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'[PIC]: how to check if a pic is broken? any experi'
2002\06\12@122409 by personal

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Two of my PIC stopped function, today. I lost them.
All can be programmed and verified OK, one can even write to EEPROM.
But, did not osci and dead fish.

how to check if a PIC is broken? seems PIC is weaker than normal mosfet........

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2002\06\12@164259 by Andre Abelian

picon face
Hi ???

Do this change your configuration to RC and reprogram the pic
And use RC if you got the clock going then you have startup
Problem, crystals, caps etc. After any kind of soldering wash
The board first. Are you using water soluble solder?

Andre Abelian



{Original Message removed}

2002\06\12@165523 by A.J. Tufgar

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I usually setup a pic I know that's working with a simple program like
this:

movlw 0
tris PORTA
tris PORTB
CLRF PORTA
CLRF PORTB

MOVLW b'11111111'
MOVWF PORTA
MOVWF PORTB

loop
goto loop

Now when you try a working pic attach 1led to any pin on porta and
portb.  The working pic should light up each.  A dead pic won't.

For some reason if you do something odd to a pin the whole port tends to
go on the pic.  No idea why.  Anyone?  But usually if one port goes the
other is ok.

This sounds like your problem as pics can still be programed when a port
is blown.  I think this is because the i/o section is blown but I think
there is an internal multiplexer that still allows programing.

Hope this helps,
Aaron

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2002\06\13@015322 by Vasile Surducan

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> Two of my PIC stopped function, today. I lost them.
> All can be programmed and verified OK, one can even write to EEPROM.
> But, did not osci and dead fish.

 external oscillator is the right choice. If no and no take a
slingshot...

Vasile

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2002\06\13@052826 by Tim Forcer
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On Wed, 12 Jun 2002 at 12:24:19 -0400, someone wrote:

>  From:    personal <spam_OUTgxu15TakeThisOuTspamAICOMPRO.COM>
>
>  Two of my PIC stopped function, today. I lost them.
>
>  All can be programmed and verified OK, one can even
>  write to EEPROM.
>
>  But, did not osci and dead fish.
>
>  how to check if a PIC is broken? seems PIC
>  is weaker than normal mosfet........

(Warning - all the following is concerned with PIC'84, although much of it
will apply to other PICs too.)

I wouldn't go along with the original message's last statement - in my
experience PICs are pretty tough little ICs!  We get a lot which are put in
wrong-way-round and the like, and most of them survive.

Simply getting the PIC to program isn't anything like good enough (although
it is obviously very important!).  Programming only exercises three pins.

Generally, what seems to break PICs is similar to what breaks many digital
ICs, namely contention on output pins.  That is, an output pin tries to go
HI when it is connected either to GND or to another pin which is trying to
drive LO.  (Or it's trying to drive LO and is connected to VDD or to
another pin which is trying to drive HI.)  PICs can source/sink a fair bit
of current, and the resultant dissipation in a contention situation is
enough to blow the driver, rendering that pin dead (sometimes the pin can
be used for input, but generally the bondwire goes too, making it open
circuit).

After a lot of messing around, I ended up producing a little unit with an
18-pin ZIF socket, some LEDs, a dc-dc converter, an analogue switch and a
second PIC.  The latter attempts to program the device under test (DUT) -
if programming fails, this is indicated on a LED and the control PIC
stops.  The DUT is programmed to have a 4-bit twisted ring counter pattern
(0000 > 0001 > 0011 > 0111 > 1111 > 1110 etc) on sets of four output pins
at a time, with the pins connected A0 to A4 to B0 to B4 (etc).  The control
PIC monitors the 4-bit set, looking for the right patterns, and gives a
fault indication if the expected patterns don't appear.  Once all four
patterns have been detected (ie each subset of pins has worked OK as an
output), the control PIC gives an "OK" indication.

Source is just over 900 lines of heavily commented assembler - if anyone's
interested it's at <http://www.ecs.soton.ac.uk/~tmf/pic/tester4.asm>.

HTH,

--
Tim Forcer
Department of Electronics & Computer Science
The University of Southampton, UK

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2002\06\13@055359 by Philip Pemberton

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"Tim Forcer" <.....tmfKILLspamspam@spam@ECS.SOTON.AC.UK> said:
> (Warning - all the following is concerned with PIC'84, although much of it
> will apply to other PICs too.)
>
> I wouldn't go along with the original message's last statement - in my
> experience PICs are pretty tough little ICs!  We get a lot which are put
in
> wrong-way-round and the like, and most of them survive.
The only reason I managed to kill two of my PIC16F874s is because my RS232
linedriver was spiking MCLR below ground when the bootloader software issued
a reset. A BC547 transistor and a few resistors cured that slight problem.
The PICs appear to be stone dead though...

