Post by thread:mchp and esd?

Truncated match.
PICList Thread
'mchp and esd?'
1997\12\06@162025 by Bordogna, Raymond A

Hi All. Is it *necessary* to use a ground strap when experimenting with pic chips? TIA, Ray

1997\12\06@163936 by William Chops Westfield

Is it *necessary* to use a ground strap when experimenting with pic chips? It is NECESSARY to avoid static damage to the chip. Personally, I think there are a lot of ways to do that that do not involve a ground strap, but the ground strap is what official ESD procedures are likely to require. BillW

1997\12\06@171905 by Andy Kunz

>Is it *necessary* to use a ground strap when >experimenting with pic chips? No, in fact we often plug them into a powered-up circuit without a problem. "Your mileage may vary." Andy ================================================================== Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865 Hardware & Software for Industry & R/C Hobbies "Go fast, turn right, and keep the wet side down!" ==================================================================

1997\12\06@200219 by Bob Fehrenbach

Andy Kunz <spam_OUTmontanaTakeThisOuTFAST.NET> wrote: >>Is it *necessary* to use a ground strap when >>experimenting with pic chips? > >No, in fact we often plug them into a powered-up circuit without a problem. > >"Your mileage may vary." In fact, some of us have done this with the chip rotated 180 degrees with similar results. YMMV -- Bob Fehrenbach Wauwatosa, WI .....bfehrenbKILLspam@spam@execpc.com

1997\12\06@213451 by Reginald Neale

>Hi All. > >Is it *necessary* to use a ground strap when >experimenting with pic chips? > >TIA, >Ray Well, *necessary* probably isn't the right term. Are you launching a space probe or just mucking about with PICs on the workbench? There's a spectrum of tolerable risk. All in all, PICs are pretty rugged, at least as idiot-proof as most of the other chips you might be using. But they're not indestructible. If you shuffle across the rug and pick up your circuit board, all bets are off. A wrist strap, properly used, can help a lot. The best defense is understanding how ESD is generated and controlled. Reg Neale

1997\12\07@051159 by wwl

On Sat, 6 Dec 1997 16:08:00 -0500, you wrote: >Hi All. > >Is it *necessary* to use a ground strap when >experimenting with pic chips? > >TIA, >Ray No, unless you have a lot of synthetic fabrics around... In general if you don't notice static in your work environment, (zaps >from doorknobs etc.) there's no problem. PICs are very well protected by nice big input diodes. ____ ____ _/ L_/ Mike Harrison / White Wing Logic / wwlKILLspamnetcomuk.co.uk _/ L_/ _/ W_/ Hardware & Software design / PCB Design / Consultancy _/ W_/ /_W_/ Industrial / Computer Peripherals / Hazardous Area /_W_/

1997\12\07@150454 by Andrew Mayo

ESD can cause device degradation long before actual failure. It is a common fallacy to assume that because you aren't aware of any sparks etc. that ESD is insignificant. In fact, ESD events which are undetectable at the human level i.e you don't feel a jolt or see a spark, can still cause device damage. Protective diodes are not a panacea for ESD and you should take precautions. If you don't wish to muck around with wrist straps, I have found at least that working without shoes on will minimise static buildup since the leather or synthetic soles of shoes are a major contributor when rubbed across carpet. Of course, avoiding carpet is also good. Interestingly, the problem of ESD damage was first observed, not with MOS devices, but with, of all things, precision metal-film resistors. These were packaged in plastic bags and some lots, mysteriously, were out of tolerance when installed. The problem was traced to ESD damage. As I said, subtle degradation can occur long before complete device failure. {Quote hidden}> ---------- > From: Reginald Neale[SMTP:.....nealeKILLspam.....SERVTECH.COM] > Reply To: pic microcontroller discussion list > Sent: Sunday, December 07, 1997 3:35 PM > To: EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU > Subject: Re: mchp and esd? > > >Hi All. > > > >Is it *necessary* to use a ground strap when > >experimenting with pic chips? > > > >TIA, > >Ray > > Well, *necessary* probably isn't the right term. Are you launching a > space > probe or just mucking about with PICs on the workbench? There's a > spectrum > of tolerable risk. All in all, PICs are pretty rugged, at least as > idiot-proof as most of the other chips you might be using. But they're > not > indestructible. If you shuffle across the rug and pick up your circuit > board, all bets are off. > > A wrist strap, properly used, can help a lot. The best defense is > understanding how ESD is generated and controlled. > > Reg Neale >

1997\12\07@173313 by TONY NIXON 54964

I used the one PIC '84 to develope an ignition module for nearly a year. It took all of the punishment from incorrect insersion into a programmer, countless plug in/out from cct boards, carried about fifty miles from the programmer to the garage, dropped on carpets, the inevitable fingers touching the pins, put in and out of the circuit while powered up. I think the dog even stepped on it once, and it still works today. Its either a tough little chip, or I'm just lucky. It's a real pain in the a**e to track down faults due to static damage, so my suggestion is to take reasonable caution while handling any semiconductor devices. I think even the humble transistor die is so small these days, that it can also be damaged. If you are getting a belt by touching door knobs etc where you experiment then I would definitely take steps to protect the devices. Tony Just when I thought I knew it all, I learned that I didn't.

