Searching \ for 'mchp and esd?' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: techref.massmind.org/techref/index.htm?key=mchp+esd
Search entire site for: 'mchp and esd?'.

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

flavicon
face
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

face picon face
   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

flavicon
face
>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

picon face
Andy Kunz <spam_OUTmontanaTakeThisOuTspamFAST.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     .....bfehrenbKILLspamspam@spam@execpc.com

1997\12\06@213451 by Reginald Neale

flavicon
face
>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

picon face
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 / wwlspamKILLspamnetcomuk.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

flavicon
face
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}

1997\12\07@173313 by TONY NIXON 54964

flavicon
picon face
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

flavicon
face
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}

1997\12\08@010206 by Bob Blick

face
flavicon
face
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

flavicon
face
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

flavicon
face
>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

flavicon
face
>>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

flavicon
face
[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

flavicon
face
>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

flavicon
face
> 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

flavicon
face
>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

flavicon
face
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

flavicon
face
> >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: KILLspamstevebKILLspamspamkcbbs.gen.nz
New Lynn, Auckland           ph  +64 9 820-2221
New Zealand                  fax +64 9 820-1929
======================================================

1997\12\09@013532 by paulh

flavicon
face
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?

--
RemoveMEpaulhTakeThisOuTspamhamjudo.com  http://www.hamjudo.com
The April 97 WebSight magazine describes me as "(presumably) normal".

1997\12\09@142534 by peter

flavicon
face
Why not go all the way get rid of the bridge rectifier
and put your program in the main loop

spamBeGonepeterspamBeGonespamcousens.her.forthnet.gr

--------------------------------------------------------------------------------
--
--------------------------------------------------------------------------------
--
Andy Kunz wrote:

{Quote hidden}

on different pins
{Quote hidden}

More... (looser matching)
- Last day of these posts
- In 1997 , 1998 only
- Today
- New search...