cellar Incorporated 4 Park Street Suite 20 Vernon CT 06066 203 875 2751 Second classpostagepaidat Vernon CT and additional offices One year 12 issues subscription rate U S A and pos sessions 21 95 Canada Mexico 31 95 all other coun tries 49 95 All subscription orders payable in U S funds only viainternational postal money order or check drawn on U S bank Directsubscription orders and subscription related questi
41. counter timers e watch dog timer e expansion connector e amn Only 191 Qty 100 ALSO AVAILABLE MMT Z180 MMT 196 MMT HC11 MMT EXP In fact you ll get the best product for about half the price If you re interested in getting the most out of your project put the most into it For the least amount of money Call us today for complete data sheets CPU options prices and availability Custom Work Welcome Call or fax for complete data sheets 2308 East Sixth Street Brookings SD 57006 Phone 605 697 8521 Fax 605 697 8109 MMM NNE T SIMI POO IM MM MO 110 Niro kek pp Mp AE IO IM IAI GH IGM PRIM oiai aiai iai PIII PO siat miai igt HM GIGI GM I WE RE Swati BUT W E RE POWERFUL HO DEE EEE OE PPP IAEA iaaa IIIA FOE PE aaa 18 Issue 37 August 1993 The Computer Applications our nal create viewpoint View creation Figure 9 At initialization time a vi ewpoi nt failed n exit 1 structure is setup ata default coordinate of 0 0 0 8051 Firmware Debugging Techniques 65 pages w 3 5 diskette Introduction to the 8051 Instruction Set 46 pages 8051 Instruction Reterence Card 8255 Cheat Sheet Reference Card Embedded 386SX Project Parts INK 33 34 35 LD273 dual IR LED bright wide beam UGN3503U Ratiometric linear Hall Effect sensor IR3C02A laser diode controller 5 for LTO22MC LN9705P laser R3C07 laser diode controller 5V for LTO22PD LN9765 laser PH302 fast IR
42. data and converts it into a picture such as the one shown in Figurel Using a variety of different object formats and files very creative worlds can be designed for a user with any text editing program that can generate ASCII output The rendering software must also drive the shutter glasses and the other input devices In the case of an input device the software must allow the user to interact with the virtual world in a realistic fashion The user should be able to pick up objects and rear range them in real time This interac tion gives the user a sense of immer sion in the world THE RENDERER The basic functionality of a renderer is the same for low cost renderers and high cost renderers Figure 2 shows the loop that a simple renderer performs In this section give a brief idea about what each of these steps entails Loop Get User Transform and Project Sort Objects Vertices Backface Removal Color Draw Endloop Figure 2 Renderers continuously repeaf the same basic set of steps in real time fo create fheir illusions GET USER INPUT During user input the computer program must provide a visual or auditory feedback to any number of user generated inputs The user could provide input to the computer through a keyboard or some other device Typically some sort of three dimen sional input device is preferred The computer program must determine how much movement has occurred since the last interacti
43. drop across the LM 317 U2 the blocking diode D6 and the current selection resistor R16 Adding these losses together the total figure comes to about 4 5V Add to this the number of cells times the maximum cell voltage to arrive at the minimum input voltage required to deliver current to the battery as it approaches full charge iS available for it SWITCHED CONSTANT CURRENT The bq2003 can be configured as a switched mode current driver that is much more efficient than a typical linear current source If the main power supply s current limitation or power limitation is a problem then a switching current source may be the only way to go Even if a hefty power Charge Discharge Fast Pending Optional Charging Top Off Optional DIS MOD buck configuration A L a CHG Status Output H 34 sec T E TEMP Status Output l l Battery discharged to 1 V nominal MOD external regulation Battery within temperature limits Charge initiated Battery outside temperature limits Figure 2 The bq2003 will automatically handle aif phases of a battery charge cycle and provides feedback to the user by flashing an LED at varying rates 72 Issue 37 August 1993 The Computer Applications Journal Photo 1 The bq2001 charge management C has so many features and options a complete development system supply is available the product packaging might not tolerate the heat buildup associated with
44. for BIOS and DOS solutions that offer the safety of BIOS and DOS in a high performance real time environment Call or fax for free information and a bootable product demo disk Tel 206 391 4285 Fax 206557 0736 BBS 206 557 4BBS P O Box 2571 Innovative real time system software since 1989 Redmond WA 98073 Copyright C 1993 General Sofware Inc Alt rights reserved General Software the GS logo Embedded DOS Embedded BIOS and CodeProbe are trademarks of General Software Inc 66 Issue 37 August 1993 The Computer Applications Journal 137 approaches offer a lot of stuff you don t need VGA floppy game port etc and not the stuff you want buffered or optoisolated I O ADC etc consider an Almost PC If you re lucky you ll find a board that s just what you need no more no less with the lowest cost size and power consump tion Q Tom Cantrell has been an engineer in Silicon Valley for more than ten years working on chip board and systems design and marketing He can be reached at 510 657 0264 or by fax at 510 657 5441 419 Very Useful 420 Moderately Useful 421 Not Useful Photo Sb The R L C Enterprises Mini Cl86 promotes no bus no fuss by packing everything onto a single board Embedded PC Roundup Advantech 750 East Arques Ave Sunnyvale CA 94086 408 245 6678 Fax 408 245 8268 Passive backplane CPUs I O boards and packaging Amdex 76 Treb
45. immedi ately after its Reset input goes inac tive so if NMI is stuck active the CPU cannot even run diagnostics to pinpoint the problem However it s not a good idea to leave NMI off all the time so BM s AT engineers picked a distressingly clever way to control it The MC1468 18A Real Time Clock has 64 bytes of nonvolatile RAM addressed by the value written to I O port 70 The clock ignores the two high order bits so the engineers added a latch to bit 7 that inhibits NMI simply write address 80 instead of 00 to mask the unmaskable Wish you d thought of something like that for your last project The latch holds the mask bit and there is additional circuitry to turn it on during a hardware reset It remains set until the BIOS writes an RTC address between 00 and 7F which happens only after the BIOS is sure everything is ready Thus a hot NMI won t disrupt normal system diagnos tics NMI can be activated by a variety of sources depending on exactly which AT or clone you have The two standard sources are the system board parity check hardware and the IOCHCK signal from the ISA bus These signals are controlled by bits in I O port 61 as shown in Figure 6 DOGTEST s NMI handler shown in Listing 2 is much like the interrupt handlers you ve seen before with one key exception Because the NMI does not pass through the external 8259 interrupt controller chips the handler must not send out an EOI in response
46. in the polygon The vertices are listed in O to n Lorder This description of the tree object file is specific to the PLG format PLG is the data format for the public domain R E N D3 86 Virtual Reality renderer There are many object file formats used throughout the world The PCVR Renderer can convert from the majority of these formats The next step is to build the virtual world 108 Journal CREATING THE WORLD Creating a virtual world is a simple matter of determining what objects you want in the world Will you have trees and a park bench or just trees After the objects have been placed in the world you must deter mine from what direction the user will look into the virtual world This is called the viewpoint Viewpoints can tree 26 25 0 100 10 0 0 0 10 1 9100 5 2 90 5 3 9100 5 4 9 0 5 5 0100 10 6 0 0 10 7 9 100 5 8 9 0 5 9 9100 5 10 9 0 5 11 28 100 30 12 28 100 30 13 28 150 60 14 28150 60 15 28 200 30 16 28 200 30 17 28200 30 18 28 200 30 19 28 150 60 20 28 150 60 21 28 100 30 22 28 100 30 23 65150 0 24 point 65 150 0 25 point Ox17FF 414151312 rect sides Ox17FF 4 16 17 15 14 0x17FF 4 18 19 17 16 0x17FF 4 20 21 19 18 0x17FF 4 22 23 21 20 0x17FF 4 24 25 23 22 0x17FF 3 24 14 12 0x17FF 3 24 16 14 0x17FF 3 24 18 16 0x17FF 3 24 20 18 0x17FF 3 24 22 20 0x17FF 3 24 12 22 pointy ends 0x17FF 3 25 23 13 0x17FF 3 25 21 23 0x17FF 3 25
47. keyDownMask amp event 2 SCSIGlobals point to the Command Register is set by the 5380 it or the BSY bit continued The Computer Applications Journal oO ON DMD OO FR WD L W Figure 7 The Mac puts the typically 50 pin SCSI interface on a standard 25 pin D type connector system operation can be verified by observing the LEDs on the breadboard The SCSI base address is stored in register A3 the SCSI Global Param eters address is moved into A4 then we begin the 5380 bit manipulations We start by setting AQ to point to ICR using an LEA Load Effective Address call Once the ICR address is estab lished the BSY line can be set active low through the fourth bit DB3 in the ICR Next the MR2 target bit is pulled low to set the chip in its target mode In target mode only the target mode bit and the ICR DBUS bit need to be set to place data onto the bus So the next function performed is to load the ICR address and set the DBUS bit which is bit 1 or DBO Once the DBUS bit is set to active low data can be moved out onto the SCSI bus Register A0 is set to point to ODR Then the code simply moves data into the ODR The MO VE B command moves bytes of data out onto the bus selected the patterns AA and 55 because they are viewed in binary as 10101010 01010101 AA 55 The patterns of alternating LEDs should be evident as you step through the code The patterns will blur and
48. s Turbo Debugger Remote Code View style source level debugger ROMable startup code brings CPU up from cold boot ROMable library in source code Flexible 80x86 Locator COMPLETE PACKAGE ONLY 495 30 DAY MONEY BACK GUARANTEE 107 N OLYMPIC SUITE 201 ARLINGTON WA 98223 206 435 8086 e FAX 206 435 0253 124 125 The Computer Applications Journal Issue 37 August 1993 41 special I O boards are available sometimes at very reasonable prices In the case of a laptop the answer is Listing 1 continued TEST AL 10 obvious you use what you have 3 Actually the thought of using a laptop AL 08 as a tiny control console is quite an BX AX intriguing idea In the case of larger o ae PCs the answer is not so simple The DX CTLPORT Parallel Expander provides more O 08 than the typical paralla 1 O card but a special card may operate faster or have more complete and immediately useful software On the other hand the Parallel Expander can be connected without taking anything apart to the many millions of existing PCs in just a few seconds Since the Parallel Expander doesn t do anything by itself applica tions are up to you but a quick glance at Figure 1 should cause quite a few ideas to spring to mind For example gt lt Do nibb e 31 gt lt gt lt L 1 SHR AL 1 SHR AL 1 L 190 BK re QrrrrrWvvlrwurdYd
49. signals an echo profile detector for generating an echo profile signal of each echo signal a delay circuit for adding variable delay to the echo profile signal wherein the variable delay in creases with the distance to the reflecting at a diminishing rate of increase The sound burst emitter is preferably arranged to emit a beam of sound bursts having a given beam angle that can be pointed in any direction 5 144 294 19920901 Alonzi Louis W Smith David C Burlak Gary J Mirowski Marion LDJ Industries Inc 2 255 055 3 495 213 3 922 685 3 973 200 4 225 953 4 253 083 4 495 495 4 598 272 4 660 022 4 754 266 4 935 907 4 961 575 4 998 095 Radio frequency message apparatus for aiding ambulatory travel of visually impaired persons A radio frequency message apparatus for aiding ambulatory travel by handicapped persons such as blind indi viduals The apparatus generally comprises a portable radio frequency transceiver and a stationary radio fre quency base transceiver unit The portable radio frequency transceiver is carried on the person of the handi capped individual and transmits a message request signal in response to manual activation of a transmit button thereon by the handicapped individual The message request signal is received by the base transceiver which causes the base transceiver to transmit a prerecorded message signal back to the portable transceiver unit in radio frequency form The message signal contains location identify
50. start on your DSP applications If you still don t know where to start Control Resources can quote on writing algorithms or designing custom hardware for your applica tion Call or write today for more information Control Resources 19042 San Jose Ave Unit S P O Box 8694 Rowland Heights CA 91748 818 912 5722 VOICE 818 854 1439 FAX The only 8051 52 BASIC compiler that is 100 BASIC 52 Compatible and has full floating point integer byte amp bit variables 114 The Computer Applications Joumal Listing 1 is the PSpice input file for Figure 2 The subcircuit for the LM C660 was made using the tech niques defined above The AC voltage source VA isinserted into the circuit to perform the stability analysis The analysis is performed by sweeping VA from 1 MHz to 10 MHz The ampli tude of VA is kept small to simulate a noise source and not affect the circuit much There are four equations that we will use to analyze the performance of Figure 2 They are Op amp open loop gain VM al DBL TMi Op amp phase response VP 6 VP 5 Feedback loop gain weal VM 5 DB Feedback loop phase VP 3 VP 5 E Memory mapped variables E in line assembly language option Compile time switch to select 805 1 803 or 8052 8032 CPUs Compatible with any RAM or ROM memory mapping u Runs up to 50 times faster than the MCS BASIC 52 interpreter E
51. test points and an EEPROM programmer that includes zero insertion force sockets for DIP and SOIC versions of the EMU IC Beyond its use for application development the develop ment system lets you get comfortable with a somewhat intimidating chip Using a natural language interface you can realistically exercise all of the bq2001 s capabilities collect and analyze accumulated data and unravel the chip s inner mysteries Photo 1 The Computer Applications Journal shows what the development system looks like US AGAINST THEM So now that I ve given you a cursory overview of the battery management arsenal at our disposal we should be pleased because of the mighty armament we possess Surely we can gain the upper hand in the quest for battery supremacy But wait They can get it too The playing field is again level The only clear winners are the end users and the guys who came up with this magic L I would like to express my thanks to Benchmargq s Mike Calise for supply ing information and materials for this article John Dybowski is an engineer in volved in the design and manufacture of hardware and software for indus trial data collection and communica tions equipment SOURCE Benchmarq Microdectronics Inc 2611 West Grove Dr Ste 109 Carrollton TX 75006 214 407 0011 422 Very Useful 423 Moderately Useful 424 Not Useful ecent dialogue on the Circuit Cellar BBS has centered around th
52. the end result could be a similar temperature gain to maximum charging currents of up to 1 5 amps that of continuous charging but with a shorter charge time With lower cur rent pulses less temperature gain would occur with a similar charge time as with continuous charging 1N5821 D6 R10 AM BATTERY PACK R26 CRSNS INHIBIT Z ba R9 2k HLMP470 Figure 4 A complete charging system using a p chann at currents up to 3 amps 74 Issue 37 August 1993 el switching transistor can charge 4 12 NiCd or NIMH cells The Computer Applications Journal Modifying this approach to include a brief discharge period results in a method known as burp charging Here the 2 second interval could be arranged with a 1 05second charging pulse at 2 amps followed by a 0 005 second 2 amp discharge followed by an optional 0 9 second rest period The brief discharge actively depolarizes the electrolyte which tends to keep it in a low resistance state Charge efficiency may increase another five percent above that attained by using standard pulse charging By reducing the on time to a very short interval the effective current delivery can be choked back to a very low trickle level Although not really advantageous from a battery condition ing standpoint this method does provide an easy way to adjust the current flow without resorting to
53. those that prove unnecessary If you need to keep the case light at least have a thin mesh screen grounded inside the MICROCONTROLLERS e C Programmable Data Acquisition Control Test Excellent Support From 159 Qty 1 New Keyboard Display Modules Use our Little Giant and Tiny Giant miniature controllers to computerize your product plant or test department Features built in power supply digital 1 0 to 48t lines serial 1 0 RS232 RS485 A D converters to 20 bits solenoid drivers time of day clock battery backed memory watchdog field wiring connectors up to 8 X 40 LCD with graphics and more Our 195 interactive Dynamic makes serious software development easy You re only one phone call away from a total solution Z World Engineering 1724 Picasso Ave Davis CA 95616 916 757 3737 Fax 916 753 5141 Automatic Fax 916 753 0618 Call from your fax request catalog 18 144 The Computer Applications Journal Issue 37 August 1993 87 SOO TIME plastic Suppress every external input and isolate any output drivers by using open collector transistor arrange ments or a dedicated line driver The ULN 2803 works well on standard vehicles but may not prove suitable if you have any high power drive requirements Make the PCB as small as is feasible to minimize wire runs Make sure any pull ups downs are adequate especially on interrupt pins In such a hostile environment wou
54. through the program with a debugger include lt stdio h gt include lt sane h gt OSErr result ine SCSIBase define SCSIGlobals define dackWr define dackRd define sODR define sWrICR define sWrMR2 define sWrICR define sSER define sDMAtx define sTOMArx define sIDMArx define sCDR define sRdICR define sRdMR2 define sRdTCR define sCSR i define sBSR itdefine sIDR define sRESET de 0x0c00 Ox0COC 0x0201 0x0260 0x0001 0x0011 0x0021 0x0031 0x0041 0x0051 0x0061 0x0071 0x0000 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 main EventRecord event printf SCSI test printf This program requires Macsbug be GetNextEvent mDownMask keyDownMask amp event while result SCSIReset TestResult printf Click mouse to while asm Debugger MOVEA L LINK MOVEM L MOVEA L MOVEA L A7 A0 A6 OXFFF8 SCSIBase A3 SCSIGlobals A4 LEA sCDR A3 A0 Set AO to point to the Current address Data Register data lines 1 Once the Current SCSI off the SCSI the data on the lines can be implemented to detern for reading 2 Run the click Then breadboard sdata on the SCSI data lines sif desired compiled applica use the method The object is bus The issue 37 August 1993 cont nUse s to register Ot her user directly on the SCSI SCSIRD Test Code Out put Current Out
55. trimming component values Figure 6 shows how these variations look IT S AGAS Batteries provide juice to electrical circuits just like your gas tank pro vides juice to your car s engine thus a capacity determination methodology is defined and a new term is coined There is some merit to this analogue but there are some problems in taking this terminology too literally From the user s perspective this idea works well Easily grasped especially when depicted graphically it s handy to be able to determine the amount of fuel that is available to power your circuit It turns out that the problems associ ated with gas gauging are of a technical nature and stem from the fact that the size of the gas tank itself varies First of all the C rate designation defines the minimum capacity under nominal conditions In addition to this ambiguity the capacity will vary throughout the course of the battery s cycle life It s not unusual for NiCds to start out at 80 of their rated capac ity not acquiring 100 until being cycled several times finally falling back to 80 at the end of the life cycle With this degree of variation any attempt at capacity estimation can prove to be disappointing Accurately determining a battery s available charge at any given time can R1O BN monitoring circuitry really should be Res 39K included as part of the battery pack 1N4148 The idea behind gas gauging a
56. us today AX AX DX CT Place your order now and receive AL 0 SIGNAL MATH and DX A SIGNAL VIEW for i aE 195 O nl e gt 6 Or OC Real Time Devices Inc P O Box 906 State College PA 16804 814 234 8087 m Fax 814 234 5218 gt lt gt lt PF HOT Fr were MOM r 8 r OW x rrPrrwov0r Crs SHR AL 1 SHR AL 1 continued 123 40 Issue 37 August 1993 The Computer Applications Journal The circuit runs on 5 V The power supply is not critical and can be obtained from any source even the seldom used joystick port Simply steal 5 V from pins 1 8 9 and 15 and ground from pins 4 5 and 12 on the joystick port s 15 pin D type connec tor If power is obtained in this way the Parallel Expander should not be too far from the computer 3 feet or so The current requirement for the Parallel Expander is about 100 mA also wrote a test program PARXTEST PAS entirely in Turbo Pascal 6 0 available on the BBS The program uses the unit generated by PARXFAST UNI todoalltheparallel I O It is simple and straightforward there are no windows shadow boxes garish colors or anything like that but the program works and is intu itively easy to use My code includes the ability to exercise the Parallel Expander hard ware The tests include reading and writing random values read write timing bit set clear and interrupt action Before running the tests conne
57. watchdog timer The L 74 flip flop ensures that the watchdog times out after about 30 seconds following a hardware reset any access fo port 31C reduces the timeout to 1 6 seconds Much of the remaining circuitry drives indicator LEDsto reveal what s going on The Computer Applications Joumal Issue 37 August 1993 49 saving data to disk sending a message out the serial port or doing anything on a human scale just won t work Think fast and think final The MAX691 activates its Reset output when the supply voltage drops below 4 65 volts In a good PC the spec for the 5 V power at the card connectors is 4 875 V minimum so the Power Good signal should occur before the MAX691 triggers a reset The MAX691 also has a Reset output which you can use directly on 8031 systems Two additional power monitor outputs Battery On and Low Line are useful in some systems Check the data sheet for further hints and tips To recap the sequence of events during a power failure starts with PFO activating the CPU s NMI input The interrupt handler prepares for the coming shutdown and then enters a loop until either the MA X69 1 or the Power Good circuitry detects an invalid voltage and activates the system reset The MAX691 disables the RAM at the same time it activates the reset line When power comes back on Power Good and the MAX691 decide when the voltages are within tolerance and release the system reset line The BIOS then gets c
58. 16 interfaces up to 16 384 relays RD 8 REED RELAY CARD 6 relays 10 VA 49 95 RH G RELAY CARD 10 amp SPDT 277 VAC 69 95 EX 16 RELAY EXPANSION CARD 16 channel 59 95 ANALOG To DIGITAL 8 10 amp 12 BIT RESOLUTION ADG18 AD CONVERTER 16 channel 8 bit 99 95 Input temperature voltage amperage pressure energy 4sage energy demand fight levels joystick movement anc a wide variety of other types of analog signals Inputs may Se expanded to 32 analog or 128 status inputs using the 4D 16 ar ST 32 expansion cards 112 relays may be zontrolied using EX 16 expansion cards Analog inputs hay be configured for temperature input using the TE 6 emperature input Conversion RS 422 available P 4 port selector may be used to connect satellite ADC 16 nterfaces up to 4 096 analog inputs 16 384 status inputs and 14 336 relays Call for info on 10 amp 12 bitconverters terminal block and cable sold separately ST 32 STATUS EXPANSION CARD 79 95 Nput on off status of relays switches HVAC equipment hermostats security devices smoke detectors end other devices including keypads and binary coded outputs ravides 32 status inputs opto isolafors sold separately TE 8 TEMPERATURE INPUT CONVERSION 49 95 Includes 8 temperature sensors amp terminal black Temperature range is minus 40 to 145 degrees F PS 4 PORT SELECTOR 4 channels RS 422 79 95 Converts an RS 232 port into 4 sel
59. 256 X 1 X X 0 256 RE 00 S REM INITIALIZE DATA TRACK 110 S S H H H L REM ADD START CODE 120 FOR B 0 TO 1 REM BOTH BYTES 130 FOR 7 7 TO 0 STEP ET REM MSbit TO LSbit 140 IF X B AND 2 Z 2 Z THEN S S H ELSE S S L 150 NEXT Z REM DO ALL BITS 160 NEXT B REM DO BOTH BYTES 170 S S H L L L REM ADD END CODE 180 LPRINT S REM TOP TRACK 190 LPRINT CLK REM BOTTOM TRACK 200 LPRINT 210 GOTO 80 DATA MARK CHARACTER DATA SPACE CHARACTER CLOCK CHARACTER BUILD A CLOCK TRACK BREAK IT IN TWO MODELS ALSO AVAILABLE FOR 16 BIT EPROMS nex g Fore CALL OR FAX TODAY FOR MORE INFORMATION ON THE EEO8 AND OUR COMPLETE LINE OF EPROM EMULATORS Technical So utions PO BOX 462101 GARLAND TX 75046 2101 133 The Computer Applications Journal Issue 37 August 1993 59 8051SBC We are proud to offer our standard 8031SBC 10 Single Board Computer at a new low price just 79 perunit or as low as 49 each for quantity pur chases An 8031 with two JEDEC sockets one RS232 5V regulator expansion connector Optional second serial port 80031 or 32 At 149 our 552SBC 10 has the price and features you need right now It s an 8051 core processor with an eight chan nel 10 bit AID two PWM outputs cap ture compare registers one RS232 four JEDEC memory sockets and more digital VO And we didn t stop there You can add options