1997\12\08@004919 by Chris Eddy

Gawd. Why does someone always have to slip a tird in the punchbowl. Just when the thread was going well. Seriously, I would never ask one of my production people to manufacture under the circumstances that I prototype in. I have concrete floors and a mat on my bench. I would always push production to keep studying and to meet the industry acceptable standards. The one problem I have in my lab is this London Fog wool sweater I like to wear. Creates static so bad I have to flick it off. Andrew Mayo wrote: {Quote hidden}> ESD can cause device degradation long before actual failure. It is a > common fallacy to assume that because you aren't aware of any sparks > etc. that ESD is insignificant. In fact, ESD events which are > undetectable at the human level i.e you don't feel a jolt or see a > spark, can still cause device damage. > > Protective diodes are not a panacea for ESD and you should take > precautions. If you don't wish to muck around with wrist straps, I have > found at least that working without shoes on will minimise static > buildup since the leather or synthetic soles of shoes are a major > contributor when rubbed across carpet. Of course, avoiding carpet is > also good. > > Interestingly, the problem of ESD damage was first observed, not with > MOS devices, but with, of all things, precision metal-film resistors. > These were packaged in plastic bags and some lots, mysteriously, were > out of tolerance when installed. The problem was traced to ESD damage. > As I said, subtle degradation can occur long before complete device > failure. > > > ---------- > > From: Reginald Neale[SMTP:nealespam_OUTSERVTECH.COM] > > Reply To: pic microcontroller discussion list > > Sent: Sunday, December 07, 1997 3:35 PM > > To: @spam@PICLISTKILLspamMITVMA.MIT.EDU > > Subject: Re: mchp and esd? > > > > >Hi All. > > > > > >Is it *necessary* to use a ground strap when > > >experimenting with pic chips? > > > > > >TIA, > > >Ray > > > > Well, *necessary* probably isn't the right term. Are you launching a > > space > > probe or just mucking about with PICs on the workbench? There's a > > spectrum > > of tolerable risk. All in all, PICs are pretty rugged, at least as > > idiot-proof as most of the other chips you might be using. But they're > > not > > indestructible. If you shuffle across the rug and pick up your circuit > > board, all bets are off. > > > > A wrist strap, properly used, can help a lot. The best defense is > > understanding how ESD is generated and controlled. > > > > Reg Neale > >

1997\12\08@010206 by Bob Blick

At 12:46 AM 12/8/97 -0500, you wrote: >Gawd. Why does someone always have to slip a tird in the punchbowl. Just >when the thread was going well. I have a video from Apple called "The Shocking Truth" that was required study for me once. Two things I remember from it were the blue auras around the actors that were a special effect designed to help us visualize the problem, and the other is Steve Wozniak going on about synthetic fabrics used in women's underwear. I could tell where that was leading.... Cheers, bob

1997\12\08@041508 by Roberth Lundin

Andy Kunz wrote: > > >Is it *necessary* to use a ground strap when > > >experimenting with pic chips? > > > > No, in fact we often plug them into a powered-up circuit without a problem. > > > > > "Your mileage may vary." Anybody who has implemented a good ESD procedure knows that your return rate on electronic products will decrease due to komponent failures. You will not miss all the strange faults that crop up due to weird components. Most problems of ESD problems will be detected by customers after several month of use. So your comment "Your milage may wary" is very correct. Roberth Lundin

1997\12\08@082658 by Andy Kunz

>after several month of use. So your comment "Your milage may wary" is very >correct. > > Roberth Lundin Roberth, that is _exactly_ what I was commenting on. Many others have now added their input, which (without saying it in the same words) is, "Your mileage may vary." Andy ================================================================== Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865 Hardware & Software for Industry & R/C Hobbies "Go fast, turn right, and keep the wet side down!" ==================================================================