> Generally, what seems to break PICs is similar to what breaks many digital
> ICs, namely contention on output pins.  That is, an output pin tries to go
> HI when it is connected either to GND or to another pin which is trying to
> drive LO.  (Or it's trying to drive LO and is connected to VDD or to
> another pin which is trying to drive HI.)  PICs can source/sink a fair bit
> of current, and the resultant dissipation in a contention situation is
> enough to blow the driver, rendering that pin dead (sometimes the pin can
> be used for input, but generally the bondwire goes too, making it open
> circuit).
Very nasty... Which is why I use resistors to pull I/O lines down. The
reason being, if the pin is accidentally set as an output, the resistor will
start dissipating power. If it's left as an input, the resistor just pulls
it up/down. I tend to use SIL resistor packs a lot more than individual 4k7s
though.

> After a lot of messing around, I ended up producing a little unit with an
> 18-pin ZIF socket, some LEDs, a dc-dc converter, an analogue switch and a
> second PIC.  The latter attempts to program the device under test (DUT) -
> if programming fails, this is indicated on a LED and the control PIC
> stops.  The DUT is programmed to have a 4-bit twisted ring counter pattern
> (0000 > 0001 > 0011 > 0111 > 1111 > 1110 etc) on sets of four output pins
> at a time, with the pins connected A0 to A4 to B0 to B4 (etc).  The
control
> PIC monitors the 4-bit set, looking for the right patterns, and gives a
> fault indication if the expected patterns don't appear.  Once all four
> patterns have been detected (ie each subset of pins has worked OK as an
> output), the control PIC gives an "OK" indication.
>
> Source is just over 900 lines of heavily commented assembler - if anyone's
> interested it's at <www.ecs.soton.ac.uk/~tmf/pic/tester4.asm>.
Very nice. I'll save that URL for future reference.

Later.
--
Phil.
philpemspamKILLspamdsl.pipex.com
http://www.philpem.dsl.pipex.com/

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2002\06\13@064531 by Claudio Tagliola

picon face
I recentrly killed one by trying to AD convert something that shouldn't have
been.
It were three wires connected to something completely different (a set of
relay
switches) and it shorted the circuit. The PIC got fried and it died shortly
after.
On top of it all, it burned out two tracks on my PCB, so than one could
almost
be tossed out. Fortunately, those tracks were the reference voltage
regulators,
so a new PIC was still able to handle the AD conversion by turning off the
reference voltages and using the regular voltage for AD conversion.

To make it short, it was pretty obvious it died.

-----Oorspronkelijk bericht-----
Van: pic microcontroller discussion list
[.....PICLISTKILLspamspam.....MITVMA.MIT.EDU]Namens Philip Pemberton
Verzonden: Thursday, June 13, 2002 11:50 AM
Aan: EraseMEPICLISTspam_OUTspamTakeThisOuTMITVMA.MIT.EDU
Onderwerp: Re: [PIC]: how to check if a pic is broken? any experience?

The only reason I managed to kill two of my PIC16F874s is because my RS232
linedriver was spiking MCLR below ground when the bootloader software issued
a reset. A BC547 transistor and a few resistors cured that slight problem.
The PICs appear to be stone dead though...

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2002\06\13@111252 by Lawrence Lile

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Usually I know a PIC is broken because there is a big hole in the side of
it, and a lot of smoke comes out and a loud noise wakes me up.  They seem to
survive almost any other insult.  Oh yeah, except mixing the MCLR and 5V
lines and trying to program them with 14 volts.  Reprogramming them with the
ol' LED blinky program is a sure way to find out if they are dead.  I've
gone back to the LED blinky on sooo many circuits to find out if I have some
basic problem like a dead chip.

--Lawrence

{Original Message removed}

2002\06\13@124531 by Josh Koffman

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I do something similar, but I output a b'10101010' so I can really tell
if the pins are responding and not just shorted.

Josh

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"A.J. Tufgar" wrote:
{Quote hidden}

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2002\06\14@064328 by Peter L. Peres

picon face
>
>To make it short, it was pretty obvious it died.

A helpful failure indicator is built-in. It is activated if you use high
enough current or voltage. The indication is auditive, olfactive and
visual, as well as physical (if a flying piece of the chip hits you). To
achieve activation of these functions, use at least 24V supply. Lead acid
and NiCd batteries are highly recommended. Lacking that use 220V or
better 380V mains.

Peter

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