60. 4 60 4 80 5 45 5 70 6 75 6 75 6 75 6 90 7 50 8 00 8 10 8 40 9 75 9 90 10 40 11 85 12 00 12 00 12 70 14 25 18 90 20 00 33 00 64 00 UPS Ground 2nd day Next day 6 50 9 18 to 48 US states COD add 4 50 Canada 6 via USPS Air Small Packet no CODs Check MO or COD only no credit cards POs add 50 but call first CT residents add 6 sales tax Quantity discounts start at five parts Data Sheets Included inside an object and view the world from the object s viewpoint You can fly like a bird and see what it sees In the PCVR Renderer your viewpoint can be anything you want simply by specifying a three dimensional coordinate A VR program sets its viewpoint with the function create_viewpoint Thisfunction returns a pointer to a structure of type VIEWPOINT Figure 7shows this structure An example of a complete viewpoint setup is given in Figure 8 The new viewpoint is located at the origin in the world or 0 0 0 We have the ability to move the viewpoint to any location at any time Each time the viewpoint is changed the renderer recomputes the position of the objects in the world and redraws the screen One of the most powerful features of VR software is the ability to define several different viewpoints By defining several viewpoints the user can instantly change the direction they are looking just by pressing a key on the keyboard or by using some other input device For instance imagine be
61. 60 Jay St Santa Clara CA 95054 3309 408 980 1500 Fax 408 980 0400 Real time OS for embedded PCs and other systems Interlogic Industries 85 Marcus Dr Melville NY 11747 516 420 8111 Fax 516 420 8007 Passive backplane ISA amp EISA CPUs backplanes packaging JF Microsystems 3641 Frontier Rd Pasco WA 99301 800 532 2737 STD bus CPU and I O boards AIB PCt 240 00 iad Advanced Interface Board for IBM PC and Compatibles using the ISA bus Analog 8 software selectable analog inputs 12 bit ADC 8 microsecond cony time 6 software selectable input ranges Two 12 bit DAC s 5v to 5y Digital Two 8 bit ports for digital T O Timer Three 16 bit programmable timers Software Available Multi Purpose Lab Interface 49 95 A general purpose DOS based data collection analysis package Atlantis A general purpose Windows 195 00 or DOS 150 00 based data collection package with interupt capabilities A large number of sensors are available for use with AIB products Temperature Light Humidity Sound etc Issue 37 August 1993 DATA ACQUISITION AND CONTROL Logical Design Group Inc 6301 Chapel Hill Rd Raleigh NC 27607 919 851 1101 Fax 919 851 2844 PC compatible CPU boards with VME bus interface MCSI 2598G Fortune Way Vista CA 92083 800 347 MCSI ISA and EISA based SBCs Megatel Computer Corp 125 Wendell Ave Weston Ont
62. 7 0110 P O BOX 2042 CARBONDALE IL 62902 105 Cross Development Tools from 50 00 Cross Assemblers Extensive arithmetic and logical operations Powerful macro substitution capability Unlimited include file capability Selectable Intel hex or Motorola hex object file format Simulators Ten user definable screens Unlimited breakpoints and memory mapping Trace file to record simulator session Disassemblers Automatic substitution of defined label names for all jumps and branches Automatic insertion of supplied comments and expressions Broad range of processor specific tools Intel Motorola Zilog RCA Rockwell All products require an IBM PC or compatible MS DOS 2 1 or greater Same day shipment VISA MasterCard American Express and COD Unlimited technical support Thousands of satisified customers worldwide PseudoCorp 716 Thimble Shoals Blvd Newport News VA 23606 873 1947 FAX 804 873 2154 BBS 804 873 4838 804 106 The Computer Applications Journal Issue 37 August 1993 11 FEATURES 1 2 An Introduction to PC 38 12 issue 37 August 1993 based Virtual Reality 20 Oscillators Don t Amplifiers Do A Parallel Expander for the PC FEATURE ARTICLE Joseph D Gradecki An Introduction to PC based Virtual Reality 26 Real world Macintosh Virtual Reality is one of today s hottest development areas As usual the mass media movies especially have latc
63. 8990 y Link Computer Graphics Inc 369 Passaic Ave Suite 100 Fairfield NJ 07004 fax 808 8786 115 The Computer Applications Journal Issue 37 August1993 29 Sets the register to hex address 1 Initiator Command Register See Figure 4 Deassert ODR data on bus data lines Deassert ATN Deassert SEL Enable BSY BSY will remain on Deassert ACK Arbitration is NOT enabled Normal Mode Deassert RST NANANA oCoo0C0 cC0o Allows the register to be set 0 1 vu wA gt gt N O00000 v vuv pU OaRONM G OOG OGOGO W OF o Sets the register to hex address 2 AO A2 gt 010 2 See Figure 4 Mode Register 2 Disable Arbitration Disable DMA mode Disable BSY Monitor No interrupt for End of Process EOP No interrupt for parity error No SCSI parity checking Set to Initiator Mode Non Block DMA Allows the register to be set Sets the register to hex address 1 Initiator Command Register See Figure 4 hun oO oO Enable ODR data on bus data lines Deassert ATN Deassert SEL Enable BSY BSY will remain on Deassert ACK Arbitration is NOT enabled Normal Mode Deassert RST Huu tw wou nw it cCOoOCOCC0O0O Allows the register to be set Hoi ooo ooo0o0o00 Sets the register to hex address 0 The Output Data Register The data sent to the bus can be controlled by the CS line Allows the register to be set Set these data lines to the desired state to place the da
64. APPLICATIONS Bachiochi JOURNAL delicate balance between profit and loss for the company Most companies seem to drown in a sea of paperwork Some of this recordkeeping can be simplified and automated if the correct tools can be found Bar code wands have taken us a step closer toward automated data entry The wand is usually tethered by an umbilical cord which carries both power to and data from its light sensitive tip Data is presented as reflective nonreflective areas to the wand s infrared transmitter receiver converting the patterns into digital data signals Every time you use an ATM your card s magnetic data is converted into digital data by a magnetic read head Besides the obvious difference between media there is a secondary difference Bar code readers are brought to the data while card readers have the data brought to then will often use the ATM even during banking hours rather than stand in the queue As far as machines go it is one of the most user friendly around and after all if you do make it up to a teller they will call your account up on the computer anyway So avoid the middleman and speak directly to the source This month combine these two data collection methods to produce an inexpensive and easily implemented data input system In its simplest form it could be used as an identifica tion device or to keep a complete log Photo 1 1 h e Swipe Optical Reader is fairly e
65. CIRCUIT CELLAR a k MEASUREMENT amp CONTROL THE COMPUTER Introduction to APPLIC ATION S Virtual Reality Amplifier Design JOURNAL using Simulation Battery Charger Supervisor Chips August 1993 Issue 37 Beier eee cee 4r 4 3 95 US DIB RO INK Pavlov Would Be Proud nsome ways this month s theme is rather redundant While I m not suggesting that measure ment and control are synonymous and you can certainly have measurement systems that aren t even remotely connected to control do assert that you can do only very limited control without some sort of measurement or real world input to the system Even ona factory assembly line where dozens of operations are being performed over and over day in and day out without some kind of feedback to the system how would it know when something went wrong that needed fixing Yes there are some very stupid machines out there that require human supervision the entire time they are operating but what good is automation when the tedious human elementis still involved Along those lines you usually need a good amount of parallel I O for doing both measurement and control The IBM PC s output only printer port is pretty worthless for such a task and the Macintosh SCSI interface is daunting to many designers To correct both situations we have a pair of articles this month that deal with basic interfacing issues related to both the PC and the Mac
66. DX POP AX POP BP JMP CS gt Int020ff FIRMWARE SUPERVISION The MAX69 1 has one additional feature that believe is essential for any embedded system a watchdog timer As any INK reader should know a watchdog is simply a timer that resets the system after a predeter mined interval after a transition on its input pin The firmware must wiggle that bit often enough to prevent the timer from timing out The principle is simple correctly functioning firmware will reset the timer while locked up or stalled code will not A system reset clears the slate and starts all over again presum ably whatever the system is control The Computer Applications J our nal the power fail ov DX STAT_ADDR_A AX FPWR_GOOD_A so write protect OV DX CTLS_ADDR_A OV AX eNV WENABLE_A DX LED_ADDR_A Save bystanders aim at our segment again it is active nonzero says not our problem the RAM and lock up turn off write enable bit show that with right we are locking up decimal point ON jam up here until next reset restore bystanders indirect to old handler ling can stand a glitch in the outputs while the CPU recovers its wits If your system can t stand a brief interruption a watchdog isn t for you but you must provide some other way to detect failures and lockups because they will occur A particular problem with embed ding a stock PC is that the BIOS gets control when the CPU reset signal goes
67. EPROM VPP hi 32K EPROM Vpp hi 8K EEPROM Busy n c 32K EEPROM AI4 Gated CE Gated CE CE CE CE CE write it Just reducing the supply voltage is not enough because the RAM still draws enough juice to drain a battery in short order Nearly all CMOS RAM chips nowadays feature a low power standby mode which reduces their current consumption by several orders of magnitude A chip that pulls more than 50 mA during a normal read may need only 10 nA in standby mode Most of the chips enter standby mode when they are disabled which is controlled by the Chip Enable voltage on pin 20 But disabling the chip even with a low supply voltage is not enough The data sheets specify the minimum CE voltage to guarantee a maximum supply current Because the supply voltage will vary depending on the Pin 26 Pin 27 CE hi Gated WR Backup Vcc Al3 Gated WR Backup Vcc nic Pgm hi vcc Al3 A14 vcc n c Gated WR vec Al3 Gated WR vec Pin 28 The 8K EEPROM Busy output on pin 1 must not be driven by external ciruitry Figure P Although 8K and 32K byte RAMs EPROMs and EEPROMs all come in a 28 pin DIP package there are some crucial differences Five jumpers on the Firmware Development board cope with all the choices The Computer Applications ournal battery condition the voltage is actually specified as the difference between the voltages on pins 28 the power supply and pin 20 A 200 mV differential means t
68. Event Timer Counter Performance Histograms Hardcopy Output Disassembles 8 bit micros CEE On WHITEEOR CATALOG Supports VGA EGA HGA Demo diskette available 30 Day Money Back Guarantee DEALERS PLEASE WRITE OR FAX ON COMPANY LETTERHEAD INNOTEC DESIGN INC 6910 Oslo Circle Suite 207 Buena Park CA 90621 Tel 714 522 1469 FAX 714 527 1812 126 127 42 Issue 37 August 1993 The Computer Applications Journal Listing 1 continued NW END PROCEDURE QUTWORD OW WORD BEGI AS OV BX OW OV AL BL OV DX OUTPORT T DX AL DX CTLPORT AL 0 DX AL Word in BX Low byte in AL Sendl ow byte to data Set up decoder Do it Release decoder Send high byte in same TPORT DX CTLPORT AL 03 DX AL AL 07 DX AL AL 03 DX AL HAL 4 EEG Biofeedback Brainwave Analyzer The HAL 4 kit is a complete battery oper ated 4 channel electroencephalograph EEG which measures a mere 6 x7 HAL is sensitive enough to even distinguish different conscious states between concentrated mental activity and pleas ant daydreaming HAL gathers all relevent alpha beta and theta brainwave signals within the range of 4 20 Hz and ioc itina serial digitized format that can be easily recorded or analyzed HAL s operation is strdighifforward Tt samples four channels of analog brainwave data 64 times per second and transmits this digitized data serially to a PC at 4800
69. Fax 408 734 2140 Rackmount and factory floor enclosures Symmetric Research 15 Central Way 9 Kirkland WA 98033 206 828 6560 Fax 206 827 3721 DSP32C based PC bus coprocessor Systek 415 N Quay St Ste 6 Kennewick WA 99336 509 7351200 V25 and V50 based SBCs Systronix Inc 555 South 300 East Salt Lake City UT 84111 801 534 1017 Fax 801 534 1019 SBC with 8088 type CPU temp sensor and 2 x 24 LCD Teknor Microsystems P O Box 455 Sainte Therese Quebec Canada J7E 4J8 514 437 5682 Fax 514 437 8053 Passive backplane CPU and board packaging EXPRESS CIRCUITS Texas Micro P O Box 42963 Houston TX 77242 9910 800 627 8700 Fax 713 541 8226 Passive backplane packaging and boards Versalogic Corp 3888 Stewart Rd Eugene OR 97402 800 824 3163 STD 32 CPU and I O boards WinSystems Inc 715 Stadium Dr 112 Arlingon TX 760 11 8 17 274 7553 PC 104 CPU and I O boards Ziatech Corp 3433 Roberto Ct San Luis Obispo CA 93401 805 541 0488 Fax 805 541 5088 STD 32 bus and ISA CPU and I O boards MANUFACTURERS OF PROTOTYPE PRINTED CIRCUITS FROM YOUR CAD DESIGNS TURN AROUND TIMES AVAILABLE FROM 24 HRS 2 WEEKS Special Support For TANGO PCB TANGO SERIES II TANGO PLUS PROTEL AUTOTRAX PROTEL EASYTRAX smARTWORK HiWIRE Plus HiWIRE II EE DESIGNER EE DESIGNER III ALL GERBER FORMATS e FULL TIME MODEM e GERBER PHOTO PLOTTING WE CAN NO
70. Formula Atlantic cars with the Ford Cosworth motors These turned out to have some of the most severe vibration problems around cars both larger and smaller had less intense vibration This manifested itself in the failure of the clock crystals over time Once again the failure would only occur on track at maximum stress sometimes the box would get lost but usually would find its reset point and look like a reset while operating In the pit the hairline fracture of the crystal did not prevent it from operating There are two basic types of construction for HC49U style crystals One type the bad kind for us uses solid flat ended leads with a slot which the crystal wafer slips into The other type the good kind uses tiny looped springs to hold the crystal ended up buying crystals made to order which is not terribly more expen sive than off the shelf even in modest quantities The use of smaller crystals which are more readily available these days is clearly a benefit We invite you call the Circuit Cellar BBS and exchange messages and files with other Circuit Cellar readers It is available 24 hours a day and may be reached at 203 871 1988 Set your modem for 8 data bits 1 stop bit no parity and 300 1200 2400 9600 or 14 4k bps ARTICLE SOFTWARE Software for the articles in this and past issues of The Computer Applications Journal may be downloaded from the Circuit Cellar BBS free of charge For those unable to d
71. General purpose O port AL 809 Control and monitoring of DX AL single board computers J BX Save 16 bit word Connecting your PC to digital continued instruments PC Based Logic Analyzers NIERPRISES ORDERS 800 477 4181 orvers 410 437 2324 INFO 410 437 4181 VISA MASTERCARD AMEX 1292 MONTCLAIR DRIVE FAX 410 437 3757 FEDERAL EXPRESS NEXT DAY AVAILABLE PASADENA MD 21122 x 10 HOME AUTOMATION MODULES amp CONTROLLERS LEVITON HOME AUTOMATION MODULES amp CONTROLLERS STANLEY X 10 COMPATIBLE GARAGE DOOR OPENER ENERLOGIC X 10 TWO WAY COMPUTER INTERFACE 359 99 RCS X 10 COMPATIBLE 4 CHANNEL DPTP RELAY 160 REDAC ADD oarat inputs ANALOG INPUTS amp RELAY OUTPUTS TO X 10 ECS SOFTWARE WIT aut N Home automation 250 SKYLINE CONTROL sortware UPGRADE FOR x 10 CP290P EASIER TO EDIT USE DUSK AND DAWN CONTROL 49 95 OR 20 W CP290P APPROACHING HOME AUTOMATION ook onx 10 1890 UNIVERSAL ELECTRONICS one For aLL REMOTESFROM 41 24 SSI potey pro LOGIC SURROUND SOUND DECODERS AMPS amp SPEAKERS AR POWERED PARTNERS cowputer serf POWERED SPEAKERS PANASONIC HYBRID PHONE SYSTEM Sophistication at Low Cost PANASONIC PHONES FAX amp ANSWERING MACHINES 1D160 50MHz 595 MAGNAVOX CLOSED CIRCUIT TV SYSTEM ID161 100 MHz 695 RAINDRIP LAWN GENIE High Speed 8K Trace Buffer 16 timing channels PC TELE VISION watcx tvon COMPUTER WITHWINDOWS 449 WSPEAKERS expandable to 32 state channels M ulti Level Triggering State Pass Counting
72. INE ALI ke doles NEWS Edited by Harv Weiner 6 TONE DECODER WITH SERIAL PORT International MicroPower has introduced a Commer cial Telephone Line Decoder that combines many features at a low price The Digit Snatcher II simplifies the capture and storage of digital tones by means of an LCD display with built in help menus An Intel micro processor controls the storage of thousands of digits offers automatic help messages and sends and receives serial RS 232 data The Digit Snatcher II also incorporates Caller 1D capture A built in microphone with dectronic auto matic level control and noise filter allows acoustic capturing of DTMF dialing as well as Caller ID eliminat ing the need for an electrical connection between the source and Digit Snatcher II The unit will decode and store DTMF signals from acoustic signals coming from TV or radio as they are heard SOLID STATE TEMPERATURE MEASURING DEVICE The unit features a storage capacity of up to 4000 digits A built in day date and time stamp option is available marking each series of digits with the current date and time Stored information will be retained for up to 5 years even while the unit is turned off which means the Digit Snatcher II can be taken into the field to decode and store digits and later be connected to a desktop or laptop computer for data retrieval A 5 mm coaxial DC power jack is standard but the unit will work for up to 26 hours on an intern
73. If the polygon is directly in Object A Object B Object A Figure 4 For proper 3D effect objects are sorted with respect fo their z coordinate a When object A is in front of object B object B is drawn first b Similarly when object B is in front object A is drawn first The Computer Applications Journal front of the light then the full inten sity of the light source is reflected from the polygon and it is colored accordingly If the polygon is at an angle to the light source then only the fraction of the light rays whose angle of reflection generates a ray which pierces the plane of the view space will be used to color the surface By using a shading scheme each of the polygon surfaces can have different shades of the same color based upon the inten sity of the reflected light rays DRAW The last step in the rendering process is drawing the objects to screen memory Significant time and energy is given to this subject by developers of rendering packages because of the amount of time spent drawing to the computer scr
74. Includes Binary Technology s SXA51_ cross assembler amp hex file manip util E Extensive documentation Tutorial included m Runs on IBM PC XT or compatibile Compatible with all 8051 variants BXC51 295 508 369 9556 FAX 508 369 9549 E Binarv Technology Inc P O Box 541 Carlisle MA01741 a Issue 37 August 1993 23 To see how good the op amp model is I used the first equation to produce AC STABILITY ANALYSIS Figure 3 which shows the classic Date Time run 01 01 80 00 29 10 Temperature 27 0 single pole frequency response 50 eevee J pex q ferree fesseeees Jerse Comparing the curve of Figure 3 to the same curve on the LMC660 data sheet shows a very close approximation of the frequency response plot of an LMC660 op amp To determine circuit stability I made Figure 4 using the last two equations This circuit is potentially 0 L Se E i unstable At 63 kHz the phase 1 0 10h 100h 10Kh 100Kh 1 0Mh 10Mh response climbs to 173 This is a o DB VM 3 VM 5 phase margin of only 7 and violates S rE AA aes pee ET TEREE S ILITI CELETTE Coote the rules of thumb stated above A lot of the excess phase shift comes from C3 which models the capacitance found in many twisted wire pair cables Some method of neutralizing C3 must be found I made Figure 5 with C2 set to 1500 pF The phase peak shifted to 2 8 wees fore enone peseeeeee Je KE kHz a
75. Kbit to 8 Mbit 85 40ns EPROMs Accepts Binary Ext Intel amp Motorola formats Fast download from printer port 1 Mbit Sec Double sided SMT design 2 2 x1 9 PCB Jumperless configuration through software Ni Cd battery backup Power up emulation Cascadable to 128 bits Generates RESET Comes complete with software and cables Optional 8 16 bit DIP PLCC adapters 15 DAY MONEY BACK GUARANTEE Buya 1M Jet before 9 93 get the 2nd MBit FREE PROMJet 64K 1M 2M 85ns 1751295 PROMJet 64K 4M 8M 85ns 4951695 WESTEC Research Corp 213 664 8909 2750 Riverside Dr 205 LA CA 90039 USA 120 k k 3 o 0700 ed e assemDp our progra a oe BA ame da pping and 30 da ompetent te a ppo A potle erties O D 121 The Computer Applications Journal Issue 37 August 1993 35 A Parallel Expander for the PC Have you ever wondered why IBM didn t do it the right way and make the parallel printer port bidirectional With a few chips and some special software you can make the PC s printer port into something useful Issue 37 August 1993 FEATURE ARTICLE John F Lenihan ithout special hardware all PCs have only two ways to connect to the outside world serial and parallel ports The advantages and drawbacks of the serial port are well known so won t discuss them here However the parallel port unlike the serial port tends to be used in a predictabl
76. MBEDDED CONTROLLER The Syndetix Embedded Controller S E C is designed for systems that require powerful controller functions With its zero wait state Flash memory and low power consump tion it is ideal for in circuit programmable embedded controller applications Updates for both CEBugger and the DLL software are available from an on line BBS for registered users CEBugger incorporates multilevel error checking and identifies four different classes of errors media errors such as loss of carrier bad checksum and noise bursts notifications nonstandard NPDU or DLL control field warnings borderline timing errors and protocol violations Error checking for each of these classes may be independently enabled or disabled The CEBugger Protocol Analyzer for power line sells for 3095 Analyzers for twisted pair infrared and coax are available for 2995 each Command Control Inc 8800 Roswell Rd Ste 130 Atlanta GA 30350 1875 404 992 8430 Fax 404 993 3603 504 externally battery backed and the RS 232 port may be turned on and off as required with external circuitry to conserve powe The S E C sells for 750 in single quantity The price includes a comprehensive user s manual as well as Motorola manuals on the CPU and CPU32Bug The small 4 11 x 2 61 x 0 4 board features an MC68332 or MC68331 CPU 256K or 1 MB of SRAM 256K or 512K Flash memory 128K EPROM and a built in
77. OS for Embedded BIOS product embedded systems our Embedded DOS operating system supports the entire MS DOS API with full reentrancy Its built in turns nonstandard hardware into PC compatible computing engines even 186 and V series systems high performance microkernel supports y threads timers semaphores configuration options full message ports and queues fers 32 000 levels of priority in both preemptive Embedded BIOS offers the and nonpreemptive modes Full source 106 000 lines control and lowest price of and reasonable royalties Now with over 95 source code 30 000 and o lines and no royalties most flexibility best any BIOS in the world Our high performance software analyzer captures time stamps and records hardware interrupts DOS calls BIOS interrupts and user defined events in real time for later analysis of race conditions interrupt activity and service times absolute must have for developers involved in asynchronous software debugging Runs under any DOS environment with most real time kernels Since 1989 we ve been ddivering the core software of the best 80x86 embedded designs We ve launched rockets controlled satellites flown in military and commercial avionics scheduled traffic lights rented out cars handled bank transations switched teleohone calls delivered faxes and even worked for Uncle Sam for starters More and more developers are turning to General Software
78. TLPORT Set up decoder for nibble 0 i MOV AL 0A A cost effective solution Mov A SOE ADA221 0 features a ated Enable decoder to read nibble Q E bie eer IN AL DX Readin nibble 0 E bit analog inputs im 5 10 0 10V selectable input range bs i ee ae IE programmable auto channelscan i INEN l A W programmable burst mode SHR AL 1 SHR AL 1 SHR AL 1 Shift everything lower M software amp external triggers pacer clock TEST AL 10 Tf B4 set clear it and set B3 MM on demand DMA transfer JZ l Im programmable gain 1 2 4 8 1 10 100 1000 SUB AL Mm 3 cascadable 16 bit counters OR BX A Save nibble in BX at ee digital VO i nas ROR BX C Set up BX for next nibble two it analog outputs selectable range 7 E rtdLinx Universal TSR DOS driver OV DX Disable decoder E Labtech Notebook driver OV AL U DX A HARDWARE SOLUTIONS DX C Do nibble 1 Our AIC family also includes AT analog I O AL boards 5V only A D amp control boards for D Ti A portable PCs 4 20 mA current loopoutputs A and opto 22 compatibility a DX A SOFTWARE SOLUTIONS DX a Select the power and performance of aa SIGNAL VIEW or SIGNAL MATH fror L B8 our library of application programs for moni AL 80 itoring data acquisition and analysis control AL 1 SHR AL 1 SHR AL IDSP and 3D graphics AL 10 2 AL 08 For more information on these and other BX AX ISA bus and PC 104 products BX CL call write or fax
79. W WORK FROM YOUR EXISTING ARTWORK BY SCANNING CALL FOR DETAILS Express O Circuits 1150 Foster Street e PO Box 58 Industrial Park Road Wilkesboro NC 28697 139 The Computer Applications Journal Quotes 1 800 426 5396 Phone 919 667 2100 Fax 919 667 0487 Issue 37 August 1993 69 Support For Your Batteries 70 Issue 37 August 1993 EMBEDDED TECHNIQUES John Dybowski hen thinking about this month s article I considered a cursory survey of all the available battery support peripherals on the market thought could highlight and compare some of their more prominent features Instead decided to narrow my focus and cover just a few parts so could provide more in depth details really like what Benchmarg is doing so l Il concentrate on their offerings Having started with the bq2003 fast charge IC last month IH continue now and elaborate more fully on its capabilities and show you how to use it in several different charging configurations BQ2003 RECAP The bq2003 is a complete fast battery charger circuit suitable for NiCd NiMH or lead acid batteries It can operate in a stand alone fashion or can be embedded into a battery operated system as an integrated function block Charging current can be generated by use of a built in high efficiency switched mode current regulator or an external linear current source can be gated through the device to prov