1997\12\08@133000 by Reginald Neale

>>after several month of use. So your comment "Your milage may wary" is very >>correct. >> >> Roberth Lundin > >Roberth, that is _exactly_ what I was commenting on. Many others have now >added their input, which (without saying it in the same words) is, "Your >mileage may vary." > >Andy I highly recommend the book "ESD from A to Z" by Kolyer and Watson. Van Nostrand Reinhold ISBN 0-442-00347-1. It's not a theoretical treatment, it's a collection of practical measurement techniques and production guidelines. Reg Neale

1997\12\08@153106 by Andrew Mayo

[snip] > > > No, in fact we often plug them into a powered-up circuit without a > problem. > You are very lucky. If two pins other than power or ground make contact first, current will flow through those pins, probably through protective diodes to the substrate. If the power source has a low impedance, sufficient current could flow through this path to destroy or damage the chip before proper power connections are made. I definitely would not do this.

1997\12\08@163632 by Andy Kunz

>You are very lucky. If two pins other than power or ground make contact You can operate a PIC by providing power through I/O pins. And if you make your program smart enough, you can even do better. Consider, for example, the following: On an 18-pin PIC, connect /MCLR to Vcc, leave GND unconnected (or tied to your circuit). Pins 9 and 10 will be our NON-POLARIZED power pins (either pin can go either way). PWR_A equ PORTB.3 ; Pic a pin, any pin... PWB_B equ PORTB.4 org 0 bsf RP0 movlw 255 movwf TRISB bcf RP0 btfss PWR_A ; Is PWR_A pin high? goto A_GND ; No, it's ground btfsc PWR_B ; Is PWR_B pin high? goto 0 ; No, something's wrong - power on different pins B_GND bsf PWR_A ; Connect A pin to + supply bcf PWR_B ; Connect B pin to GND supply goto SET_POWER A_GND bcf PWR_A ; Connect A pin to GND supply bsf PWR_B ; Connect B pin to + supply SET_POWER movlw 11100111b ; Turn these pins to outputs movwf TRISB Loop goto Loop ; Put your program here Maybe Mchip doesn't recommend it, but with the lower power it takes to run a PIC and the high current ratings on the pins, it DOES work just fine. Go ahead, try it! Andy ================================================================== Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865 Hardware & Software for Industry & R/C Hobbies "Go fast, turn right, and keep the wet side down!" ==================================================================

1997\12\08@185405 by Steve Baldwin

> You can operate a PIC by providing power through I/O pins. And if you make > your program smart enough, you can even do better. Consider, for example, > the following: OK. I'll bite. WHY would you want to ? Steve.

1997\12\08@204902 by Andy Kunz

>OK. I'll bite. >WHY would you want to ? Dang users who plug things in backwards. Same reason people climb Mt. Everest - because you can. Andy ================================================================== Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865 Hardware & Software for Industry & R/C Hobbies "Go fast, turn right, and keep the wet side down!" ==================================================================

1997\12\08@213831 by Chris Eddy

Y'know, I'm going a little OT, but I had fun once hot plugging a PC peripheral card. It was a simple 8 bit A/D card I designed to go in a product, and pulling it out to change something required shutting down and rebooting into my program that I was writing. And being impatient, I didn't want to wait. So I started hot unplugging and plugging that A/D card I was working on. It was such a simple card, I figured what harm? I got away with it about six times, but on the last try, smoke rose from the IDE hard drive card. I got real lucky, replaced the drive card and moved on with no other damage. Chris Eddy, Pioneer Microsystems Andrew Mayo wrote: > [snip] > > > > No, in fact we often plug them into a powered-up circuit without a > > problem. > > > You are very lucky. If two pins other than power or ground make contact > first, current will flow through those pins, probably through protective > diodes to the substrate. If the power source has a low impedance, > sufficient current could flow through this path to destroy or damage the > chip before proper power connections are made. I definitely would not do > this.

1997\12\08@224058 by Steve Baldwin

> >OK. I'll bite. > >WHY would you want to ? > > Same reason people climb Mt. Everest - because you can. That's a perfectly adequate reason for me. Steve. ====================================================== Very funny Scotty. Now beam down my clothes. ====================================================== Steve Baldwin Electronic Product Design TLA Microsystems Ltd Microcontroller Specialists PO Box 15-680 email: KILLspamstevebKILLspamkcbbs.gen.nz New Lynn, Auckland ph +64 9 820-2221 New Zealand fax +64 9 820-1929 ======================================================

1997\12\09@013532 by paulh

On Mon, 8 Dec 1997, Andy Kunz wrote: > >You are very lucky. If two pins other than power or ground make contact > You can operate a PIC by providing power through I/O pins. And if you make > your program smart enough, you can even do better. Consider, for example, > the following: [ Code to sense power polarity and turn the inputs into outputs deleted.] It isn't necessary to make the power pins outputs. If you don't, I think all that will happen, is Vdd and Vss will be a couple diode drops closer together. This is a bad thing if the absolute values of Vdd and Vss matter, but not bad for all applications. In particular, if the power pins are left as inputs, then you can send data with the power. Just the thing for those simple 2 wire circuits. However, I want to try zero wires and use inductive coupling for power and data. I've been planning on making my own PIC based, inductively powered smart cards since I read the spec sheet for the 12C509. I just need a purpose for such a thing. The thread did inspire me to do some experiments. It looks like a complete card only needs a capacitor or two, a PIC, a zener diode and a printed circuit board. If it isn't based on a 12Cxxx part, it will also need the oscillator parts. So far, I've only tested the power supply part of the system. The PIC blinked an LED to prove that it was alive. I haven't tried to move data from my smart card to the host system. For a real smart card, I would etch a coil around the edge of a card sized printed circuit board. I guess I could get 10 or 20 turns on the coil. I simulated that by wrapping 20 turns of wire around a roll of masking tape. I hooked the coil to a couple of PORT B pins on a PIC 16F84. I put a 1000 microfarad capacitor and a 5.1volt zener diode across power and ground. I used a 10Mhz ceramic resonator. To prove that it worked, I added an LED with a current limiting resistor. I happened to have another PIC on a breadboard conviently hooked up to a motor driver chip. I reprogrammed that PIC to act as a 100Khz oscillator for 250 cycles, then pause for 1 millisecond then repeat. I connected a coil with 10 turns of wire wrapped around another roll of masking tape to the motor driver through a .1 microfarad capacitor. Once the coils were within about a centimeter of each other, my oscilliscope showed 5 volts. I added a 1Kohm resistor load to the circuit. The 1Kohm resistor draws 5 milliamps at 5 volts. 5 milliamps is plenty of power for a PIC. The 1000 microfarad capacitor is way too big for this circuit, but there was one handy on my bench. My web pages got a lot of hits when they made the top 5 useless websites of 1995. I guess I specialize in useless. If I can think of a plausible use for the cards, I'll make a few. All the vaguely usefull things involve some nonvolatile memory, so I'd need to use a 16F84 or an external EEPROM. Assuming I use a 16F84, the card would be a printed circuit board, with a PIC, a resonator, 2 capacitors and a zener diode. Certainly less than $10 each. Using an external EEPROM would make it much cheaper. The reader would be somewhat more complex, but still less than $20. So, anyone got suggestions for usefull things to do with homemade smart cards? -- RemoveMEpaulhTakeThisOuThamjudo.com http://www.hamjudo.com The April 97 WebSight magazine describes me as "(presumably) normal".

1997\12\09@142534 by peter

Why not go all the way get rid of the bridge rectifier and put your program in the main loop spamBeGonepeterspamBeGonecousens.her.forthnet.gr -------------------------------------------------------------------------------- -- -------------------------------------------------------------------------------- -- Andy Kunz wrote: {Quote hidden}> You can operate a PIC by providing power through I/O pins. And if you make > your program smart enough, you can even do better. Consider, for example, > the following: > > On an 18-pin PIC, connect /MCLR to Vcc, leave GND unconnected (or tied to > your circuit). Pins 9 and 10 will be our NON-POLARIZED power pins (either > pin can go either way). > > PWR_A equ PORTB.3 ; Pic a pin, any pin... > PWB_B equ PORTB.4 > > org 0 > bsf RP0 > movlw 255 > movwf TRISB > bcf RP0 > > btfss PWR_A ; Is PWR_A pin high? > goto A_GND ; No, it's ground > btfsc PWR_B ; Is PWR_B pin high? > goto 0 ; No, something's wrong - power on different pins {Quote hidden}> > B_GND > bsf PWR_A ; Connect A pin to + supply > bcf PWR_B ; Connect B pin to GND supply > goto SET_POWER > A_GND > bcf PWR_A ; Connect A pin to GND supply > bsf PWR_B ; Connect B pin to + supply > SET_POWER > movlw 11100111b ; Turn these pins to outputs > movwf TRISB > > Loop goto Loop ; Put your program here > > Maybe Mchip doesn't recommend it, but with the lower power it takes to run > a PIC and the high current ratings on the pins, it DOES work just fine. > > Go ahead, try it! > > Andy > > ================================================================== > Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865 > Hardware & Software for Industry & R/C Hobbies > "Go fast, turn right, and keep the wet side down!" > ==================================================================

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