80. a Pena ties qe Tabh E OET h 100Kh 1 0Mh 10Mh FREQUENCY Figure 3 The classic single pole frequency response of the LMC660 op amp as determined by PSpice matches the part s data sheet very closdy forms a voltage divider with the load The value of Royr is determined by solving the following formula MOVE OVER INTEL MICROMINT SOURCES 80C72 CMOS BASIC CHIP Micromint has a more efficient software compatible successor to the power hungry Intel 8052AH BASIC chip The 80C52 BASIC chip was designed for indus trial use and operates beyond the limits of standard commercial grade chips Micromint s BOC52 BASIC chip is guaranteed to operate flawlessly at DC to 12 MHz over the entire industrial temperature range 40 C to 85 C Available in 40 pin DIP or PLCC 25 00 14 50 15 00 80052 BASIC chip OEM 100 Qty Price BASIC 52 Prog manual MICROMINT INC 4 PARK ST VERNON CT 06066 Q amp Q TO ORDER CALL WS 1 800 635 3555 119 AC STABILITY ANALYSIS Date Time run 01 01 8000 08 49 50 T ae eee 4 an wennene 1 weneurene t weemeene 1 unanne 0 cneennsl 7 nssnnn q ETETETT t anasunsos piep nsanas 4 Oh 10h 1 00h 1 D DB VM 3 VM 5 OKh 100Kh 1 0Mh 10Mh I 1 0 10h 100h 1 0Kh 10Kh 100Kh 1 0Mh 10Mh o VP 3 VP 5 FREQUENCY Figure 4 At 63 kHz the phase response climbs to 173 leaving a phase margin of only 7 and indicates a potentially unstable ci
81. a linear approach Using external switching transis tors the bq2003 can be set up to operate with either a p channel or an n channel output power stage For charging currents bdow 3 amps a p channe output stage is usually used since fewer support components are required If the charge current is above 3 amps using an n channel FET usually turns out to be more economi cal even though additional parts are needed to establish the proper gate drive for the n channel FET Figure 4 shows a complete charging system based on a p channel switching element This configuration can handle from 4 to 12 NiCd or NiMH cells at currents up to 3 amps Here MOD drives a small signal DMOS FET Q3 that turns on when MOD is high This FET in turn drives the p channel power FET Q1 into en hancement Current through the in ductor ramps up and the resulting volt age developed across the sense resistor R26 is delivered to SNS via an R C network composed of R4 and C8 When SNS reaches 0 250 volts MOD goes low and the p channel FET Q1 turns off At this time a flux reversal occurs in the inductor causing the catch diode D10 to conduct Charge current is delivered to the battery until the inductor current ramps down and the voltage at SNS reaches 0 220 volts The cycle now repeats with MOD go ing high From this description you can see how the linear configuration described above switches charging cur rent continuously by simply pul
82. advantage of small size and with the appropriate spacers good rigidity Since it is electrically quite similar to the ISA bus the many members of the consortium are hard at work porting existing ISA bus designs and chipsets to PC 104 As an alternative to a standard like VME STD 32 or PC 104 you can go with a particular company s proprietary bus should it offer functional advantages such as espe cially small size or unique packaging For example the E S P Extremely Small Package line from DOVatron formerly Dover Electronics Manufac turing combines small form factor at 17 x 5 2 even smaller than PC 104 with downsized plug in backplane packaging Photo 4a Meanwhile Micro Link takes another tack by mapping the ISA bus signals onto the 3U single height Eurocard format with its robust DIN connector and four sided mounting stability Photo 4b This combines the best of both worlds by exploiting Photo 4a The Extremely S mall Package E S P line from DOVatron combines small form factor with conventional plug in backplane packaging Photo 4b Microlink maps the ISA bus signals onto the 3U Eurocard format shock and vibration specifications Photo 4 e The Radisys EMC family packages the PC in a true industrial strength unit with extended temperature t The Computer Applications Journal heavy duty and standardized Eurocard packaging while allowing the use of low co
83. al 9 V battery A one button locking device allows the entire unit to be opened for battery access in less than 5 seconds The compact hand held unit comes in a hard anodized extruded aluminum case which makes it resistant to scratches and marks It can be easily cleaned with a damp cloth The clock calendar option is easy to use and contin ues to keep track of the date and time while the unit is off Setting the date and time is accomplished in the same manner as a simple digital clock and automatic correction for short months and leap years is included The Digit Snatcher features help menus for ease of operation The unit will prompt with choices if an appropriate selection is not entered The Digit Snatcher II sells for 179 with 1000 digits of storage A 2000 digit storage unit with Caller ID and serial port sells for 289 All options sell for 550 A 20 page operator s manual is available on request International MicroPower Corp 65 Palm Dr Camarillo CA 93010 805 482 2870 Fax 805 389 1274 A solid state user modifiable temperature sensing device that requires no batteries has been introduced by Parham P Baker and Associates Inc The Temp A Chip interfaces to any RS 232 serial port and enables temperature monitoring from the computer Unlike other temperature sensors the Temp A Chip provides a more linear measurement of temperature because of its solid state design No batteries are required and the Tem
84. an be done to lessen the need for the handi capped user to purchase special and typically expensive equipment the more successful the concept will be The final pair of patents relate to the hearing impaired The first of these presented in Abstract 7 provides a visual indication of the direction and strength of sounds emanated The Computer Applications Journal Issue 37 August 1993 79 LUPO TALK Patent Number Issue Date Inventor s Assignee US References Title Abstract Patent Number Issue Date Inventor s Assignee US References Title Abstract Patent Number Issue Date Inventor s State Country US References Title Abstract near the user When embedded within a pair of eyeglasses for example the user would be directed toward the source of sounds The benefits could range from the convenience of knowing that someone out of the line of sight is speak ing to the safety of knowing about an oncoming vehicle 82 Issue 87 August 1993 5 1 07 467 1992 04 21 Jorgensen Adam A Jorgensen Otto A Jorson Enterprises Inc 2 500 638 2 580 560 3 366 922 4 292 678 4 712 003 4 761 770 4 907 136 Echo location system for vision impaired persons Echo locating apparatus for a vision impaired person which includes a sound emitter for emitting a stream of sound bursts of ultra high frequency at least one receive channel having a microphone for receiving echoes of the sound bursts and generating echo
85. any power source that provides enough voltage for the RAM will work 46 Issue 37 August 1993 An NEC Static RAM Application Note reviewed for this project mentioned several UL requirements for lithium cell backup circuits Even if your product doesn t need UL approval the guidelines make sense Bear in mind that haven t read the UL regulations themselves so don t depend on my suggestions to get your design approved Lithium cells react explosively to recharging so you must prevent excess current from flowing into the cell Typically you would use a Schottky barrier diode in series with the battery because the forward drop of an ordi nary silicon junction diode is far too high The UL requirement limits the The Computer Applications Journal charging current to 1 of the cadl s capacity prorated by the possible charging time over the battery s service life This can be a surprisingly small number so check your diode specs carefully For example if the power supply will be on 8 hours per day and the cell capacity is 250 mAH the reverse charging current may not exceed 85 nA which is derived from the follow ing formula 0 01 x 250 mAH 8 hours day x 365 days year x 10 years or about 85 nA The worst case is for continuously powered systems because the cell will always see recharging current You may need a bigger battery than the RAM s standby current would lead you to expect if only to boos
86. asy to build and serves well as a portable unit The Computer Applications ournal Figure 1 7wo pieces of scrap plastic rails are placed in line with the enclosure tabs A card is swiped through these fabs in between the two rails A photosensor positioned af the left rail slot reads data as it passes by for task management or security purposes The heart better yet eyes of this month s project uses a pair of reflec tive photomicrosensors stacked inside a small 3 x 4 enclosure The enclo sure is modified with a card slot and voila an optical swipe reader is born Two sensors are used to provide two tracks of information This configura tion opens many possibilities for experimentation ENCLOSURE PREPARATION Since the enclosure have chosen has mounting tabs on the bottom slotted the top surface parallel to the longest dimension adjusted my table saw blade for a depth of set the rail at 1 and ran the enclosure through top side down Always use a feed stick to move your work through the business end of the table saw you ll probably need those fingers later The slot supports are made from scrap pieces of plastic although you might want to use extruded aluminum angle A single right angle piece forms one side and the bottom of the slot This is glued in place at the appropri ate level even with the bottom of the slot A second piece sits on the first A small spring keeps t
87. ate The PCM AIO also contains an Analog Devices AD7537 dual 12 bit digital to analog converter DAC Two idependent DACs are in one monolithic chip that is configured to provide two 0 to 5 volt outputs The input ction is double buffered to allow simultaneous update of both DACs These registers latch the 12 bit digital word ad keep the D A converter s output constant until it is updated with a new value in one step The PCM AI0O operates over the temperature range of 25 to 85 C The module contains low power CMOS gic devices to reduce current draw and increase product reliability It requires only 200 milliwatts of power The nit measures only 3 6 by 3 8 It is an 8 bit stackthrough module that can be used in a stand alone stack or as a 1ezzanine bus stacked atop a larger single board computer The PCM AIO sells for 295 and carries a two year warranty The PCM AIO 80 a lower cost version offering channels of A D input only sells for 250 WinSystems Inc 15 Stadium Dr Arlington TX 76011 817 274 7553 Fax 817 548 1358 COMPACT EPROM EMULATOR An ultracompact from 64K 8K x 8 to 8M battery backed high speed allow 16 32 64 and PROM emulator from 1M x 8 The PROMffet is RAM a download rate of 1 128 bit emulations Vestec Research contained on a 2 2 x 1 9 Mb s and easy to use Options include a 40 pin mulates all EPROMs PC board and features software DIP adapter 32 and 44 The PROMJet pin PLCC adapters and c
88. ational constant r radius distance and c the speed of light The book even says Experiments comparing Earth based and airborne clocks have shown that the gravitational time dilation described by the equation occurs In a series of 15 hour flights at 30 000 ft the time dilation was 47 1 x 10 seconds find that very fascinating so am indeed able to notice a difference in time due to gravity with my cesium beam wonder what the difference is due to me at sea level and NIST Probably small l Il figure it out later thought I d write this first Msg 11985 From BOB PADDOCK To TERRY NORRIS I can t let a good discussion on time travel by me without comment especially if can get in some relativity bashing along the way Let s start with the conventional This part taken from A Matter of Time by Richard S Moseson N2BFG CQ magazine December 1985 pages 35 38 How do atomic clocks work And who invented them As Roger Beehler of the National Bureau of Standards explains the clock s operation cesium atoms are put into a tube called a resonant cavity inside a long beam machine which is the atomic clock The atoms are irradiated with an electromagnetic field and they align themselves in the field with one magnet They flip back and forth at a fixed rate and keep doing so as long as the field is at the exact reso nant frequency If the field is off frequency the atoms do nothing That ra
89. benefit relative to ISA with its 8 16 bit connector and full half slot dilemmas is that all STD STD 32 boards are the same size and thus can be fully supported on all sides Boards flapping in the breeze are particularly a no no if vibration is an environmental concern Photo 3a is an example of a STD 32 embedded PC in this case the Ziatech 8902 with plug on super VGA adapter The latest standard contender is the PC 104 spec which is being proposed as an extension to the IEEE P996 draft ISA specification Unlike all the other buses PC 104 is a mezza nine type stackable bus featuring like ISA either one P1 8 bit or The Computer Applications ournal Photo 3a The Ziatech 8902 STD 32 embedded PC includes support for a plug on super VGA adapfer two P1 amp P2 16 bit connectors Photo 3b shows a typical PC 104 stack from Ampro consisting of a 286 CPU board an Ethernet interface and VGA controller Configuring a system does take a little thought to meet the constraints of the mezzanine scheme For ex ample 8 bit boards need to be on top since they don t pass the 16 bit signals on and a stack can only handle a single high profile board for ex ample a relay board on top Also the appropriate mix of stackthrough and nonstackthrough connectors is called for Debugging and maintenance is complicated by lack of access to the innermost cards The PC 104 approach has the
90. bps There using a Fast Fourier Transform to determine frequency amplitude and phase components the results are graphically displayed in real time for each side of the brain HAL 4 kit 179 00 plus shipping e The Circuit Cellar Hemispheric Activation Level detector is presented as an engineering example of the designtechniques used inacquiringbrainwave signals This Hemispheric Activation Level detector is not a medically approved device no medicalclaims are made for thisdevice and it should not be used for medicaldiagnostic purposes Furthermore safe use requires that HAL be battery operated only lines to latch low byte way Using optoisolators to monitor and control high voltage systems the Parallel Expander UL John Lenihan has been a Radio that he worked as an Electronic Technician and Field Engineer Software for this article is avail able from the Circuit Cellar BBS issue Please see the end of ConnecTime in this issue for downloading and ordering infor mation 410 Very Useful 411 Moderately Useful 412 Not Useful Sonar Ranging Experimenter s Kit Targeting Ranging Machine Vision The Circuit Cellar TI01 Ultrasonic Sonar Ranger is based on the sonar ranging circuitry from the Polaroid SX 70 camera system The TIO1 and the original SX 70 have similar performance but the TI01 Sonar Ranger requires far less support circuitry and interface hardware The T101 ranging kit consists of a Polaroi
91. ce the illusion of three dimen sional objects A head mounted display has two Liquid Crystal Displays LCD one in front of each eye which display slightly separate images The brain fuses the images into a three dimensional world Additionally the user might use some kind of three dimensional input device like a glove wired with sensors to interact with the virtual world This interaction is what separates a three dimensional game and a VR applica tion This does not come cheap Current pricing for top of the line VR systems can range from 80 000 to 500 000 depending on the system s capabilities and the user needs CONVERTING YOUR IBM PC TO A VR MACHINE An alternative to the high priced systems is a homebrew setup Using several simple interface circuits a developer can add the Mattel Power glove and Shutter Glasses from Sega or Toshiba to the parallel and or serial ports of an IBM compatible PC These two pieces of hardware enable the user to interact in a three dimensional virtual world right in their home As the user s interests advance peripher als such as 3 D sound head position tracking and head mounted display systems can be built and added to the system to give a more realistic sense of immersion in their virtual world However all the hardware is useless without software to control it VIRTUAL REALITY SOFTWARE Software for a VR system is called arendering package This software takes numeric
92. circuit is similar tothe previous setup for the SCSI bus lines however a single pull up resistor has been substituted for the bus termination dual resistor setup The DIP switch is used to maintain the control data lines at ground potential The Computer Applications Joumal Issue 37 August 1993 27 Figure 3 The target breadboard is the Mac s fink fo real world signals In the final implementation the target will Target Breadboard SCSI Bus Initiator need some intelligence a processor or PAL tocontro the 5380 and automatically direct raw dataonto the SCSI bus Figure 4 The 5380 SCSI interface chip has eight registers that are used to communicate withthe host processor Output Data Register ODR Bit 7 DB7 DB6 DB5 8 Bits Hex Addr 0 Write Only Initiator Command Register ICR Bit 7 LA DIFF RST TEST 8 Bits Hex Addr 1 Mode Register 2 MR2 Bit 7 BLK TARG PCHK 8 Bits Hex Addr 2 Read Write Current SCSI Data CSD Bit 7 Bit 0 DB7 DB6 DB5 DBO 8 Bits Hex Addr 0 Read Only Target Command Register TCR Bit 7 Bit 0 X X X VO 8 Bits Hex Addr 3 Read Write Select Enable Register SER Bit 7 D7 D6 DBS DB4 DB3 DB2 DBI Bit 0 DBO 8 Bits Hex Addr 4 Write Only urrent SCSI Bus Status CSB Bit 7 RST BSY REQ MSG cD 10 SEL Bit 0 DBP 8 Bits Hex Addr
93. ct a 25 wire cable from the outputs to the inputs from PO3 to PO2 The test program gives any necessary instructions for example using a logic probe or a scope to test strobes and when to ground the interrupt pin The interrupt tests might not work on an XT class computer if any printer port higher than LPT 1 is used since the LPT2 interrupt might be used for a hard disk Use caution when testing interrupts on an XT or with an early version of DOS used a 6 foot 1 8m 25 wire shielded cable to connect the com puter to the Parallel Expander during tests with a 3 foot 0 9m 25 wire shielded cable serving as an input to output loopback cable There were no failures or problems during many hours of testing with this setup can t overemphasize the importance of using good quality shielded cable make sure cable shields are connected to the connector shells TRADEOFFS AND APPLICATIONS So why should you use something like the Parallel Expander when lots of Free Demo Disk Call 1 800 221 6630 What is C thru ROM ROM Your Borland or Microsoft C C Code C_thru_ROM is the complete ROM development software tool kii It lets you run Microsoft and Borland C and C programs on an embedded 80x86 CPU without using DOS or a BIOS C_thru_ROM saves you money There are no DOS or BIOS royalties to pay for your embedded systems C_thru_ROM is complete It includes the following and much more Supports Borland
94. cularly accurate You may need to experiment to find the right value for your application Remember that a slow watchdog is better than a fast one in most cases Figure 5 shows the new O bits on port 3 1 C which is identical to port 31E that we used for the LED digits and DIP switches Although only three bits are defined thus far I ve got plans for the remainder never fear The Firmware Development Board now sports several indicator LEDs so you can tell at a glance when RAM writes are enabled Reset is active the watchdog is toggling and how long a watchdog timeout will take The LED drivers are part of the LS245 used for the interrupts from the 8254 timer so the outputs are always enabled GETTING DOWN TO CODE The RAM is similar enough to the E EPROM we covered last month that just converted M EMT E ST test program into RAMT E ST by ripping out the EEPROM write timing and expanding the memory tests to include all 32K bytes There s nothing new here so won t show the listings but do download the code to check out your wiring Although a watchdog timer is essential for a production system it can be a serious nuisance while you re developing and testing code like RAMTEST 1 disabled my board s watchdog by yanking the system board Reset connection The red LED then indicates when the MAX691 s Reset output is active which helps track down problems if it ever goes on you ve goofed But you do need som
95. currently that make my question valid 1 That technology allows my new cesium beam to be more or equally stable as the early experiment 2 That the differ ence might be substantial over time know we don t intend to dispose of the cesium beam soon 3 That understand that short term differences might be too darn small to care about like when calibrating a good counter Msg 11611 From DAVID PARRISH To TERRY NORRIS wouldn t worry too much According to Einstein time dilation is given by 84 Issue 37 August 1993 The Computer Applications Journal onducted by Ken Davidson T T sqrt 1 V c with c 2 3 x 10 km s velocity of light In other words if the velocity difference is 10 000 MPH the difference in the times is in the twelfth decimal place Msg 11630 From DAVE TWEED To TERRY NORRIS Sure it s valid to have a clock accurate enough to measure relativistic effects That s part of the fun of owning one or two One experiment that has been performed was to put a clock on each of two jets one of which circumnavigated the globe over the equator flying east the other did the same thing flying west Relativity predicts that one of the planes will see slightly less centripetal acceleration earth s rotation air speed vs earth s rotation air speed and therefore a slightly faster passage of time Sure enough the two clocks disagreed by the amount predicted by the theory when the planes m
96. d allow further work to establish other peripheral projects for the Macintosh family of computers Many of the design projects currently available for the IBM PC and IBM compatibles can now be established or ported to the Macintosh In addition to the project ideas outlined earlier this project can be adapted to test protocols for communi cations experiments between two machines This system can also be useful for other tests wherein the Macintosh SCSI interface is used to host experiments and experimental peripherals L The work in this article is dedicated to Dr Fred Ketterer who teaches electrodynamics electromechanics and digital circuits at the University of Pennsylvania Marc holds a BSEE from the U niver sity of Pennsylvania is currently finishing his MSEE and is pursuing a PHD in Computer Engineering As a communications engineer his special ties include RF communications systems and cellular and satellite communications networks REFERENCES MacArthur Jim Build a Simple SCSlI to Anything Interface Circuit Cellar INK April May 1990 p 15 Eng John Part 1 An Intelligent SCSI Data Acquisition System for the Apple Macintosh Circuit Cellar INK Jung July 1989 p 36 Eng John Part 2 An Intelligent SCSI Data Acquisition System for the Apple Macintosh Circuit Cellar INK Aug Sept 1989 p15 Hodges Mike Part 1 The SCSI Bus BYTE Feb 1990 p 267 Hodges Mike
97. d 50 kHz 300 V electro static transducer and ultrasonic ranging electronics board made by Texas Instruments Sonar Ranger measures ranges of 1 2 inches to 35 feet has a TTL output when operated on 5V and easily connects to a parallel printer port TIO1 Sonar Ranger kit 79 00 plus shipping CHECK OUT THE NEW CIRCUIT CELLAR HOME CONTROL SYSTEM Trainable IR Interface Remote Displays Expandable Network Digital and Analog I O X 10 Interface Call and ask about the HCS HI To order the products shown or to receive a catalog call 203 875 2751 or fax 203 872 2204 Circuit Cellar Kits e 4 Park Street e Suite 12 e Vernon CT 06066 The Computer Applications Journal Issue 37 August 1993 and on Software On Disk for this There must be hundreds more as always your imagination is the only limit to the potential applications for Electronic officer in the U S Merchant Marine for the last 15 years Prior to SOFTWARE 43 DEPARTMENTS 44 Firmware Furnace From the Bench Silicon Update Embedded Techniques Patent Talk ConnecTime 44 Issue 37 August 1993 Absolute Power Corrupts The 386SX Project Gets A Watchdog Ed enters the hardware home stretch as he adds a single chip to handle watchdog functions power monitoring battery control and RAM protection The Firmware Development board is almost ready for action The Computer Applications Journal
98. d by two parameters its magnitude and its phase shift The mathematical representation of the magnitude and phase shift is known as a phasor which is a dimensionless number at DC but has magnitude and phase shift whenever the signal has an AC component Phasor notation provides a simple method of solving tedious algebraic calculations If the product of the open loop gain phasor and the feedback factor phasor equal 1 the denominator of the feedback equation shown above becomes 0 Any number divided by 0 is undefined however we know from calculus that the limit of any number divided by 0 is infinity When the gain of a circuit reaches infinity it will oscillate In phasor notation a quantity with a value of 1 has an absolute value of 1 and a phase shift of 180 The phase shift respon sible for oscillation can come from A B or both The criteria for stability have become rules of thumb For absolute stability the phase shift of the feed back signal should not exceed 120 defined as a phase margin of 60 whenever the gain of the feedback signal exceeds unity Some circuits will never have this much stability Many designs will be stable if the phase shift does not exceed 135 defined as a phase margin of 45 If the feedback phase shift exceeds 180 circuits with gains less than one will Figure 1 n order to mode a simple op amp circuit with single pole roll off special techniques are required
99. d eet ae inverted utofee ase ite inv four at a time by the decoder and sent 15 Error Base 1 3 Read only to the parallel port 16 Init Base 2 2 Read Write BASE 2 control bits The decoder chip U3 is the key 17 Select Base 2 3 Read Write inverted to stable glitch free operation of this circuit Essentially the decoder is set Figure 2 The standard IBM PC printer port connections are fairly well defined All undefined pins should be up with the right address to perform a connected to ground particular function and then strobed by the next computer instruction to execute the function Figure 3 will CTL Port Bits Output to Decoder CTLPort Seq for make decoder operation clear B3 B2 B1BO C302 CI CO U3pin Function Execution 0 1 Y7 EXT_STB_1 gt 4 gt 0 EXT_STB_0 gt 5 gt 1 WRT_LOBYT gt 6 gt 2 WRT_HIBYT gt 7 gt 3 SOFTWARE i RD_NIBL_2 gt c gt 8 0 0 In order to monitor and control all the extra tentacles provided by the Parallel Expander of course the right software is needed Listing 1 shows a few of the routines contained in PARX FAST UN I which is the heart of the software and is written as a Turbo Pascal 6 0 unit The procedures to set the printer port as well as some of the bit setting and RD_NIBL 3 gt D gt 9 RD_NIBL_O A gt E gt A RD_NIBL1 B gt F gt B oooonunui a 1 0 1 0 1 0 1 Figure 3 Each output bit is accessed in a unique way In eac
100. d then B we would get the reverse as shown in Figure 4b By sorting all the objects according to their z depth we can always draw from the back of the list forward In practice the list is kept sorted at all times When an object is transformed using a translation or rotation matrix the object is located in the list and repositioned in the view space accord ing to its new z coordinate BACK FACE REMOVAL Back face or hidden surface removal is performed to save rendering time If we have a cube in our world and we are looking at one of its sides there is no need to render the opposite side of the cube since it will not be seen Back face removal is a simple matter of determining the direction of the vector normal to a particular polygon s surface points If the normal vector has a direction toward the user 14 Issue 37 August 1993 the normal is greater than zero the surface must be rendered If the normal has a direction away from the user the surface can be eliminated COLOR Color is very important for adding another dimension of realism in the virtual world Most renderers have the ability to specify point light sources in the virtual world Each light source will have a direction and a color associated with it As the renderer begins to draw anew screen it will determine how much each of the light sources affects a certain polygon s surface color based upon the angle between the light and the polygon surface
101. e E No Batteries Req d E RS 232 Interface that can t afford a full time engineer venture or just experienced consulting the Ciarcia Design Works is B Easy To Install HB Easy To Use ing staff for once in a while designs ready to work with you Just fax me your problem and we ll be in touch mp A Chip Can you afford not to call today 149 800 274 8699 00 P amp H Remember a Ciarcia design works Call 203 8752199 Fax 203 875 8786 104 10 Issue 37 August 1993 The Computer Applications Journal MICROPOWER A D CONVERTER A micropower A D converter that provides full S bit performance with a 3 volt supply has been introduced by Maxim Integrated Products The MAX152 uses a half flash conversion technique to achieve a 1 8 us conversion time and digitizes at a rate of 400k samples per second A power down feature extends battery life at reduced sampling rates by cutting the supply current to microamp levels The 20 pin SSOP package occupies 30 less area than an Spin DIP To minimize battery drain during burst mode conversions the converter powers down quickly and then powers up again within one conversion period Supply current drops from 15 mA 3mA maximum to 1 pA following a power down command The device powers up in less than 1 microsecond maximum including 450 ps for signal acquisition by the internal track hold circuit The dynamic specifications for the MAX152 include 45 dB minimum S
102. e fixed way for interface projects Everyone is familiar with printers disks tape drives and scanners interfaced through the parallel port Not so familiar but still used are such exotic devices as motor controllers and radiation monitors That s terrific when all you want is the special device connected to the parallel port but no help at all when you want to connect the parallel port to some device or system perhaps several different ones at different times The Parallel Expander is the answer to that problem Five TTL chips and a few connectors provide 16 TTL outputs 16 TTL inputs 2 TTL strobe pulses and an interrupt which 7 DATA OUT 8 c A P A DATA IN 4 R A L L E L CONTROL 4 P O R a INTERRUPT 1 P A R A L L E L E X P A N D E R is a spectacular amount of I O for such a simple inexpensive circuit Figure 1 shows a block diagram of the Parallel Expander interface THE PARALLEL PORT Figure 2 provides the details of the various bits their functions their port assignments and whether or not they are inverted The BASE port is assigned by the operating system to either 02 78H 0378H or 03BCH depending on factors like the type of monitor and the number of parallel ports present A notable feature of the parallel port is that while five bits are available for reading one of these is an interrupt and is reserved for that purpose The remaining four bits hav
103. e RS232 autobaud detect Line printer RS 232 Three8 bit parallel ports EXPANDABLE1 e Compatible with 12 BCC expansion boards To Order Call 1 800 635 3395 Tel 203 871 6170 Fax 203 872 2204 1 89 00 Single oty 199 00 294 00 259 00 CALL FOR OEM PRICING f MICROMINT INC 4 Park Street Vernon CT06066 in EUTOpe 44 0285 858122 1n Canada 514 336 9426 in Australia 02888 6401 abet ined Welcome 119 Pro Log Corporation 2555 Garden Rd Monterey CA 93940 800 5389570 STD bus CPU and I O boards R L C Enterprises 4800 Templeton Rd Atascadero CA 93422 805 466 9717 No bus No DOS 80186 based SBC PC 104 Consortium 990 Almanor Ave Sunnyvale CA 94086 408 245 9348 Fax 408 720 1322 Licensing organization contact for complete list of PC 104 suppliers Saelig Company 716 425 3753 Fax 716 4253835 3 4 x 2 6 PC AT compatible Spectrum Controls P O Box 5533 Bellvue WA 98006 206 746 948 1 Fax 206 641 9473 CPU board packaged with LCD and keypad Radisys Corp 15025 SW Koll Pkwy Beaverton OR 97006 503 646 1800 Small form factor CPU and I 0 modules with rugged packaging STD 32 Special Interest Group 11766 Wilshire Blvd Ste 370 Los Angeles CA 90025 800 733 2111 Fax 800 733 3959 Licensing organization for STD 32 bus designs Recortec Inc 1290 Lawrence Station Rd Sunnyvale CA 94089 408 734 1290
104. e need for designers to be more aware of the special needs of physically impaired users It occurred to me that the vast majority of designers probably are unaware of both the needs of the handicapped as well as recent developments in electronic devices to aid them While this column can do little to rectify the former concern it can bring to light examples of recent develop ments which are of potential value to the impaired As promised in the BBS dialogue here is a whole column devoted to this important topic With luck perhaps it will stimulate some bright designer who will make a worth while contribution In searching the patent database found that patents related to devices for the handicapped seemed to cluster into three general categories those for the physically impaired visually impaired and speech or hearing im paired As the first three patent abstracts show sometimes devices intended for the handicapped may also be applicable to many other areas as well AT amp T s Written Language Parser System in Abstract 1 promises improved speech synthesis quality from freely generated text sequences It goes a step beyond just the synthesis of sounds by applying heuristic processing of the output in order to enhance intelligibility by translating abbreviations and special terms correcting misspellings and noise and changing word emphasis and pauses Abstract 2 which actually covers both patents 4 950 069 and 4 973
105. e one bit inverted and separated from the others These inconsistencies makes for some interesting software gymnastics when reading the bits Another interesting feature is that the control bits BASE 3 are all inverted but one Experiment also showed that these bits do not all change at the same time which can create a potential glitch problem unless considered in the design The Parallel Expander will not work unless all the signals of Figure 3 are present the widespread use of parallel port interfaces however indicates that crippled or oddball ports are very much the exception THE PARALLEL EXPANDER CIRCUIT Figure 4 shows the schematic diagram of the circuit The input is a male DB 25 connector P01 that mates DATA OUT 16 EXTERNAL SYSTEM DATA IN 16 STROBE 2 INTERRUPT 1 Figure 1 A block diagram shows how the parallel expander connects to the PC parallel port and an external system The Computer Applications Journal with the standard parallel port connec tor The data bits are applied to both DB 25 pin Name port Bit Details octal D type flip flops UI and U2 and 1 Strobe Base 2 0 Read Write inverted P 3 la t P by th 2 9 Data0 7 Base 0 7 Write only BASE port ae ea neag a Ime YNE 10 ACK Base 1 6 Read only causes INT if grounded decoding circuit to give 16 output bits 11 Busy Base 1 7 Read only inverted OUT O through OUT 15 The 16 12 PE Base 1 5 Read only PUES ro one S eat i a
106. e way to verify that the watchdog and power monitor code is working so wrote DOGTEST Because the watchdog is active you must boot DOGTEST from diskette so it gets control before the initial 30 second timeout expires it then sets up the interrupt vectors and begins toggling the watchdog output The watchdog doesn t care how often you toggle its input bit as long as you do it often enough If however there s an LED on that bit it is a Very Good Idea to produce a regular heart beat There is something unsettling about an irregular LED even if it does indicate perfectly good code use heartbeat LEDs as output devices a regular blink signifies normal operation while long and short blinks report errors The code is actually pretty straightforward a timer interrupt handler takes care of timing while the mainline code sets up the bit patterns I ve used this trick on many systems so you can probably adapt it to yours Listing 1 shows DOGTEST s timer interrupt handler The mainline code attaches this function tol n t 1Ch which the BIOS invokes after every 54 9 ms timer tick divided that down to 6 bits per second so the interrupt handler runs through the WatchBits variable in about 2 6 seconds The interrupt handler sets Wat ch Flag whenit finishes sending all 16 bits If WatchFl ag is still set The Computer Applications J our nal PC XT AT 386 486 Users 16 BITDATA ACQUISITION Don t Settle Fo
107. ecessary for the creation of sophisti cated virtual worlds and the interac tions in these worlds U In addition to being the publisher of PCVR magazine and the Director of Software Development at VRontier Worlds of Stoughton Inc Joseph holds a Bachelor s degree in Computer Science and is currently working on his Master s degree in Computer Science SOFTWARE Software for this article is avail able from the Circuit Calar BBS and on Software On Disk for this issue Please see the end of ConnecTime in this issue for downloading and ordering infor mation CONTACT Those interested in more information about Homebrew and Low End Virtual Reality Technology are directed to PCVR P O Box 475 Stoughton WI 53589 Phone fax 608 877 0909 More information on Power Glove Interfacing and sources can be found in the July 1990 issue of Byte magazine 401 Very Useful 402 Moderately Useful 403 Not Useful The Computer Applications Journal RELAY INTERFACE PROVIDES SOFTWARE CONTROL OF RELAYS 3 i CONNECTS TO RS 232 AR 16 RELAY INTERFACE r Two 8 channel relay output ports are provided for control ol up to 16 relays expandable to 128 relays using EX 16 expansion cards Each relay output port connects to a relay card or terminal block A variety of relay cards and relays are stocked Call for more info RS 422 available distances to 4 000 feet PS 4 port selector may be used to control satellite AR
108. econd option works well when the object is quite complex and real three dimensional views of the object are needed in order to perfect it The last option is the most attractive because there is no sense in reinvent ing the wheel when somebody else has already done it There are many objects already in the public domain that can be used to create a virtual world using the renderer For my example am going to use a public domain object and explain its features and how it was created Figure 5 shows the printout of my tree object After any optional header information comes the actual points or vertices used in the creation of the objects These vertices are based in the three dimensional coordinate system and are separated by spaces i 8048 8085 8096 Hitachi lt In Circuit Emulators 16 Issue 37 August 1993 The Computer Applications The vertices are followed by information about the polygons that make up the object As stated earlier the renderer uses polygons to represent objects just as they are defined in the object files themselves Polygons can have from three to n vertices For the object file each of the polygons must be defined from the vertex list defined at the beginning of the file The polygon definitions each begin with the color of the polygon to be defined This number is followed by the total number of vertices that make up the polygon Next comes the index number of each of the vertices
109. ectable RS 422 ports TOUCH TONE DECODER and other serial interfacing products available Call for free intormation packet FULL TECHNICAL SUPPORT Provided over the telephone by our staff EACH ORDER INCLUDES A FREE DISK WITH PROGRAMMING EXAMPLES IN BASIC C AND ASSEMBLY LANGUAGE A detailed technical reference manual ts also included HIGH RELIABILITY engineered for continuous 24 hour industrial applications All ICs socketed Use with IBM and compatibles Tandy Apple Mac and most other computers with AS 232 or 422 ports All standard baud rates and protocols may be used 50 to 19 200 baud Use our 600 number to order FREE INFORMATION PACKET Technical Information 614 464 4470 F HOUR ORDER LINE 800 842 7714 International amp Domestic FAX 614 464 9656 Use for information technical support amp orders ELECTRONIC ENERGY CONTROL INC 380 South Fifth Street Suite 604 Columbus Ohio 43215 111 Issue 37 August 1993 1 9 Oscillators Dont Amplifiers Do 20 A problem common to any analog circuit that uses feedback is unwanted oscillations due to an unstable design Automated tools can help point out a circuits weak spots and often suggest a course of action Issue 37 August 1993 FEATURE ARTICLE Mark Nurczyk P E he title is a tongue in cheek saying that has been round for as long as have been involved with electronics Unintended oscil
110. ed temperature opera tion those values are for real BACKUP WARNING Although we ve all seen and used the canonical diode and battery backup power circuit there are good reasons to make things a bit more complex decided to use the vener able MAX691 because it has power monitoring battery control RAM protection and a watchdog timer in a Issue 37 August 1993 45 Cc 53 O D Q Q u _ D z O a Voltage on pin 20 CE Figure 3 The CE input voltage affects the current drawn by a static RAM when Vecis 5 volts but a similar curve applies for 3 volt battery backup operation The CE input must be within a few hundred millivolts of Vec to put the RAM into standby mode The 54 mA spike which goes off the vertical scale at 1 3 volts is caused by the chip s infernal logic passing through the range where both the p and n channel FETs conduct current single IC Other parts may be better for your particular application but the 691 is a general purpose workhorse Figure 4 shows the minimal external circuitry most of the gates drive indicator LEDs that you might not need in a production system favor lots of LEDs to indicate what the firmware and hardware are up to but after all this is a demo system Battery backup is straightforward because the MAX69 1 switches the voltage on pin 2 to the higher of the power supply on pin 3 or the battery on pin 1 used a 3 volt 250 mAH lithium cell but
111. een The faster the line drawing routines the faster the renderer can update the screen after some user input The majority of this code can be written in highly optimized assembly language to take advantage of specific hardware However this limits the portability of the code which serves to keep the prices of rendering packages high PROGRAMMING A VIRTUAL WORLD In this section use the PCVR Renderer a rendering program that is being developed and described in PCVR magazine to develop a Virtual World that consists of a grove of trees The first step in creating a new virtual world is to draw the proposed world from an overhead two dimensional view This view gives me an idea of the scale want to use when placing the trees The next step is to place the objects in the world using the standard three dimensional coordinate system Using these preliminary setup steps allows me to see where the objects will be in the new world and the distances between them After have placed the objects have to design each one of the objects There are several different ways to develop objects Create object by hand Create the object using Computer Aided Design software Use a public domain object The first option create by hand relies on your ability to do three dimensional art on a two dimensional drawing pad This option is good for very simple objects that contain boxes triangles and other rudimentary shapes The s
112. efer to Figure 2 for more details of the bq2003 s actual charge sequence LINEAR CONSTANT CURRENT As you know the bq2003 can be configured to generate charging current using its built in buck type switch mode controller Although much more efficient than a linear current source it is admittedly more expensive to put together For rela tively low charging currents a linear constant current source usually works fine Nonetheless it s wise to consider the current and power requirements along with the prevailing thermal issues before erring on the side of simplicity When the current require ments fall below a certain threshold the choice becomes much more clear cut and safe Utilizing the flexibility of the bq2003 you can still enjoy the benefits of the superior delta temperature delta time and negative delta voltage charge termination mechanisms while using a simple and cheap linear constant current source The bq2003 s cost feature ratio can easily justify using only a portion of its capability Of course the safety backup and charge disable functions along with the discharge before charge capability are still available even if you decide to go with this simpler configuration Referring to Figure 3 you can see by connecting SNS to ground MOD gates an external current source for the duration of the charging sequence until a terminating event is detected In this arrangement taking MOD high turns Q2 on which
113. el interface resides on a breadboard connected to the SE via the Small Computer System Interface SCSI port The SCSI protocols virtually demand that the target device on the SCSI bus contain a microcon troller or some embedded logic to participate in the control of the SCSI bus The system present here will support embedded controllers attached to the Mac since it is designed to allow the Macintosh to download code to a microcontroller or a PROM during testing and development of your peripheral The SCSI blind interface describe here can be used as a gateway to a Macintosh host You can attach functional modules to this port to produce the following peripherals EEPROM programmers Microcontroller development systems The Computer Applications Journal General data collection devices Control systems Here is a Suggested order of attack to implement an embedded controller attached to the Mac via the SCSI bus Create the prototype of the intelligent target Write a downloade program mer for a microcontroller or PROM Write a SCSI bus control program for the interface For the balance of this article l Il assume that the breadboard is the only target device on the SCSI bus and that all data to be downloaded to the target resides in the Macintosh s RAM or on a floppy diskette The machine s hard drive cannot be accessed because it too is connected to the SCSI bus And since the target is not intelligent eno
114. esolution of these sensors seems to be a 2 mm minimum space or mark This can be improved slightly using a slotted mask at the focal point that does not allow adjacent marks from interfering with the total reflec tion Next month l Il investigate trading cost for higher resolutions as well as adding some smarts to the Swipe reader a 135 Real Time Imaging with Display Output 8 Bit 256 Gray Levels Jeff Bachiochi pronounced BAH key AH key is an electrical engineer on the Computer Applications Journal s engineering staff His background ar our cross includes product design and manufac turing compilers so Inexpensive SOURCE Digi Key Corp 701 Brooks Ave South Thief River Falls MN 56701 0677 4 G aa a 3380 We base our cross compilers on the GNU C C compiler from the Free Software Foundation We provide you with one year of Because we give them away free SOFTWARE support and give you a ready to run cross compiler with complete ae des source for DOS Windows OS 2 2 0 or UNIX for 495 per year Software for this article is avail 9 h tended t k for 895 hich clad able from the Circuit Calar BBS r get the extended support package for which includes and on Software On Disk for this GNU Emacs and make the CVS and RCS source code control issue Please see the end of utilities and the T X typesetting system Targets include i386 ConnecTime in this issue for 1860 1960
115. et again don t remember but think the difference was on the order of 10 second Also you can t really call these effects errors The clock is accurately measuring the passage of time it just isn t necessarily the same amount of time as at Ft Collins If you want to know what time it is in Ft Collins call up NIST read A Brief History of Time but don t recall the comment about satellites don t agree with the you can t have satellites comment the frequency errors introduced by relativity are many orders of magnitude smaller than the Doppler shifts caused by the motion of the satellite in relation to the Earth even geosynchronous satellites move around Ground equipment is designed to handle this Msg 11936 From TERRY NORRIS To DAVE TWEED think finally found something that talks of my question But first an explanation or shall say apology Hawking didn t say it was impossible for satellites he just said the differences could cause calculations of positions to be miles off fifth paragraph from end of chapter 2 Another You are most decidedly correct when you said the correct term should be differences Oe TIME Anyway the answer was in an astrophysics book The explanation is simple but the equation is even simpler dt SQRT 1 2MG rc dto dto is the interval between ticks of a standard clock as measured by a distant observer M mass G the universal gravit
116. fact that Power Good C WDZ clear says leave the output high i D AX WATCHDOG_A set says make output low was active long after the power went UT DX AX sand t oii bad argued in vain for a power XOR AX WATCHDOG_A flip the bit back again monitor chip but the board was OV CtIisCopy AX save for next time already laid out and it was easier to joken POP ane restore bystanders kludge the cap than add an IC T POP DX The MAX691 monitors the supply POP AX voltage on pin 3 and triggers several POP BP actions when it falls below specific RET restore stacked flags levels While these may not be strictly necessary in a PC with a good power supply as long as we re using the chip we may as well put it to good use If 48 Issue 37 August 1993 The Computer Applications our nal for whatever reason you are net using a standard PC supply this circuit will ensure that the RAM s contents are intact regardless of what happens to the rest of the system Recall that we must put the RAM into standby mode when the power fails The MAX69 I s CE Out signal tracks CE In until the supply voltage falls below 4 65 volts at which point the MAX691 forces CE Out high This disables the RAM and puts it into standby mode Unfortunately while the MAX691 s nominal delay is 50 ns from CE In to CE Out the maximum is 200 ns That s OK for this relatively slow ISA bus application but fat should show how to adapt it to faster systems
117. for the cross connection and the third one tied together for the clock used an optocoupler to provide the basic zero detec tion or actually the signal polarity detection fed the output to an XOR directly to one input and through a 0 1 ms RC time constant filter to the other input Got 0 1 ms narrow pulses on every zero crossing Msg 11915 From LARRY G NELSON SR To GREG PRICE How about a Motorola MOC3011 or similar These are optoisolators with zero crossing detect and triac output Not sure the exact part number you would want but this could be the ticket for what you are looking for Automotive EMI can be a drag Msg 15175 From PAUL CONLIN To ALL USERS am looking for some assistance on an embedded microprocessor data logging system think electromag netic interference is causing havoc with the micro The system is a handmade prototype of an on board automotive data logging system based on the Motorola 68HC11 The environment is particularly brutal vibration extreme acceleration and what may be extensive interfer ence from the engine s ignition system The target application is a very high output super charged drag race car using a magneto based ignition with mechanical distributor The high boost pressures present very high cylinder pressures The voltage requirements to ionize such a spark plug gap must be very high The data logger consists of a HC1 1 E2 1M DRAM RS 232 level buffer signal conditio
118. gation Using sonar echo principles much like that found on Polaroid cameras a narrow beam of ultrasound presumably emanating from the user s cane may be directed at objects in any direction and provide the user with an indication of distance to the object As with all human aids the man machine interface direction indicator in this case is crucial to the success of the concept A review of the complete patent should provide specifics in this area The patent described in Abstract 5 promises to aid the travel of blind individuals through the use of a radio frequency message apparatus Basically a low power portable radio transceiver carried by the person is enployed to query any number of distributed base transceivers The base unit within range responds by sending a canned 3 704 345 4 278 838 4 674 065 4 831 654 4 868 750 4 872 202 4 873 634 4 975 957 4 996 707 An enhanced text to speech synthesizer accepts freely generated text sequences of words and synthesizes the received sequences with proper emphasis and with properly placed pauses In combination with other elements the synthesizer provides for an enhanced Dual Party Relay Service where the text generated by the sound impaired party is synthesized without an attendant s intervention The text generated by users is made more intelligible by interpreting abbreviations correcting errors misspellings and noise translating special terms that are used by the communit
119. h case set up the decoder with B3 B1 and BO Then raise B2 to execute the function same as adding 4 Finally lower B2 to end the execution testing routines are in Pascal The moe aa eI E PO3 DB 25 critical routines shown in the listing 13 SELECT Ja ETA a a a i Manara are in assembler which dramatically y i ay inaia increases the speed and reduces the Pee 74 8974 rog ey C OUT 7 t P cee size of the code OUT 68 We 16 eee OUT 5_ 18 Refer to Figures 2 and 3 when out a e eae OUT 3_5 reading the assembler code the tables tH 7 QuT 2 4 v ys J ae OUT 1_3 will help you understand how the Es ee 2 ne K OE Q ee ee Aig software deals with the gap in the us input bits and the addressing and Ls244 Pe3 strobing process for the decoder Note ies IN osts that all 1 O is done 16 bits at time It s ie f Jen meat ma Sane P 2 DB 25 aya Inor E not much trouble to change this for 18 fop 190UT 15_ 25 IN 02 lt 5 fast 8 bit I O the code is already ia 79equraia 34 TH 00 2 therejust rearrange it eh Sts our 11 eg ae 4 z roe INT The software should be very easy aor ours is ee OUT 8 18 P 4 DB 9 to recast in all assembler C other anpli versions of Pascal or BASIC would expect however that using interpreted BASIC will cause a drastic slowdown a YS YI ve va VE es in execution F usias vsp 6 7 A B C G2A M 16 10 14 12 13
120. hat pin 20 is at 4 8 volts when pin 28 is at the normal 5 volts but can be 2 8 volts when pin 28 is driven by a 3 volt lithium cell Figure 3 shows the result of a simple experiment measuring supply current as a function of CE voltage The vertical axis uses a logarithmic scale to compress the current but it s easy to see when standby mode kicks in at about 4 5 volts ran the RAM at 5 volts but the results are similar at 3 volts To ensure that CE is held at the right level you must drive it with a CMOS gate Ordinary TTL gates cannot pull the input high enough draw too much current for battery operation and don t run at 3 volts anyway The output from a CMOS gate is nearly at the supply voltage and will track the power supply as it switches to battery backup The spike at 1 3 volts exceeds 54 mA and occurs when the chip s internal logic passes through the range where both the p and n channel FETs conduct current This is why you put lots of bypass capacitors on logic supplies and is where all the digital noise on your circuit board comes from The RAM s current draw has an exponential relation to chip tempera ture so it may vary by nearly three orders of magnitude over the full temperature range My graph repre sents room temperature but found that could double the supply current by parking a desk lamp over the RAM chip Pay close attention to the spec sheets when sizing the battery if you need extend
121. he high temperature cutoff is set to 50 C The charging prequalification param eters configure the low temperature The Computer Applications Journal fault to 10 C with the high tempera ture fault set to 47 C Not shown are the connections to TM1 and TM2 the safety time hold off interval top off selection pins as well as the value for the trickle current resistor R10 Select R10 for the trickle current rate that meets your particular application Note that the trickle resistor serves two purposes in the charging system As you d expect it supplies a small trickle current that provides a charge sustaining current once the fast Issue 37 August 1993 71 charge cycle completes It also sources the current required to condition a deeply discharged battery prior to the application of a fast charge The second usage of the trickle resistor is to provide a high voltage supply that is used as a reference which allows the bq2003 to detect a battery insertion Incidently if you set up the chip to use the top off feature that delivers charging current at a reduced duty cycle 1 8 the fast charge rate the trickle resistor can be a fairly large value since it will only have to put back the energy lost to self discharge You may wish to keep this fact in mind when working with NiMH batteries because they are less tolerant of overcharge than NiCd types When selecting the main power supply make sure to account for the voltage
122. he Earth s motion and this fact made the Earth s motion measurable Silvertooth measured the 378 km s motion of the Earth in this experiment Some references are Silvertooth E W Experimental Detection of the Ether Speculations in Science and Technology vol 10 no 1 page 3 1987 In that same issue beginning on page 9 is an excellent plain English sum mary by H Aspden entitled On the Silvertooth Experi ment by Erol Torun 7 20 92 from the KeelyNet BBS We are heading toward the constellation Leo The Computer Applications Journal Issue 37 August 1993 85 HOS TIME Someone always says that relativity disproved the aether of old Maybe it did disprove the static aether of old Today s aether is considered a dynamic sea of energy in the flux of the vacuum Sea In Which The Earth Floats Dirac Sea Neutrino Sea and so forth of quantum physics l Il leave you with this The following statement would be considered heresy by the relativity crowd but take note of who said it According to the general theory of relativity space without aether is unthinkable for in such a space there not only would be no propagation of light but also no possibil ity of existence for standards of space and time measuring rods and clocks nor therefore any space time intervals in the physical sense Albert Einstein from an obscure speech in Leiden Germany 1920 Did you catch the name there
123. he desired SCSI register Then set the data lines with the information to go to the register Enable the chip by bringing CS low Finally ensure RD is high and pulse WR low to transfer the data into the register In terms relevant to the SCSI bus standard the initiator is a device that assumes control of the bus There can be only one initiator at any given time The target is any other peripheral connected to the bus The SCSI standard allows up to seven target devices and one initiator on each SCSI bus vec Ag wR RESET EOP DAK READY RD INT DRO cs PERERRRERER These data liner plus DO pin 1 interface to the computer or devices under development test For my project l Il assume that there is only one target connected to the bus the breadboard with the initiator being the Macintosh This assumption allows me to use the SCSI interface without having to select which of the seven possible target peripherals is desired By assuming that the breadboard is the only listener on the bus can have more control over how manipulate the data and control lines My entire test bed is illustrated in Figure 3 In the final version of this project all the register manipulations neces sary will be carried out via the com 74LS240 20 individual display indicators are connected to these lines Don t forget to connect D pin 1 and skip UCC and GND lines Figure 2 The SCS control data indicator
124. he second piece pressed loosely against the first When acard is inserted between the first and second piece the spring s tension holds the card against the guide at the appropriate distance from the sensor Figure 1 shows how the card guide is assembled SENSOR SELECTION The reflective photomicrosensor system uses an infrared light source and a phototransistor diode to pick up the reflected light energy These devices are available separately or packaged together as a photosensor Photosensor housings aim the light source and sensor such that they converge at a predetermined distance or focal length The reflective surface should be placed at this distance for maximum sensitivity Two such photosensors available from Digi Key are the EE SY101 and EE SY148 both made by Omron The 101 is a TO 92 sized device with a focal length of 1 mm mounted these along the edge of a small piece of protoboard Refer to Figure 2 for the circuit used to support these photomicrosensors The comparator has an adjustable trip point POT1 and hysteresis POT2 The output of the circuit is forwarded to a four pin connector that provides connection points for both power and the conditioned sensor outputs J1 5 Top Track Bottom Track Ground Figure 2 A photosensor package EE SY101 consists of a reflective photomicrosensor which uses an infrared light source and a phototransistor to pick up the reflected light energy The Co
125. hed on to the concept and blown it out of proportion Find out what low cost VR really is The Computer Applications Journal ince the release of the motion picture The Lawnmower Man everyone has become obsessed with the technology of Virtual Reality VR While VR is just making its way into the mainstream it has been around for many years In this article I ll explore the topic of Virtual Reality using an IBM compatible personal computer WHAT IS IT Many definitions have been given for Virtual Reality by press and industry figures However feel the most accurate definition for VR is an interactive three dimensional play ground Using a computer attached to some specialized hardware that s running some clever software a VR user is put into a virtual world built from the developer s imagination The software represents the visual aspects of the virtual world as a number of shaded polygons that may or may not have visual textures or other at tributes In the most rudimentary systems the user wears a pair of shutter glasses which block one of the eyes at the same time an image is flashed on the screen The glasses cause the images on the monitor to appear three dimensional The user can upgrade to Figure 1 Typical renderers take in raw numeric data and create solid objects wih proper perspective to give the illusion of fhree dimensions head mounted display hardware to enhan
126. ht identify the location of the base unit would actually be more useful in practice In general it is by street intersection or landmark for example It occurred to me that such a unit might naturally be incorporated within a traffic light design Located there is the needed operating power an excellent line of site RF position a natural location at intersections and space to house the transceiver Another device which is actually designed to be located within the traffic light is the tactile crossing signal indicator of Abstract 6 The purpose of this aid is to let the user know when it is safe to cross a street at an intersec tion While the abstract concentrates more on the tactile indicator design could envision the indicator using instead the same type of canned message audible response as in the foregoing abstract But it would take a blind user to say which of the two types of response mechanisms crucial to involve the handicapped user community in the design of a successful aid It would also seem that there is no real need for two way communications A simple inexpensive low power transmitter incorporated within the traffic light could broadcast its street intersection informa tion along with the traffic signal status If this were in the form of audible information it might be possible for the blind user to employ nothing more than a conventional broadcast radio tuned to a specific channel believe the more that c
127. iCd battery to varying depths of discharge prior to charging helps to inhibit the voltage depression effect better known as memory effect Discharge before charge most frequently involves taking the battery down to its end of dis charge voltage which most of the time is immediately followed by the initiation of the charge cycle Pulsed charging where a slug of current is followed by a rest period provides more efficient charge reac tions than continuous constant cur rent charging For example using a 2 second interval you could hit a 1 AH battery capable of withstanding a 1C charge rate with a 2 amp current for 1 second followed by 1 second of rest time The effective charge rate there fore would amount to 1C The heavier current ddivery could in this case improve the charge efficiency by up to ten percent over continuous charging Issue 37 August 1993 73 Dd REGULATED 1N4001 oc R10 TRICKLE RESISTOR DAA RIG 1 02 gt DL F 1N4148 06 1N5400 cemo vec H Le DCMO DIS ul 802903 1 3 14 DVEN MOD rm2 TEMPE 8 1k AMY 2 R9 ik nonea M 4 TMI CHG 7 3 HLMP4700 D Sits MCU BAT TCO 2 uss SNS Figure 3 The bq2003 circuit can drive an LM317 to provide The rest period allows for cooling and for passive electrolyte depolarization Depending on how much current you pulse into the battery
128. iNAD and 50 dB maximum Total Harmonic Distortion THD Its microprocessor interface appears as a memory location or I O port and requires no external interface logic The data outputs use latched three state buffered circuitry for direct connection to a TATE e a eee NEWS microprocessor data bus or system input port Vin and Vref terminals allow ratiometric operation The MAX152 sdls for 4 25 in quantity Maxim Integrated Products 120 San Gabriel Dr Sunnyvale CA 94086 408 737 7600 508 EASY TO USE SINGLE BOARD COMPUTERS With EMAC s feature packed Single Board Computers and easy to use BASIC compiler your application product can become a reality in no time EMAC s BASIC compiler can process real time interrupts fron a number of sources easily and efficiently Multitasking allows your programs to do several things all at the same time with no hassles Built in networking allows your system to grow as you do Drivers for all of the VO devices serial ports A D inputs D A outputs timer counters digital O RTC are built into the BASIC making H themextremelyeasytouse If BASIC is not your language of choice EMAC offers Assembler ANSI C and Forth you choose So take one of our single boards computers for a 30 day risk free test drive and just see what it can do for you EMAC s single board computers start at 249 00 for the EPAC 3000 shown above elnaAc INC 618 5294525 FAX 618 45
129. ide charging current LED drivers for displaying battery and charge status are built into the device A single LED shows events such as charge pending discharge fast charge in progress charge complete and charge aborted They pack all of these different status indications into a single LED by driving it using a varying duty cycle sequence of on off pulses This kind of approach when taken to extremes can degenerate into The Computer Applications ournal an incomprehensible rash of gibberish that ultimately conveys nothing In this usage howeve it is not a prob lem at all to decipher the status being conveyed since only a few different and rather distinct patterns are issued Take this courteous treatment of the end user as an object lesson in judicious restraint and good design practice Temperature status is also shown using a separate LED that indicates an out of range temperature when it is illuminated In an attempt to clarify the bq2003 s operation let me begin with an overview of the IC s pin functions presented in Figure 1 Charge action is controlled by inputs from the CCMD charge command DCMD discharge com mand and DVEN negative delta voltage enable input pins and the TM 1 and TM2 failsafe timer initial hold off interval top off enable programming pins Charge initiation is qualified by two factors First the battery temperature must be between the low temperature fault and high temperatu
130. ie in the left half of the complex plane the circuit is stable Correct circuit evaluation is possible with all of the above methods They are tedious and require the circuit designer to have a great deal of skill The advent of the personal computer has produced easier faster methods The easiest way to deter mine circuit stability is to use a circuit analysis program such as PSpice by MicroSim The student edition of PSpice contains an AC analysis that determines both magnitude and phase at any frequency An AC voltage source placed in your circuit s feed back path and swept over a large range of frequencies can show where the circuit is potentially unstable The circuit you are most likely to check for stability will probably involve an op amp so an accurate op amp model must exist before a stability analysis can be performed The student edition of PSpice has some restrictions on circuit size the models for dements such as op amps must be relatively modest but they can still contain enough information to be useful Figure 1 shows a simple op amp model with a single pole roll off Generally speaking complex parts such as op amps require special modding techniques To simulate correct circuit performance input impedance frequency response slew rate voltage gain and output param eters all have to be specified Ryn is the op amp s input imped ance as defined on the data sheet for the device and is connected t
131. in defin define main0 EventRecord event printf SCSI test i printf This progra while Get result SCSIReset TestResult printf Click mouse while Get asm Debugger MOVEA L A7 LINK OVEM L OVEA L OVEA L LEA A0 D2 D7 A2 A SCSIBase A SCSIGlobal sWrICR A3 sl Set the BSY lin accessing the Initiator The required bit chip 0x0C00 OxO0COC 0x0201 0x0260 Output Data Curre SCSI Output Data Curre SCSI 1R Data LX itiator i Register 2 ras Comma Le Enable DMA Send DMA Target DMA In SCSI itiator Co ies egister 2 7 Comma X SCSI Bus and Status JE Data Regi Dat Regi Dat Regi Dat 0x0010 0x0020 0x0030 0x0040 0x0050 0x0060 0x0070 Bus Input Reset Click mouse to Macsbug be n Progress m requires Jg to continue nUse s to Invoke Macsbug debugger A6 OXFFF8 4 A7 3 SCSIBase s A4 AO Set AQ to sl nitiator e to active low This line Command Register setting is the 4th b SCS WR Test iator HA 1 of Code ster with RACK a with DACK ster with DACK a with DACK ster Command Register d Register Register Receive Receive a mand Register d Register Status Resgister Register Parity Interrupt continue n n installed n n extEvent mDownMask keyDownMask amp event the step n extEvent mDownMask
132. inactive and holds it until the disk boot is finished As a result just after reset the watchdog must allow about 20 seconds for the system s normal boot process But a 20 second timeout is probably far longer than you re willing to wait when your firmware should be in control so we need a variable rate watchdog I ve seen some systems that allow you to disable the watchdog but don t like that because a firmware fault or hardware glitch can nay will find that chunk of code and disable the watchdog just before taking a perma nent walk in the woods A variable rate watchdog ensures that the reset will occur eventually Figure 4 shows how adapted the MAX691 s watchdog The LS74 flip flop is cleared by the ISA bus RstDrv signal When the MAX691 s Osc Sel input is low its watchdog runs at a frequency set by the external capaci tor In this case the 1 nF cap sets a watchdog timeout of about 30 seconds which is long enough to load and start a program from disk The first time the code writes to port 3 1 C on the Firmware Develop ment Board it sets the flip flop which raises both Osc Sel and through the diode Osc In When those inputs are high the MAX691 runs from an internal oscillator that causes a time out after 1 6 seconds which is fast enough for normal operations The MAX691 data sheet has formulas to compute the external capacitor value for a given timeout but I ve found that they are not parti
133. ing in a room and wondering who is knocking on the door Instead of opening the door you simply change viewpoints to outside the room to see who is knocking ONE OR TWO EYES Finally when a user is using just the computer screen to view a virtual world they see a single image of the screen This is called monoscopic presentation The renderer draws a single image of the objects in the world on the computer screen and the user relies on human ability to bring out the depth in the image The developer of this world helps to facilitate the depth by using the perspective view technique and making farther objects smaller than objects that are closer to the user To better achieve the true sense of three dimensions a user can wear shutter glasses or a head mounted display When these pieces of equip ment are used the rendering software must generate two separate views of the world One of the views is for the left eye and the other is for the right eye This is achieved by moving the viewpoint of the user a little to the left and generating an image then moving the viewpoint a little to the right and generating an image Depending on the hardware used each of the images is presented to the appropriate eye and the user sees a true 3 D image CONCLUSION In this article touched on the hardware and software necessary to bring Virtual Reality to the IBM compatible personal computer user The renderer provides the capability n
134. ing information such as the streets of an intersection at which the base unit is located The portable transceiver has a limited transmission range of prefer ably about 20 50 feet to enable it to interrogate a single base transceiver unit located at an intersection within a metropolitan area or at a display exhibit within a recreational facility such as a zoological park without acciden tally interrogating base transceivers in the near vicinity of the desired base transceiver In a preferred embodi ment an electronic compass is included within the portable transceiver to further aid a visually handicapped individual in orientating himself herself with respect to North South East and Westerly directions 5 103 223 1992 04 07 Humphrey Jerry J CA 494 337 2 461 448 2 754 505 4 139 742 4590 474 4 635 287 4 851 836 Street crossing signal A street crossing signal for the visually impaired is disclosed The signal acts cooperatively with the traffic signals to provide a tactile indication of the proper time to cross a street A vibrator unit is retained relative to a panel having an indicator window there through which allows contact with the vibrator unit The vibrator unit is retained relative to the panel and frame so that vibration of the unit is not transferred to the panel or the frame Relatively straightforward electronics make up this device showing that such aids need not be overly complex Finally the electrotactile vocoder
135. ions under MS DOS with RTKernel RTKemel is a professional high perlormance real lime multitasking kernel It runs under MS DOS and supports Microsoft C Borland C Borland Turbo Pascal and Stony Brook Pascal RTKernel isalibraryyoucanlinktoyour application It lets you run several C functions or Pascal procedures as parallel tasks RTKernel offers the following advanced features pre emptive event interrupt driven scheduling number of tasks only limited by available RAM e task switch time of approx 6 psecs 33 MHz 486 performance is independent of the number of tasks use up to 64 priorities to control your tasks e priorities changeable at run time time slicing canbe activated programmable timer interruptrate 0 1 to55ms high resolution timer for time measurement 1 psec e activate or suspend tasks outof Interrupt handlers programmable interrupt priorities inter task communications using semaphores mailboxes andmessage passing keyboard harddisk and floppy disk idle times usablebyothertasks Interrupt handlers for keyboard COM ports and network interrupts Included with source code free technical support by phone or fax g RTKernel C SC 6 0 7 0 8 0 BC 1 0 2 0 3 x 495 Source Code add 445 b a RTKernel Pascal TP BP5 x 6 0 7 0 SBP6 x 445 Source Code add 375 For international orders add 30 for shipping and handling MasterCard Visa check bank transfer COD accepted Sa eee METS
136. ischarge FET control output An active high push pull output used to turn on an external transistor to discharge the battery through an external load before charging Temperature status output An active low push pull output that indicates when the battery temperature is not within the acceptable range to initiate charging Charging status output A push pull output used to indicate charging status Timer mode inputs These three level inputs control the settings for the fast charge safety timer initial termination monitoring hold off interval and select the top off capabil ity Current switching control output An active high push pull output that controls charging current to the battery Charge current sense input This input controls switching of MOD based on an external sense resistor If SNS is connected to VSS external current source mode MOD switches high at the start of the charge cycle and low at the end of the cycle Figure 1 The bq2003 handles a number of different charging schemes plus provides feedback to the user of current charge and temperature status brute force configuration you must watch your power Charge can be initiated on battery replacement or by VCC going valid In this particular arrangement negative delta voltage detection is enabled DVEN high and discharge before charge is disabled DCMD low The delta temperature delta time threshold is set to 1 04 C per minute and t
137. lations are possible whenever you design high gain analog circuits The fear of oscillation paired with little known analog design techniques keep many engineers from designing analog circuits The simple techniques develop here will help you get over that fear so you can begin to design stable analog circuits Why do amplifier circuits oscil late Feedback Analog circuits often use negative feedback to produce predictable circuit performance Negative feedback works by imparting a phase shift to the feedback signal of 180 With negative feedback the drcuit will have a predictable closed loop performance If the feedback network or the amplifier adds an additional 180 phase shift the feedback will change from negative to positive With positive feedback the circuit will oscillate when the gain of the circuit exceeds unity The follow ing classic feedback equation shows why circuits oscillate Aa Aa Ty Ay xB A Cclosedloop gain Aj 0pen loop gain B feedbackfactor The closed loop gain is the actual gain produced by the amplifier and its feedback network The open loop gain is the raw gain produced by the amplifier element of the circuit For many common op amps the open loop gain is approximately 100 000 The feedback factor is the reciprocal of the feedback network s transfer function All three elements of the feedback equation are phasors At a given frequency any voltage or current is characterize
138. ld even be inclined towards surface mount I usually am gt as this gives a significant decrease in size and contact resistance Msg 15229 From J IM WHITE To PAUL CONLIN I empathize with the difficulty of your task devdoped the TachTale system and had my share of grief confronting the dirty world of racing with electronics never tried putting TachTale on a drag racer Kenny Bernstein s operation is just down the street and they seemed to havea pretty strong market position have had some experience with high impulse igni tions but not the dreaded magneto and there is good news and bad news The bad news is that it is not practical to keep out all the induced noise The good news is that you may be able to keep the noise low enough to operate A working system will almost certainly have to attack the problem from both sides Keep out as much of the EM1 as possible This includes maximum feasible shielding Consider Numetal or other materials which provide magnetic as well as electric attenuation Certainly shield the electronics a plastic case a few feet from a magneto and ignition wires is bound to be less than optimal Remember that the sensor wires are terrifict antennas and their shielding is not perfect either The other half of the equation is to make your elec tronic design as noise tolerant as possible Some of the relevant techniques include the use of all CMOS logic which is more noise tolerant than TTL
139. le Cove Rd N Billerica MA 01862 508 663 2070 Fax 508 663 5094 Passive backplane CPUs I O boards and packaging Ampro Computers Inc 990 Almanor Ave Sunnyvale CA 94086 408 522 2100 Fax 408 720 1305 PC 104 CPU and I O boards Analogic Corporation 360 Audobon Rd Wakefield MA 0 1880 508 977 3000 Fax 617 245 1274 Passive backplane 1 O boards and packaging Annabooks 15010 Ave of Science 101 San Diego CA 92128 619 673 0870 Fax 619 673 1432 Embedded PC documentation and training APPRO International 3687 Enochs St Santa Clara CA 9505 1 408 732 6091 Fax 408 732 6095 Passive backplane CPUs I O boards and packaging Automated Control Concepts 3535 Route 66 Neptune NJ 07753 908 922 6611 Fax 908 922 9611 Passive backplane system with steel NEMA 4 12 packaging Azimuth Technologies 6 Landmark Sq 4th floor Stamford CT 06901 203 359 5706 Passive backplane 486 system and rack mount packaging Computer Boards Inc 44 Wood Ave Mansfield MA 02048 508 261 1123 Fax 508 261 1094 Analog and digital O boards Opto 22 interface and racks Computer Dynamics 107 S Main St Greer SC 29650 803 877 8700 STD bus and stand alone PC compatible SBCs CyberResearch Inc P O Box 9565 New Haven CT 06535 0565 203 483 8815 Fax 203 483 9024 Passive backplane CPUs I O boards and packaging Daisy Data Inc 333 South En
140. like two more RS 232 422 485 ports 24 more digital I O ports Real Time Clock EEPROM and battery backup for clock and RAM right on board Start with the Develop ment board it has all the peripherals plus a debug monitor for only 349 Download and debug your code right on the SBC then move to the OEM board above for your production needs We also do custom design work call for our reasonable prices New 8051 Pany Emulator Support Our DryICE Plus product has been expanded to include support for the Siemens 806537 The base emulation unit is still only 299 with the 80C537 pod priced at 199 Other 8051 family proces sors supported are 8031 32 80C31 32 8751 52 87C51 52 80C154 800451 80C535 80C552 562 80C652 a n d 80C51FA B C Each of these pods is priced at 149 Where else can you getan emulator with this much power and flexi bility for only 448 complete Our original stand alone 8031 ICEis still priced at 199 Though not as flexible as the DryiCE Plus it offers excellent price performance for learning or the occasional job need Call for your custom product needs Free Quote Quick Response a e9 ARI HERAS p HiTech Equipment Corp 9400 Activity Road San Diego CA 92126 FAX 619 530 1458 619 566 1 892 eae 60 Issue 37 August 1993 The Compute Applica Listing 1 b Data is received 2t a low enough rate that BASIC can poll the joystick port and decode the incoming steam
141. ling SNS to ground For currents in the range of 3 9 amps an n channel power stage is usually employed as shown in Figure 5 Although requiring additional support components the n channel topology offers a price performance advantage at these higher current levels The n channel s gate must be driven positive with respect to the drain in this configuration in order to provide full enhancement of the power FET QI This is accomplished with the charge pump made up of C10 and CI 1 When the catch diode D10 is conducting CI 1 is charged When the n channel power FET is conducting C 11 charges C 10 providing adequate voltage to fully enhance the power driver QI via Q5 When Q2 conducts gate charge is depleted thereby turning Q1 off In all other respects this An Unbiased Survey for DOS Developers try with my software or Name Company Address City Phone j pianie aad b OG NO don t want to find out how Ican save a lot of money using ROM DOS 5 instead of MS DOS in our 80x86 product line don t care if ROM DOS 5 is compatible with MS DOS 5 but costs much less like spending much more than have to It makes me feel like a philanthropist and besides Microsoft probably needs the money more than do anyway J yes want to know the facts about ROM DOS 5 Please send me information and a free bootable demo disk to Inthe U S A Call Toll Free 1 800 221 6630 fax this coupon
142. lti Micro Systems 62 Bonaventura Dr San Jose CA 95 134 408 456 0333 Fax 408 456 0366 Passive backplane CPUs I O boards and packaging Octagon Systems 6510 W 91st Ave Westminster CO 80030 303 430 1500 Small form factor 4 5 x 5 PC compatible SBCs Paradigm Systems 3301 Country Club Rd 2214 Endwell NY 13760 607 748 5966 Fax 607 748 5968 Software adapts PC program ming tools to work with embedded PCs The BCC52 controller continues to be Micromint s best selling single board com puter Its cost effective architecture needs only a power supply and terminal to become a complete development system or single board solution in an end use system The BCC52 is programmable in BASIC 52 a fast full floating point interpreted BASIC or assembly language The BCC52 contains five RAM ROM sockets an intelligent 27641128 EPROM programmer three 8 bit parallel ports an auto baud rate detect serial console port a serial printer port and much more PROCESSOR 80C528 bit CMOS processor w BASIC 52 Three 16 bit counter timers Six interrupts Much morel Memory 48K RAM ROM expandable Five on board memory sockets Either 8K or 16K EPROM BCC52 BCC72C BCC7ll BCC32CX Controller board with BASIC 52 and 8K RAM Low power CMOS version of the BCC52 40 C to 85 C industrial temperature verston Low power CMOS expanded BCC52 w 32K RAM Input Output Consol
143. mputer Applications ournal Issue 37 August 1993 57 Figure 3 Anotner larger pnotosensor package EE 9Y148 uses a 74HU 14 for circuit hysteresis In addition focal between the transmitter and receiver is elongated The second sensor the 148 is a larger package This wedge shaped device has a focal length of 3 mm This time used a 74HCT14 to give the circuit a little hysteresis see Figure 3 for the circuit used with this device Mechanical support and alignment is easier with these devices because they have an elongated mounting hole between the transmit ter and receiver that makes focal length adjustments more manageable wired an output connector with the same configuration as with the previous circuit to allow the sensor circuits to be easily exchanged within the enclosure SIMPLE INTERFACE I ve used the PC s parallel port many times for interface projects However this time there is an advan tage to using a different port Since we re dealing with a device that provides input signals only the PC s joystick port has all the necessary signals needed to support this circuit It can provide power since it has 5 volts and ground normally used for the joystick s potentiometer and it has push button inputs that are pulled high internally with 1 k resistors and grounded by pushing a button Using BASIC the status of each push button can be polled to determine whether the attached sensor is seei
144. ms If you want improved design more efficient code more effective project management strategies and a look at the industry s big picture future call 415 905 23 54 now for details on the 93 Embedded Systems Conference 24 Issue 37 August1993 The Computer Applications J our nal can be realized with this circuit topology AC STABILITY ANALYSIS For Figure 6 modified the circuit Date Time run 01 01 80 00 48 47 Temperature 27 0 topology by reconnecting C 2 from Node 3 to ground and raising its value to 1 uF The results show that the circuit is now unconditionally stable TRAILING EDGE While the circuit shown in Figure 2 may not be the most useful op amp i j circuit ever created it has been useful nee Seer penn piece Picaigense eerie pint EE to explain some very powerful design 1 0h 10h 100h 1 0Kh 10Kh 100Kh 1 0Mh 10Mh techniques These techniques can be o DB VM 3 VM 5 used with any arbitrary circuit stabi POD a ne Fy aa pase ies a a Sat etete T E lized by negative feedback Just place the AC voltage source between the summing junction of the feedback and input network and the gain stage L Mark Nurczyk is a Registered Profes sional Engineer with 21 years experi ence in analog and digital design 7 1 1 FIRS ss 40h 10h 100h 1 0Kh 10Kh 100Kh 1 0Mh 10Mh a VP 3 VP 5 404 Very Useful FREQUENCY 405 Moderately Useful 406 Not Useful Figure 6 With C2 connected from node 3 to ground
145. n that voltage drops below 1 3 volts the Power Fail Output pin goes high The resistor divider and trimpot shown in Figure 4 set the trip point so that PFO is active before the RAM is disabled You can set the voltage without a trimpot but this lets you activate PFO and test the system without blipping the supply voltage Although you could wire PFO through an inverting driver to one of the system s interrupt lines if inter rupts are masked off when the power fails all is lost The solution is to use the IOCHCK IO Channel Check ISA bus line which activates the CPU s NMI Non Maskable Interrupt pin That interrupt cannot be ignored so the interrupt handler is sure to get attention Once the NMI handler is in control it can take whatever steps are needed to ensure a safe and orderly system shutdown With only a few milliseconds of power left however RESDRU BUS CONTROLS u24 REMOVE JUMPER TO DISABLE MAX6S1 POWER MONITOR INTERRUPT u19 LS245 FROM FRONT PANEL RESET PUSHBUTTON NORMALLY OPEN TIMEOUT AFTER RESET C 1 6 s 47pF WATCHDOG PERIOD C 400 ms 47pF HOWEVER THESE ARE VERY APPROXIMATE OSC SEL AND OSC IN HIGH BOARD RESET 7 CONNECTOR 1 6 SECOND TIMEOUT Amber R48 pis 3309 5320 P g u ON RESET ACTIVE Figure 4 The MAX691 monitors fhe power supply warns of impending power failure controls the backup battery and CE switching and includes a variable rate
146. n the ear of the user The speech processor is suitably of the type described in U S Pat No 4 441 202 Tong et al modified to cause stimulation of the digital nerves via the eight finger electrodes and a common electrode held in contact with the wrist of the user speech patterns via electrotactile stimulation of the fingers Since the mechanism for comprehending speech is thought SOURCE to be extremely complex and deeply embedded in the brain one wonders what sort of speech patterns can be recognized and utilized by the user of such a device Nevertheless it is an intriguing concept with many possible applications even short of full speech L Russ Reiss holds a Ph D in EE CS and has been active in Patent abstracts appearing in this column are from the Automated Patent Searching APS database from MicroPatent 25 Science Park New Haven CT 06511 203 786 5500 or 800 648 6787 electronics for over 25 years as industry consultant designer college professor entrepreneur and company president Using microprocessors since their inception he FIRS has incorporated them into scores of custom devices and new products He may be reached on the Circuit Cellar BBS or on CompuServe as 70054 1663 425 Very Useful 426 Moderately Useful 427 Not Useful The Computer Applications Journal Issue 37 August 1993 83 COMM ASTIME The Circuit Cellar BBS 300 1200 2400 9600 14 4k bps 24 hours 7 days a week 203 871 1988 Fo
147. nd the phase response was 147 1 0h 10h 100h 1 0Kh 10Kh 100Kh 1 0Mh 10Mh This phase margin of 33 may keep the o VP 3 VP 5 circuit stable but it is still shy of the FREQUENCY 45 defined as the minimum required Figure 5 is the best performance that Figure 5 Changing C2 to 1500 pF results jin a marginally stable circuit but is stil nof good enough The 1993 Embedded Systems Conference Speaks ALL Your Languages Hone the technical and management skills And you ll have direct access to dozens of today s top experts in you need for the entire embedded process cara SEA moane from writing code to executing a project at Real time modeling pioneers Paul Ward and Stephen Mellor the problem solving Embedded Systems Leading system development methodologist Derek Hatley Conf D E h d Microprocessor industry analyst Michael Slater onterence Dozens ot hands on program Structured design guru Larry Constantine ming and methodology workshops lectures im c expert PJ Plauger and tutorials cover topics such as And many more Design Methodology languages Chip Pius the largest exhibition of embedded development tools and Programming Digital Signal Processing e Fuzzy utilities so you can try the latest in logic analyzers in circuit emu logic e Debugging Networks e Hardware lators single board computers microprocessors microcontrollers Interfacing e Management debugging tools and real time operating syste
148. ng reflected light or not 58 Issue 37 August 1993 5 Top Track Bottom Track Ground Standard bar code techniques encode data as line width and or spacing widths This method is sensitive to constant scanning speed in order to accurately determine relative line space widths You may wish to experiment with this method but since have two tracks available can use a simpler approach No matter what approach you choose there is a need to determine where the actual data starts and in what sequence from what direction the data is being entered Therefore a start flag and an end flag should be possible data track 1 data track 0 Figure 4 Start and end codes mustbe used in any encoding Start 11410 data track TT clock track l l The Computer Applications Journal length adjustments false start data TINO EE EETA oP TAA Tie T EE 0 4 Joystick Port are easier because fhe mounting ho e used to frame the data sequence You can see the standard settled on for my setup in Figure 4 False sensing can occur when the card enters the sensor s detection zone So by using a minimum of three marks on one track followed by a space a start code is recognized False codes can occur prior to this without affecting the recognition of a true start If the opposite sequence is used as an end code the direction of the swipe can be established This can only safely be assumed if yo
149. ngineer that still lives and breathes in you Face it maybe the need for that kind of engineer is passing and itis time for a new kind of engineer to rise from the ashes like a phoenix Perhaps we are experiencing serendipity on a societal scale once heard that one of the biggest reasons for the lack of innovation was that we all got just a little too comfortable After all if necessity is the mother of invention who is going to be willing to bear the pain of labor if we are so complacently numbed that we don t perceive the need to do anything The proponents of this idea would say that while we slept those more desperate groups forged ahead because they did not suffer from our plight Where is that creative spark and ingenious curiosity that caused you to struggle to become an engineer The reason ask is we really need you now Never before have we needed innovators to take charge of the slumbering human spirit Never before have so many young persons needed some direction some inspiration to prevent their talents from being wasted as a hash slinger Never before was society in need of a grand reemergence of the entrepreneurial spirit And maybe just maybe you are the one to do it Hey every little bit helps Look around your community Is there a group of young persons that could be inspired to care about science and math If so take them under your wing by forming an electronics club Is there a school system that could u
150. ning op amps RC networks and assorted 74HCxx support logic Basic micro circuits are on a printed circuit board the memory and conditioning circuits are all point to point wired Board is enclosed in a plastic case All external wires are shielded drain wires connected to digital ground no chassis ground Separate battery from other electronics on car Micro is 6 feet from magneto 3 or 4 feet from closest spark plug wire The entire system works on the test bench It works in the pits with the engine running After initial teething problems were debugged all appears to function as de signed but the system will not work during a drag run On return to the PC based retrieval system in the pits the on board buffers are empty as if micro has restarted and or reinitialized During one test the I m alive blinking LED controlled from the RTI subsystem had stopped flashing SOO TIME only to restart later To eliminate the loose wire possibilities am starting to build a two sided circuit board It will have an extensive ground bus plane with filtering caps everywhere possible and a grounded aluminum enclosure If anyone out there has some suggestions would greatly appreciate them Msg 15187 From MICHAEL SWARTZENDRUBER To PAUL CONLIN How do you keep the parts from getting shook right out of their sockets Don t those railers rattle the brains of everyone everything sitting in them Msg 15218 From PAUL
151. nnected as shown The other control and data lines must be pulled active high The termination resistors he p to eliminate echoes on the bus a processor to automatically control the bus lines Take special note that used the 40 pin DIP version of Na tional Semiconductor s DP5380N Other packages may use different pinouts THE 5380 REGISTERS AND CONTROLS Three registers must be set in order to read from and write to the 5380 see Figure 4 the Output Data Register ODR the Initiator Com mand Register ICR and Mode Register 2 MR2 The registers are accessed by using address lines AO Al and A2 which are active high To access MR2 for example set AO and A3 low and pull Al high To access the ODR pull all three lines low The eight bits in each register are individu ally set using data lines DO D7 The 5380 is described in the Mass Storage Handbook published by National Semiconductor Those of you interested in doing further develop ment with the chip can find a com plete description of the device in that book SETTING THE 5380 REGISTERS First will present the general method of setting the 5380 registers then l Il give a specific example of how to set the registers to allow data to be written out to the SCSI bus To set a register first st CS high inactive Next set the address lines terminators identical to the above circuit appear on these lines to the binary address corresponding to t
152. ntation of a SCSI device we need some intelli gence provided by a processor or a PAL to control the 5380 CONNECTING THE MACINTOSH TO THE BREADBOARD Make sure the cable is carefully constructed since improperly con structed SCSI cables have been known to permanently disable a Mac motherboard In the creation of my project soldered short extensions onto the cable about 1 5 inches to allow the individual lines of ribbon cable to be easily inserted into the breadboard The cable construction is detailed in Figure 6 The plug used to connect to the SCSI port on the Macintosh is a male D dubminiature 25 pin connector The plug signal assignments are detailed in Figure 7 The sample driver code provided is written in 68000 assembly language and is used to place bits into the SCSI data registers Two separate code segments are provided one for reading and the other for writing to the data bus The code presented is designed purely for testing the interface and the breadboard so the first step is to reset and initialize the SCSI bus and then pause for the user to reset and initial ize the test breadboard The call to GetNextEvent simply waits for a mouse or keyboard event which allows time for the user to initialize the breadboard Next the MacsBug debugger is summoned to let the user single step through the code The PAL os ae F EPROM a EEPROM a FLASH MICRO prn 87C51 I PIC 93CC46 XC1 736 PSD 3x
153. o the input nodes 1 and 2 For bipolar op amps operating at high ambient temperatures current sources should be added from each input node to ground These current sources simu late the input bias currents of the op amp The bias currents can cause Listing l The amplifier in Figure 2 can be analyzed by writing a model for PSpice AC stability analysis 150 100U LMC660 1 10E6 SUBCKT LMC660 12 5 x RIN 1 vars kd Kiss GAIN AND PHASE CONTROL Gl 0 3 TABLE NPUT 3 0 100000 1136811 GAIN 3 0 UNITY GAIN 3 0 TABLE G2 GIVES 0 1 pS DELAY OUTPUT SECTI ON EOUT4 0 TABLE ROUT4 5 50 9 ENDS END vV 3 0 0 5 5 OUTPUT RESI STANC The Computer Applications Joumal oUTPUT 1 NVERTING NONI NVERTI NG MPEDANCE WELAI FEs 0 125402 0 el25025 NPUT NPUT SLEW RATE 1 1V 100K K FREQUENCY V 3 0 000001 0 125 1 4MHz 0 0 5 0 0 5 000001 0 125 5 VOLT POWER SUPPLY 50 9 OHMS Issue 37 August 1993 21 appreciable errors especially if the input and feedback resistors have high values G1 is a voltage controlled current source with a gain of 1 controlled by the voltage across R G1 in conjunc tion with R1 and Cl sets the voltage gain and frequency response of the op amp The value of R1 is set to be numerically equal to the open loop gain of the op amp The value of C1is determined by the unity gain cutoff frequency of the op amp
154. ola Dr Enola PA 17025 717 732 8800 Fax 717 732 8806 NEMA factory floor packaging for PCs and workstations Datalight 307 N Olympic 201 Arlington WA 98223 206 435 8086 Fax 206 435 0253 Software adapts PC program ming tools to work with embedded PCs Dover Electronics Mfg 1198 Boston Ave Longmont CO 80501 303 772 5933 Tiny 1 7 x 5 2 CPU and I O modules ERIM 602 962 5559 Fax 602 962 5750 PC 104 CPU board based on C amp T PC CHIP The Computer Applications Journal General Software P O Box 2571 Redmond WA 98073 206 391 4285 Fax 206 557 0736 DOS and BIOS tailored for use with enbedded PCs HM Systems Inc 2192 Dupont Dr 214 Irvine CA 927 15 714 955 2043 Fax 714 955 1849 386 and 486 passive backplane CPU boards Bus 9596 Chesapeake Dr San Diego CA 92123 800 382 4229 Fax 619 974 6494 Passive backplane CPUs and board packaging Industrial Computer Source P O Box 23058 San Diego CA 92 193 619 271 9340 Fax 619 271 9666 Passive backplane CPUs I O boards and packaging Innovative Integration 4086 Little Hollow Pl Moorpark CA 93021 805 529 7570 Fax 805 529 7932 TMS320 DSP based ISA bus coprocessor Issue 37 August 1993 67 68 Intecolor 2 150 Boggs Rd Duluth GA 30136 404 623 9145 Fax 404 623 9163 Passive backplane CPUs I O boards and packaging Integrated Systems Inc 32
155. on Typical accuracy ranges from 1 count to 2 counts All meters are overvolt age protected to 250 V with common mode voltage range of 2 0 V An optional HOLD RUN pin may be ordered if desired The display enable option allows the meter to be powered down when not in use The DMS 20PC starts at 29 each Datel Inc 11 Cabot Boulevard Mansfield MA 02048 508 339 3000 Fax 508 339 6356 TIE prepn oot o peep m C ak 9 z DO YOU NEED CONTROL Ciarcia If yov re looking for a temperature sensor that allows your computer to not only monitor the ID e S 1 g n temperature but respond to it look no further V 7 Temp A Chipm is a solid state temperature Or k S sensor providing truly linear measurement of temperature The Temp A Chipm is an intelligent user configurable sensor which interfaces with your computer No batteries are needed to operate the Temp A Chipm it plugs into any standard RS232 interface Does your big company marketing Steve Ciarcia and the Ciarcia Design Works staff may have the solution department come up with more ideas We have a team of accomplished programmers and engineers ready to than the engineering department can design products or solve tricky engineering problems Whether you T A Chi emp A Chip cope with Are you a small company E LCD Display B Solid State Design need an on line solution for a unique problem a product for a startup 9
156. on with any input device being used TRANSFORMS AND PROJ ECT VERTICES When objects for a virtual world are described they are put into world The Computer Applications our nal coordinates World coordinates are based on a three dimensional coordi nate system The projection of the coordinates of an object s vertices onto the computer screen coordinates requires several steps The first step in the projection of coordinate points between different coordinate systems is to convert the vertices from world coordinates to view space coordinates The most common system for the view space is the perspective coordinate system Figure 3 shows what a perspective view does to a cube drawn on the screen and the values used to create it The perspective view is used to create the illusion of depth in the screen image The following formulas convert world coordinates to perspec tive view coordinates Vx Vy SCREEN_WIDTH 2 SCREEN_HEIGHT 2 KZ y z Notice that the z coordinate stays the same from world to view coordi nates The last step in the projection is to convert the view coordinates to screen space coordinates These coordinates are the actual x y position of pixels on the screen that will make up the objects Since there is no z coordinate for computer screens it is simply discarded In addition to the projection of the object vertices the computer program must move objects in accordance with the user s inte
157. onnects to the EPROM 40 ns emulation socket of the system The PROMJet sells under development and for 295 in a 2M the printer port of a PC 256Kx8 85 ns version After downloading the A 4M 5 12K x 8 sells for data from the PC the 495 and an 8M 1Mx8 PROMJet resets the sells for 695 target system and emulates its EPROM WesTec Research The PROMJet is software Corporation configurable no jumpers 2750 Riverside Dr Ste 205 and operates in both Los Angeles CA 90039 DOS and Windows 213 664 8909 environments Multiple PROMJets 503 The Computer Applications Journal Issue 37 August 1993 7 INT ALD lt 0 d eine NEWS CEBUS PROTOCOL ANALYZER CEBugger a CEBus protocol analyzer from Command Control Inc provides the developer with an easy way to observe and analyze a CEBus network It allows the capture display and analysis of CEBus packets CEBugger may be set to filter the packets or trigger a capture on a specific packet or event CEBugger will check for errors and protocol violations The CEBugger package consists of a 16 bit IBM AT bus card a CEBus modem and software that runs on the PC A 16 MHz 80C196KC microcontroller on the card executes the CEBus Data Link Layer DLL software This software is loaded onto the card through the PC s DMA channel at runtime so the same card may be used with CEBugger CEBnode or other programs without changing EPROMs E
158. ons to The Computer Applications J ournal Subscriptions P O Box 7694 Riverton NJ 08077 or call 609 786 0409 POSTMASTER Please send address changes to The Computer Applications J ournal Circulation Dept P 0 Box 7694 Riverton Nj 08077 ART DIRECTOR Lisa Ferry GRAPHIC ARTIST Joseph Quinlan CONTRIBUTORS Jon Elson Tim McDonough Frank Kuechmann Pellervo Kaskinen Cover Illustration by Bob Schuchman PRINTED IN THE UNITED STATES HAJAR ASSOCIATES NATIONAL ADVERTISING REPRESENTATIVES NORTHEAST Debra Andersen 617 769 8950 Fax 617 769 8982 MID ATLANTIC Barbara Best 908 741 7744 Fax 908 741 6823 SOUTHEAST Christa Collins 305 966 3939 Fax 305 985 8457 MIDWEST Nanette Traetow 708 789 3080 Fax 708 789 3082 WEST COAST Barbara J ones amp Shelley Rainey 714 540 3554 Fax 714 540 7103 Circuit Cellar BBS 24Hrs 300 1200 2400 9600 14 4k bps 8 bits no parity 1 stop bit 203 871 1988 2400 9600 bps Courier HST 203 871 0549 All programs and schematicsin Circuit Cellar INK have been carefully reviewed to ensure their performance isinaccordance with the specifications described and programs are posted on the Circuit Cellar BBS for electronic transfer by subscribers Circuit Cellar INK makes no warranties and assumes no responsibility orliability of any kind for errorsin these programs or schematics or for the consequences of any such errors Furthermore because of possible va
159. ontinuous Charae Pulse charge CC Active r the im ka eas gt je CC Active z Burp Charge lt a CC Active CD Active Trickle Charge gt l cc Active Interval 1 4 Interval 2 Begin Charge Interval N Termination Figure 6 There are more ways to charge a battery than simply applying a constant voltage or current to if A dedi ated battery management IC can handle ali manner of charging methods Which you choose depends on your battery and a amp cation Obviously it is intended for high end computer products that can tolerate the significant engineering effort required to put it on the air this isn t the kind of thing you re going to get fired up in your basement some spare evening However you could get your feet wet gradually by putting it on line a piece at a time This would be a good idea with such a complex peripheral For example if you needed a multistage burp charger it wouldn t be too difficult to program the rdevant EEPROM register to obtain this functionality While many ICs come with evaluation boards that you can use to test drive the circuits the bq2001 features a full blown development system The development system is centered around an 80C32 controller with an on board 10 bit A D converter for battery characterization 32K of nonvolatile RAM for storing historical battery data an RS 232 interface a bunch of indicator LEDs and
160. ontrol and the system boots normally The RAM is enabled when the MAX691 releases the reset line so the RAM will be ready for the first firmware access Figure 4 shows connections to both RstDrv and the system board Reset connector The two are not identical Reset is normally wired to the front panel Reset switch while RstDrv is an ISA bus output You cannot drive RstDrv and you do not have direct access to the signal that actually resets the CPU kludged a small adapter from jumpers and header pins for the Reset connection the front panel switch plugs into the adapter which then plugs into the system board A two conductor wire joins the adapter to a header on the Firmware Devdopment board If you connect the thing backwards the FDB s ground will hold system reset low but that goof is easy to find 52 Issue 37 August 1993 Listing P This routine decides if a Non M amp able Interrupt was caused by the MAX691 s Power Fail defector If so if write profecfs the RAM lights a decimal point and enters a spin loop waiting for Reset if not if passes control to the NMI handler set up by the BIOS HandlerNMI asm PUSH AX PUSH DX PUSH DS OV AX CS OV DS AX Check to see if N AX DX Punt TEST NZ MI_Chain We have a power failure OUT DX AX Punt V V AX 0080 T DX AX n t NMI_Lock P lt NMI_Lock Chain to previous NMI handler NMI Chain POP DS POP
161. ownload files the software is also available on one 360K IBM PC format disk for only 12 To order Software on Disk send check or money order to The Computer Applications Journal Software On Disk P O Box 772 Vernon CT 06066 or use your VISA or Mastercard and call 203 875 2199 Be sure to specify the issue number of each disk you order Please add 3 for shipping outside the U S 428 Very Useful 429 Moderately Useful 430 Not Useful SEATON INK Engineer Design Thyself f the physician is admonished to heal himself perhaps the engineer s equivalent would be to design himself During this period when downsizing to regain margins is dangerously popular many senior or mid level engineers are being asked to find something else to do and someone else to do it for While would be the last person to minimize the plight of my brethren who suddenly find themselves in this challenging condition will not hesitate to admonish you to design yourselves Apply yourself to discovering a solution That s what your professors hoped you would get out of all of the incredibly challenging assignments How many of us accepted the siren call of those tempting us with the keys to the palace and were transformed into paper pushing report writing mostly managing desk pilots Don t get me wrong I m sure these tasks serve some useful purpose but any bean counter can do that kind of thing So let them do it Recharge the e
162. p A Chip software package can be modified to meet specific needs The Temp A Chip is fully powered from a 9600 bps standard serial port XT or AT connector available and is useful over a temperature range of O 15 F 1746 C It features an LCD screen with constant temperature readout The unit is programmable from Windows or DOS and may be controlled from any communications package The Temp A Chip sells for 99 95 plus shipping and handling A 30 day money back guarantee is provided Parham P Baker amp Associates Inc 153 Burt Rd Lexington KY 40503 606 278 8699 Fax 606 277 7514 Issue 37 August 1993 The Computer Applications Journal LOW COST ANALOG I O MODULE A complete 12 bit analog input output module for PC 104 compatible embedded systems has been intro duced by WinSystems The PCM AIO provides afford able high speed data acquisition and control functions with conversion speeds of 10 microseconds per channel The heart of the board is the Maxim MAX180 12 bit data acquisition chip This device combines an 8 channel input multiplexer high bandwidth track and hold a low drift zener reference high speed successive approximation analog to digital converter ADC and flexible microprocessor interface on a single chip It supports up to eight single ended or four differential analog inputs which are software selectable on a per channel basis The MAX180 samples and digitizes at a 100 kHz throughput r
163. photodiode GP1US52Y 40 kHz JR receiver side looking ULN3751Z Power op amp 3V to 13V supply 3 5 A output 1S1U60 38 kHz IR receiver UDN2993B Duat full H bridge bipolar stepper motor driver IRSAMPLE parts PH302 LM311 etc See MCIR Link article INK 29 Excellent IR filter opaque to visible light 35 mm slide mount MC145030 IR encoder decoder D 1232 Micromonitor watchdog UCNS5841A Serial input 8 latched 500 mA sink drivers UCN5895A Serial input 8 latched 250 mA source drivers UCN5804B Unipolar stepper motor translator driver CS212 S ART 1 0 network security monitor DS2400 Silicon Serial Number 2 chips DS1210 NVRAM power conroller DS1231 Power monitor IR VO 1S1U60 LD273 CD4047 2N2907 red LED schematic 1F Link MAX691 Power supervisor DS1202 Serial clock calendar 757204 DTMF decoder IL300 finear optoisolator MAX233 seif contained 5V powered RS 232 interface MT8880 DTMF encoder decoder bus interface PL513 Send only X10 power fine interface MAX134 digital multimeter MAX252 optically isolated 5V powered RS 232 interface Call write fax for sertously tempting catalog Pure Unobtainium P gt Your unusual part5 source 4 13109 0l d Creedmoor Road Raleigh NC 27613 FAX voice 919 676 4525 0 0 0 0 300 0 0 0 0 NULL gt Project Parts lt Firmware Flyers prices shown are postpaid in US with any parts order 18 15 10 8 3 2 3 2 45 70 2 10 2 25 2 30 2 85 3 10 4 00
164. pport e 30 day money back guarantee Help Is Available Call today for complete product information and embedded system application solutions You won t be disappointed PARADIGM Proven Solutions for Embedded C C Developers Paradigm Systems 3301 Country Club Road Suite 2214 Endwell NY 13760 TEL 607 748 5966 FAX 607 748 5968 Trademarks are property of respective holders The Computer Applications Journal Issue 37 August 1993 9 SUBMINIATURE DIGITAL VOLTMETER A fully functional 3 digit precision digital voltmeter occupying just over a half cubic inch total volume has been announced by Datel Inc These self contained plug in modules provide research grade accuracy reliability and low cost in a component size DDIP package The DMS 20PC is available in signal input configurations ranging from 0 2 V to 200 V The display can be in several colors including high density red and low power red less than 7 mA power drain The units feature a large 0 37 LED display have an integrated bezel and are fully encapsulated to withstand harsh environments All models feature high impedance typically 1000 MQ differential inputs autozero display and autopolarity indication while employing an ultrastable reference circuit Decimal point placement is user selectable Long term stability is achieved through an advanced autozeroing ADC which never requires adjustment or calibrati
165. put Current with DACK with DACK Data Register SCSI Data Data Register SCSI Data with DACK Output Data Register Initiator Command Register Mode Register 2 Target Command Register Select Enable Register Start DMA Send Start DMA Target Start DMA Intiator Current SCSI Data Initiator Command Register Mode Register 2 Target Command Register Current SCSI Bus Status Bus and Status Resgister Input Data Register Reset Parity Interrup Receive Receive lnvoke Macsbug debugger D2 D7 A2 A4 A7 SCSIBase SCSIGlobals SCSI Data the address of the read straight AO contains the data can be s up to the peripheral to place sections of the SCSI protocol ine when the data is available ion through the first mouse presented in the article to set o imitate a peripheral placing can also choose to set the bus avoiding the 5380 chip the continued The Computer Applications our nal step debugger n GetNextEvent mDownMask keyDownMask amp event Wj wi thDACK if S 7 a KT A ts lt i xy x in Progress Click mouse to continue n n installed n n The code in Listing 2 contains a routine for reading that is much simpler than the write routine CONCLUSIONS The code presented in this article demonstrates how to access the 5380 SCSI driver chip This access shoul
166. r FREEDEMODI SK Call today to ask about FREE 8051 Macro Assembler 800 METAICE 800 638 2423 Metik Corporation PO Box 1329 Chonde tr 85244 1329 Phone 602 9260797 FAX 602 9261198 TELEX 4998050MTNK IceMASTER Improved User Interface Features m iceMASTER is convenient t connects easily to your PC requires no disassembly nor does it take up any expansion slots It works on any PC DOS or 05 2 Micro Channelor EISA Even Laptops m Supports source level debug C and PL M and source level trace 4K trace buffer with odvonced searching and filter ing capabilities E Now virtual memory W and mouse support ance 7 7 Corporation 109 The Computer Applications Journal Issue 37 August 19 93 17 typedef struct_viewpoint Xform view matrix TAngle pan tilt roll 3 Fixedpoint stereo d Stereo e VIEWPOINT Figure 8 The VIEWPOINT structure contains alfthe information about the location of the user relative to the scene being observed parameter and returns the root object after reading the joint file successfully The word root is followed by a virtual word for the root object Instead of using obscure filenames for the name of objects in the joint file virtual words are used For this example I will used in the joint file will use two cubes and place them in different locations of the screen The first cube is defined as
167. r Less Than The Cutting Edge _ HIGH PERFORMANCE Guaranteed 16 pit accuracy 6 Channel A D e 16 bit ND penne e 16 bit accura cy 50 kHz throughput eDMA 8 lines di ital VO e 3 channel counter timer LOW COST 16 bit 8 16 Channel A D Board e16 it A D resolution e 15 kHz throughput e DMA e5 lines di ital I O 3 channe a niecliner OPTIMUM CONVERSION DT2801 57 5716 compatible 16 i AD resolution 16 bit accuracy DMA Pro q Gain 16 lines dlaital VO 3 channel counter timer e 2 D A channels 1295 895 1395 Cut through the specs each of ADAC s 16 bit boards have been evaluated against every competing model On noise performance speed ease of use and price ADAC s leading technology wins every time See for yourself Call for an evaluation board today 1 800 648 6589 We ve been making data acquisition boards for longer than anyone in the world poration 70 Tower Office Park Woburn MA01801 FAX 617 938 6553 TEL 617 935 6668 Analog amp Digital 1 0 Industrial PCs and High Channel Count Systems 130 Issue 37 August 1993 53 after 16 more bits the interrupt handler enters the tight loop at W D_ Lock Because the watchdog output bit no longer toggles the MAX691 will eventually reset the system The mainline code thus has two responsibilities it must load a bit pattern into Watch B i t S at least once and it must clear Watch F 1 ag
168. ractions with the input device If the user wants a specific object moved some distance in the x coordinate direction the computer program must recalculate each vertice s coordinate to adjust the vertices of the object accordingly This adjustment is usually performed using transformation matrices Below is an example of a transformation matrix for object translation movement 1000 0100 0010 ty ti All vertices of an object have to be transformed using matrix multiplica tion These calculations are obviously Issue 37 August 1993 13 SONNNNOO CL SMUNDONNOD Figure 3 The first step in the projection of coordinate points between different coordinate systems is to convert the vertices from world coordinates to view space coordinates very compute intensive because of the number of pixels involved especially when considering that the renderer must work in real time SORT OBJ ECTS ON Z DEPTH Once all of the objects have been given view and screen coordinates we sort the objects based on their z coordinate The purpose of sorting is to determine which objects are in front of other objects If we have two objects A and B and object A is in front of object B the program will have to draw object B first and then object A to give the illusion of spatial or depth relationships between objects in the virtual world The result of this is shown in Figure 4a If the program were to draw A an
169. rcuit R Msuppry X Rroap Your Rroan OUT Temperature 27 0 G2 prevents the voltage on node 3 from raising too high When the voltage limit is reached G2 generates a current with the opposite magni tude of G1G2 s current prevents any further voltage drop across R 1 Selecting the turn on voltage of G2 to be greater than the limiting voltage of Eoyr will model the propagation delay of the op amp Choosing node 3 s limiting voltage to be 1 volt larger than Eour s 7 will produce a dday of 1 us if the slew rate of the op amp is 1 V us Vout Everybody s using DSP How do we get started IT SFINALY HERE ACOMPLETE DSP DEVELOPMENT SOLU TION BASED ON THE POWERFUL AND EASY TO PROGRAM amp ADSP 2111 DSP CONTROL RESOURCES PC 21 11 NOW MAKES IT EASIER THAT EVER TO BRING SPEECH TO YOUR PRODUCTS cam COMPLETE HARDWARE The PC 21 11 contains a 12 MHz 2111 DSP 8K Program RAM 8K Data RAM Microphone and Speaker Amplifiers and Ma ar Port It can also be used outside the PC with only a 5V power supply COMPLETE SOFTWARE Included software allows you to download your DSP programs and record and playback speech An application framework and running speech recognition and speech compression code are also Included The ADSP 2111 Assembler Linker Simulator can optionally be purchaced with A the card A COMPLETE SOLUTION In short the PC 21 11 gives you s everything you need to get an immediate
170. rder both volumes and save regularly 17 95 each VISA Mastercard or International Postal Money Order U S funds drawn on U S bank only Circuit Cellar Project File 4 Park Street Vernon CT 06066 Canada Mexico via U S addresses via U S Mail Tel 203 875 2199 Fax 203 872 2204 includes domestic elven Please add 6 per copy for delivery 2 Ma U il add 8 per copy for other non 132 The Computer Applications Joumal CS gees A DIMSION OF MING Engineering amp Products inc 800 669 4406 RF Trans amp Recv Set The RC 99 RF Transmitter amp Receiver Set 300MHz 12 bit address or 8 address amp 4 data Ed Nisley as Nisley Micro Engineer ing makes small computers do amazing things He s also a member of the Computer Applications Journal s engineering staff You may reach him on CompuServe at 74065 1363 or through the Circuit Cellar BBS SOURCE Pure Unobtainium has the MAX691 and selected parts for the Embedded 386SX series as well as the schematics for everything to date Write for a catalog Pure Unobtainium 13 109 Old Creedmoor Rd Raleigh NC 27613 Voice Fax 9 19 676 4525 413 Very Useful 414 Moderately Useful 415 Not Useful 17921 Rowland Street City of Industry CA 91748 Technical Support 818 912 9864 AMERICAN EXPRESS 3 42 FREE UPS when you buy two or more UPS Ground on purchases over 50
171. re fault levels Second the voltage of the cell must be between the end of discharge voltage and the maximum cell voltage If a discharge before charge cycle is selected it is performed prior to initiation of fast charging Once fast charging begins delta temperature delta time and or negative delta voltage are monitored to determine when a full charge has been reached Temperature cutoff maximum voltage and maximum time are tested in order to stop the fast charge if for any reason the primary cutoff mecha nisms should fail This redundant testing method is used for fail safe operation Of course under normal conditions the primary fast charge cutoff mechanism should work just fine but the experienced engineer understands the need for backup schemes This understanding often overcomes the uninitiated right about the time they move their designs from the sterile confines of the workbench into the cold cruel world Frequently this experience is amplified when the single prototype suddenly spawns a bunch of production units that find their way into less than friendly environments In any event realize that the primary charge determination signals operate at relatively low level voltages It would be a shame if a glitch or some other system anomaly caused costly batteries to dry up or outgas These backup schemes exist for a reason With a general understanding of the bq2003 s pin functions and charging strategy r
172. re golden Drivers signal is activated whenever OV OX LED_ADDR_A nonzero says we have trouble OV AX 8000 left decimal point flags problem the system board sees a hardware OUT DX AX reset In principle this line should be activated whenever the Power Good WD_Lock MP lt WD Lock stay here until watchdog timeout signal is low so that all of the PC s l Seid hile th WD_Load MOV AX WatchBits fetch new bits Arot yesir ESEE WA E NE Poe te OV WatchShift AX for the shift reg out of tolerance OV gt WatchCounter 16 reload the counter However to quote Solari The NC gt WatcnPending set flag for mainline code above information is a combination of the IEEE P996 specification and Blip the watchdog output to ensure a transition every time various IBM technical reference WD Go MOV DX CTLS_ADDR_A set up for watchdog output manuals It is sometimes unclear MOV AX Ctl sCopy get existing bits which platforms adhere to these i D i RERS Gah SENT a kow CEDON specifications Punt I ve seen supplies without a Power OR AX WATCHDOG_A d a high LED OFF Good signal evidently depending on OUT DX AX the system board s nonexistent reset Bai fi In f ked e watchdog bits and send the high one circuitry n act one group wor e bit so 1 turns the LED ON like it should with simply tied the system board s Power Good line to a capacitor and gt WatchShift get high order bit in C ignored the
173. removes bias from Q3 This enables the constant current source which is based on the ubiqui tous LM 317 U2 Using the formula T 1 25V R16 the current can be set up to a maximum of 1 5 A In this type of Single cell battery voltage input A voltage level developed by a high impedance resistor divider between the positive and negative battery terminals that sets the single cell voltage for the battery being used Maximum cell voltage threshold input The voltage at this pin sets the maximum single cell voltage Temperature sense input Connection to an external battery temperature monitoring negative tempera ture coefficient NTC thermistor Temperature cutoff threshold input The voltage at this pin sets the maximum allowable battery temperature Charge initiation and discharge before charge control inputs When both CCMD and DCMD are at VCC or when both are connected to VSS charge initiation is automatically started on battery replacement or application of VCC Charge is also initiated by a rising edge to VCC at CCMD if both CCMD and DCMD are connected to VSS or by a falling edged on CCMD if both CCMD and DCMD are connected to VCC Discharge before charge is initiated by a rising edge at DCMD if both DCMD and CCMD are connected to VSS or by a negative going edge on DCMD if both DCMD and CCMD are connected to VCC Negative delta voltage enable input If this input is high negative delta voltage charge termination is enabled D
174. riation in thequality and condition ofmaterials and workmanship of reader assembled projects Circuit Cellar INK disclaims any responsiblity for the safe and proper function of reader assembled projects based upon or from plans descriptions or information published in Circuit Cellar INK Entire contents copyright 1993 by Circuit Cellar Incorporated All rights reserved Reproduction of this publicationin whole orinpart without written consent from Circuit Cellar Inc is prohibited An Introduction to PC based Virtual Reality by Joseph D Gradecki Oscillators Don t Amplifiers Do by Mark Nurczyk P E Real world Macintosh A Mac SCSI interface primer by Marc Bumble A Parallel Expander for the PC by John F Lenihan LL Firmware Furnace 44 Absolute Power Corrupts The 386SX Project Gets a Watchdog Ed Nisley LL From the Bench 5 6 Take a Swipe at Optical ID Cards Jeff Bachiochi U Silicon Update 6 2 In Bed With PCs Tom Can trdl L Embedded Techniques Support Your Batteries John Dybowski ConnecTime 84 Excerpts from the Circuit Cellar BBS conducted by Ken Davidson Editor s INK Ken Davidson Pavlov Would Be Proud New Product News edited by Harv Weiner Patent Talk Russ Reiss Steve s Own INK Steve Ciarcia Engineer Design Thyself Advertiser s Index 81 The Computer Applications ournal Issue 37 August 1993 3
175. s initial state the next step is to configure the chip to place data on the SCSI bus using MR2 ICR and ODR see Figure 4 The first step in setting the 5380 registers is to set ICR bit 3 BSY ICR is located at offset 1 and is shown in detail in Figure 5a After the ICR BSY line is set bit 6 of MR2 offset 2 is enabled All other bits in MR2 are disabled The address control and data pins must be set as shown in Figure 5b Once the pins are set up click the CS pin momentarily over to the 0 state to enable the data in MR2 After MR2 is set the ICR settings can be configured The DBUS bit must be set to enable the contents of ODR onto the SCSI bus data lines The parity bit DBP will also be automatically generated by this operation To set this register configure the DIP switches as shown in Figure 5c Once again momentarily switch CS to 0 in order to write the data to the register To set data onto the bus simply write data to the ODR The pin settings for this operation are shown in Figure 5d When CS is set to 0 the data indicated by the DBO DB7 lines will be flushed out onto the bus You can leave CS se to 0 and use the DBO DB7 lines to change the data on the bus Of course this presentation is not the standard manipulation of the SCSI control lines and protocol but instead it serves to illustrate the basic opera tions of a SCSI communications device For a full impleme
176. s not only connect objects but allow the developer to limit the movement of each of the objects based on the movement of jointed objects Thus if the palm of the hand moves to the left in the world the finger will follow because they are jointed If any of the finger segments is rotated the jointed object rotates as well If a limit is placed on the rotation of one of the objects it will not rotate beyond this limit even if a jointed segment is rotated further Limits can also be imposed on the placement in the world such as limiting the forward motion of the object To illustrate the format of a J OINTS file we will look at placing two cube objects in a world and creating a joint between them should note that objects do not have to be touching to be jointed All OINTS files have a root object A pointer to this object is returned when ther e a d_j oi nt function is called The read_joint function accepts a filename string as a 8051 6BHCII COPB 68HC05 Rental And 1 0 Day Trials Available mw iceMASTER delivers productivity easy to learn easy to use and fast wy Wperlinked On line help guides you through the emilotion process mM iceMASTER is FAST The 15 2K baud serial link keeps typical dow nload times to under 3 seconds using a standard COMM port HM Broad support of derivative devices M Flexible user interface you ton completely config ure the windows for size content location and color Calltoday fo
177. se some expertise in their computer science or voc tech programs Share the wealth of your experience with them the next generation will benefit from your concern Is there anything you ever thought would be a neat product or some service you could perform Now is the time to do it You may never have this kind of opportunity again So guess what I m saying is to ignore the doomsayers Now is one of the most challenging times in human history There are a multitude of problems out there that need skilled persons like you Remember that of all the most remarkable discoveries made by humanity most were made by individuals not huge conglomerations Don t hesitate to be a lone reed in the wind Engineer design thyself and let the world benefit from having known you Sie 96 Issue 37 August 1993 The Computer Applications Journal
178. sor modes built into microcontroller serial ports Our flexible software and hardware allow developers to create powerful yet inexpensive master slave multidrop embedded controller networks Up to 250 nodes 16 bit CRC error checking with sequence numbers Low network overhead and low resource requirements RS 485 interface card for the PC Complete source code included Comprehensive documentation IMETRICS ECHNOLOGY 120 West State Street Ithaca NY 14850 TEL 607 273 5715 FAX 607 273 5712 131 lt _ _ _ _ 5 5 ft Max Length Solid 20 Ga Copper Wire vies Stranded Ribbon Cable Insulation on 20 Ga Wire So Ider Shrink Tubing Beamer Insulation on Ribbon Cable Figure 6 Proper construction of the connection cable wilf he p lead to successful experimental results Twenty gauge wire allows for easy insertion into the breadboard Listing Using a mix of C and assembler the write test code simply sends out an alternating bit pattern on the SCSI bus clude lt stdio h gt include lt sane h gt OSErr result fine SCSIBase ine SCSIGlobals ine dackWr fine ine ine efine tdefine define define define define define define define i define e e e e e e e e e DMAtx sTDMArx s IDMArx sCDR sRdICR SRdMR2 SRdTCR sCSR sBSR sIDR SRESET defin def
179. st ISA boards and chipsets Finally the Radisys EMC pack ages the PC in a true industrial strength package with extended temperature shock and vibration specifications Photo 4c In fact the EMC even complies with military specifications for rugged instruments The only caveat with the propri etary route is that everything is sole sourced However be reassured by the fact that suppliers realize they have to offer a complete selection of add ons at a competitive price ALMOST PCs Besides price and hardware expandability there is a class of embedded designs that exploits the final advantage of PCs great develop ment tools These PC pretenders trade off strict compatibility in favor of low cost small size low power and industrial type I O Unlike the other approaches you shouldn t even try to configure a true PC with this technol ogy which needless to say fails the Flight Simulator test Rather boards like the Micromint RTC V25 and R L C Enterprises Mini C186 are only designed with enough compatibility to allow the use of popular PC based tools such as Borland C The embedded and desktop PCs are linked with a serial port and pack ages such as those from Paradigm Datalight and others that enable source levea debugging of code execut ing on the target The RTC V25 Photo 5a combines the NEC 8088 like V25 CPU with 32 parallel I O lines an S channe ADC 8 or lo bit battery backed clock calendar
180. supportive of the lifelong work of T T Brown who also showed that mass in relation to space could be affected by electric potentials Next refer to The Possibility of the Experimental Study of the Properties of Time by N Kozyrev JPRS 45238 2 May 1968 the document is available from the National Technical Information Service NTIS an agency of the U S Department of Commerce 5285 Port Royal Rd Springfield VA 22161 703 487 4650 for 9 95 3 shipping Some have said that what Kozyrev was calling time actually was aether by another time His experiments showed anomalies in time And a odd drift of about 420 km s which leads us to the next stage the Silvertooth experiment Concerning the Silvertooth experiment The Michel son M orley experiment which did not show any transla tional motion through an aether or other medium of propagation was later shown to have a fundamental flaw The standing waves that are reflected back onto a mirror become phase locked on the mirror and hence to its motion through space Silvertooth built a standing wave experi ment that avoids the phase locking encountered in the Michelson Morley setup It uses a configuration similar to the Sagnac experiment which many years ago did detect motion relative to an aether Silvertooth s addition was a sensor capable of measuring the spacing between standing wave nodes This spacing is dependent upon the orientation of the apparatus rdiative to t
181. t the allowable reverse charging current to a reasonable value The MAX691 limits charging current to 10 nA typical 100 nA maximum and IpA over the full temperature range This may not be good enough for a UL rating particu larly for extended temperature applica tions So you may need a series diode anyway decided to skip the issue as the Firmware Development Board is not intended to be UL rated The UL requirements specify a current limiting resistor in case the diode is damaged The fault current is 5mA regardless of battery capacity The resistor value is the maximum possible supply voltage minus the cell voltage divided by 5 mA which works out as follows 5 5 3 volts T 500 ohms The next higher standard value is 560 ohms included this resistor to prevent problems should the MAX691 succumb to a static zap but l Il admit this isn t consistent The MA X69 1 requires a bypass capacitor on pin 2 to stabilize the internal voltage comparator and switch It s also essential because the chip can supply only 50 mA of current even when powered from the normal supply If your circuitry requires more than that the data sheet shows how to boost the current without affecting the backup battery Listing Producing a regular heartbeat on the wafchdog pin requires an interrupt handler attached foa timer tick This code rotates a 16 bit variable and sends the high order bit fo the watchdog To avoid sending
182. ta byte on to the SCSI bus Figure 5 A basic write to the SCS bus through fhe 5380 includes a setting the Initiator Command Register ICR in prepartion for setting MR2 b setting the Mode Regsiter 2 MR2 c setting the ICR again to enable data onfo the bus and d setting the actual data in the Output Data Register ODR 8051 EMBEDDED CONTROLLERS With Lots of Extras We offer a full line of low cost 80C32 embedded controllers and software tools which are ideal for developing products test fixtures and prototypes Features Include Low power CMOS design Up to 60K of code space and up to 60K of data space 5 to 15 volt operation e Small form factor 3 5 6 5 with prototyping area System diskette includes application notes e Start at 100 Available Options e Multifunction Board adds A D 24 I O lines and more BASIC 52 or Monitor Debugger in EPROM eC Compiler 100 or BASIC Compiler for 300 lota Systems Inc POB 8987 Incline Village NV 89452 PH 702 831 6302 FAX 702 831 4629 116 30 Issue 37 August 1993 The Computer Applications Journal O Solution is the U Answer to your COR Embedded PC XT AT 8051 Mg 80C186EB EC 68HC11 68HC16 e Cimetrics Technology O Th Ci tics Technol 9 Bit Solution is a complete microcontroller network ey that supports the 8051 HC11 80186 and many other popular processors The 9 Bit Solution takes full advantage of multiproces
183. tch the pricing of a PC itself On the other hand appearances to the contrary a rugged package does not a rugged PC make Make sure your setup can meet the hermetic tempera ture and vibration specs demanded by your application Also a desktop PC doesn t lend itself to easy maintenance as anyone who has had to do a motherboard swap knows PASSIVE BACKPLANE PCs For a more robust but still com pletely hardware and software compat ible alternative consider a passive backplane PC As the name implies this scheme adopts the traditional card cage approach in which all the PC motherboard logic is scooped onto a PC bus whether it s AT ISA or even EISA or MCA plug in board Com pared to a desktop PC a motherboard swap for purposes of maintenance or upgrade becomes a 60 second rather than 60 minute proposition Photo 2e When space is an issue the Advantech MBPC 640 with ifs three half size slots is sufficient for many applications Issue 37 August 1993 63 One of the advantages of the passive backplane approach is a wide range of size and expandability options For example consider the range of offerings from Advantech The IPC 616 packs a 16 slot motherboard and a hefty 250 W power supply into a 19 rack mount chassis Photo 2a A correspondingly beefy CPU is the PCA 6146 Photo 2b which matches the specs of top end desktop computers 486DxX up to 16M of DRAM 256K of cache
184. te when the atoms are flipping is exactly 9 192 631 770 per second Conveniently the frequency needed to make them flip is 9 19263 1770 GHz and the count of the flipping atoms is fed back as a frequency standard to keep the field on frequency phase locked loop PLL According to Dr Winkler of the Naval Observatory the idea of an atomic clock was first suggested 40 years ago in a lecture by Professor A Rabi of Columbia University The oscillation of the cesium atom was first observed in 1952 by Harold Lyons of NBS according to Beehler The first atomic standard in full time operation was at Britain s National Physical Laboratory in 1955 Now for the fun anomalies If remember my conventional physics correctly the charge of an object should not affect its mass or its moment of inertia time But we have from An Electrically Charged Torque Pendulum by Dr Erwin J Saxl Pin Hill Harvard Mass Nature vol 203 pp 136 138 7 11 64 Unexpected phenomena were noted as follows 1 When the pendulum was charged electrically with different carefully controlled electrostatic voltages together with its equipotential shields it was observed that positive and negative charges caused different delays A positive charge caused the pendulum to rotate slower as a rule than when the pendulum was charged negatively The grounded pendulum swung fastest there are exceptions to this rule at times This is
185. terrupt can be caused by a system board parity check or fhe ISA bus IOCHCK signal Your firmware can determine which input is active and mask if off by using these bits in 1 O port 0x61 Some systems have additional NM sources with differenf controls Bit 7 in port 0x70 must a so be zero to enable fhe CPU s NMI input 54 Issue 37 August 1993 Bus Data lt C 10 Decodes c gt Rd Port 1C U26 4LS374 lt gt Mise Controls Enable Data Out Figure 5 These gates provide the input and output bits needed by the rest of this month s circuitry The unused bits wilf come in handy for future projects DOGTEST also accepts a command from the serial port if you press the T key it will stop clearing WatchPending to force a watchdog reset The interrupt handler turns on the left decimal point just before it enters the final loop and the MAX691 should activate Reset about 1 6 seconds later UNMASKING THE NMI By definition the CPU cannot ignore a Non Maskable Interrupt However the IBM PC and its descen dants include circuitry to prevent a signal from reaching the CPU s NMI pin While this may seem contradic tory the system may not be able to start let alone operate correctly with a hot NMI For example if an NMI occurs before the firmware validates RAM loads the stack pointer and sets the NMI vector the system will crash The Computer Applications Journal The CPU can accept an NMI
186. the circuit is unconditionally stable An Official Entry Form must accompany all entries To receive an Official Entry Form and a complete set of contest rules write or call Circuit Cellar Design Contest 4 Park St Ste 20 Yeman CT 06066 203 875 2199 ask for Rose Fax 203 872 2204 All entries must be received by September 17 1993 Prizes include 500 for first 200 for second 100 for third and 50 honorable mentions The Computer Applications J our nal Issue 37 August 1993 2 5 Real world Macintosh A Mac SCSI interfacing primer For all those who think the Macintosh isn t a viable platform for interfacing with the real world they haven t explored the use of its SCSI bus Join Marc as he begins to explore the world of Mac based SCSI 26 Issue 37 August 1993 FEATURE ARTICLE Marc Bumble here are plenty of hardware design projects centered round the parallel ports of the IBM PC and IBM compatibles Therefore PC compatibles have been the machines of choice for hardware projects However the system soft ware and the user interface available on the Apple Macintosh computers make them an attractive alternative platform for computer automation applications In this article will present a first step towards uniting the Macintosh with user created periph eral projects THE MACINTOSH INTERFACE This article presents a paralld interface connected to a Macintosh SE The parall
187. to 206 435 0253 307 N OLYMPIC SUITE 201 ARLINGTON WA 98223 USA 206 435 8086 FAX 206 435 0253 a a ee DOS and Microsoft are registered trademarks of Microsoft Corporation State_______zip Fax ae on oe a on The Computer Applications J ournal circuit resembles the one based on the p channel driver THE WELL CONDITIONED BATTERY Maximum battery capacity and cycle life are both dependent to a great degree on properly limiting heating during charging This limiting can be achieved by using a fast rdiable method of minimizing overcharge at fast charge rates In the case of NiCd and NiMH batteries the method used to apply the constant current charge can also affect the overall charging efficiency Generally a higher charge rate is more efficient Keep in mind that NiMH batteries don t take kindly to unnecessary overcharge When using constant current charging a current is continuously applied throughout the charging phase Charge acceptance which is charge efficiency is enhanced by charging at rates as high as the particular battery type will allow Of course this high rate must be cut back as soon as a full charge is reached Ultimately continu ous charging causes polarization in the electrolyte which increases battery resistance With this increase in resistance a higher voltage is required for a given charge rate and this in turn contributes to cell heating Intention ally discharging a N
188. tuation of other devices or the presentation of additional images on the screen This is especially usable for handicapped persons to control their environment Other uses include operator interfacing with workstations cockpit controls and in industrial environments 5 126 731 19920630 Cromer Jerry E Jr SC 3 229 059 3 848 249 3 911 316 4 207 959 4 298 863 4 453 043 4 562 432 4 567 479 4 706 067 4 746 913 4 865 610 4 871 154 4 979 094 Pneumatically controlled user operated switch interface A pneumatically controlled user operated switch interface which allows a physically disabled person to operate electronic equipment such as a computer television video cassette recorder and a remote control includes apparatus providing at least one airway passage first switching circuitry for producing a plurality of switching signals and having at least one pneumatic switch responsive to air pressure in at least one airway passage second switching circuitry settable in first and second switch positions for selectively connecting each of the plurality of switching signals to selected inputs of the electronic equipment as the electrical input signals and user activated apparatus for setting the second switching circuitry in the first and second switch positions The switch interface can operate a plurality of computer input devices to allow a physically handicapped person to use commercially available software packages message which mig
189. u know how many data bits are between the start code code end code or LL LOXXXXXXXXXXXKXXXX1000 scheme fo frame the data and to reject false readings data end 00 0 Figure 5 in th simplest data format the upper track s used for data while the lower track contains clock pulses and end codes especially since the data may contain a sequence that looks like a start or end flag or you take the complement of each data bit in which case three sequential marks or spaces are not legal Figure 5 shows the simplest data format using the lower track for the clock and the upper track for the data In this format the top track is searched for data when the bottom track loses signal hits a nonreflective black mark To keep the bidirectional benefit of the swipe input the format of clock to data width is 1 3 The data must extend beyond both ends of the clock mark to assure legal data recognition independent of which direction a clock edge is encountered This also increases the need for perfect alignment Figure 6 illustrates this technique of data encoding for 1 and 0 data bits used the code in Listing la to print clocked bar codes on my HP Laser et Series II Run the program in Listing Ib to poll the PC s joystick port and display the received data bit sequences If the start code data and end code are received as expected a beep declares an accepted swipe Bit errors are displayed as
190. ugh yet to obey the SCSI protocols it will likely violate the protocols thus rendering the hard drive inacces sible In this article will present a rudimentary SCSI test circuit and the software used to drive this hardware The project was built and tested using a Macintosh SE cannot guarantee it will work with other models however took care to make the code portable to other Macintosh modas EXPERIMENTAL SETUP The easiest method of learning about SCSI is to examine the 5380 SCSI interface chip This chip is manufactured by several vendors including NCR and National Semicon ductor To aid in user feedback used 10 segment bargraph displays mounted in 20 pin DIP sockets also added DIP switches to control the 5380 s port control and address lines Figures 1 and 2 show the schematic of my test bed It allows me to control address and data lines so that I can fully test the interface chip s features and functions On this first go around the circuit is set up so you must manually control each of the 5380 s processor bus lines which means flipping switches on and off in a very specific order that 1 11 describe as go along Once you re comfortable with how the chip works you can add more intelligence such as A total of 18 lamp indicator circuts and 18 sets of line Figure l The 5380 chip can be installed so each pin is discretely pulled active The bus lines are pulled low using the DIP switches co
191. ur incoming lines Vernon Connecticut This month we re going fo start off with a discussion of relativity and time What does Einstein have fo do with computer applications Read on fo find out Next we look at some simple methods for defecting the zero crossing of an AC signal Finally we move info automotive data collection and some of the hazards associated with automotive electronics though witha twist It s all a matter of time Msg 11519 From TERRY NORRIS To ALL USERS At work we recently took shipment of an HP cesium beam frequency standard It had an option that took the accuracy of the 10 MHz output to 10 I think The specifications for this device are incredible but it raises a question In A Brief History of Time Hawking says that time is relative to a viewer and his gravitational field He even says an early experiment about two clocks one at the base of a water tower and the other at the top showed that the one closer to a gravitational field ran slower than one farther away He later says that without this knowledge we couldn t have satellites because of the time differences between Earth stations and the satellites Is it valid to have a superstable NIST traceable cesium beam with such precision and a possible source of error due to local variations in gravity greater than the precision What are the errors introduced due to gravity guess will have to make a small list of things believe
192. utting down the system to prevent damaging depletion of the battery With NiCd and NiMH batteries the voltage drops like a rock as it approaches the end of discharge voltage whereas lead acid batteries approach this threshold more gradu ally In both cases however the levels are clearly defined You also should factor self discharge into the equation if the system is to remain idle for periods of time Self discharge usually amounts to 1 per day for NiCd batteries and about 2 per day for NiMH types but these levels do vary over temperature Charge acceptance can also undergo a great deal of change depending on cell type and charge rate and temperature Finally as if that s not enough realize that the charge cycle may be terminated prematurely resulting in a partial recharge Even if you manage to get it right you might have to contend with someone replacing the battery determine the end of charge point accurately for purposes of charge termination Although this is true if and blowing the whole deal For this reason if the battery is not captive to the electrical instrument the capacity the gas gauge register somehow lost synchronization with the battery serious problems could ensue Because with DOS ES SERIE STENT RED EM Real Time Multitaskin ORAL A TERRES Ne kT Shay ene Sie for Microsoft C Borland C Borland Turbo Pascal REE e RES aes ASR OR Tae Develop Real Time Multitasking Applicat
193. x 5ns PALs ea e Free software updates on BBS Powerful menu driven software 400 MHz LOGIC ANALYZER up to 128 Channels up to 400 MHz 16K Samples Channel Variable Threshold Levels 8 External Clocks 16 Level Triggering Pattern Generator Option 799 LA12100 100 MHz 24 Ch 1299 LA32200 200 MHz 32 Ch 1899 LA32400 400 MHz 32 Ch 2750 LA64400 400 MHz 64 Ch 200 MSa s Digital Oscilloscope Price is Complete Pods and Software included Starting at 1599 with Pods amp Software 200 MSa S Sampling Rate 2 Analog Channels 2ch Digital Osciloscope 8 Digital Channels 8ch Logic Analyzer 125 MHz Single Shot Bandwidth 4K Samples Channel Analog amp Digital Call 201 808
194. y of users deemphasizing words based on syntactic consider ations and inserting pauses to enhance intelligibility ee TALK Patent Number Issue Date Inventor s Assignee US References Title Abstract Patent Number Issue Date Inventor s State Country US References Title Abstract 4 950 069 19900821 Hutchinson Thomas E University of Virginia 3 986 030 4 623 230 4 648 052 4 836 670 Eye movement detector with improved calibration and speed A system for eye movement detection is disclosed that utilizes an infrared light emitting diode mounted coaxially in front of the lens of an infrared sensitive video camera for remotely making images of the eye of a computer op erator The reflected light causes bright eye effect which outlines the pupil as brighter than the rest of the eye and also causes an even bright small glint from the surface of the cornea The computer includes graphic processing which takes a video image digitizes it into a matrix of pixels and analyzes the matrix Using special algorithms the analysis calibrates the system to provide a highly accurate resolution and has a quick scan technique to rap idly determine the location of the pupil s center and the location of the glint relative to each other and with this in formation determines where the eye is gazing If the eye gaze is for a predetermined time at images in selected areas on the computer screen the area is selected and results in ac

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