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'How long PIC's life?'
1996\11\14@230844 by anai Anantawatanawitaya

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Hi all,

Does anyone know how long a PIC could works a certain code such as a real
time clock which is never be interrupted or reset until it stops or hangs
by itself?

Let's assume that there is no bug in code at all and power supply is in a
very good condition. Also watchdog is disabled. You may think this is a
strange question but I think it's interesting because I'm developing a
product that has to be powered all the time until user throw it away
because he buys a new model, not because the old one is dead.

Thanks in advance,
Wiriya Sasisakulporn

1996\11\14@234027 by Steve Hardy

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> From: Thanai Anantawatanawitaya <spam_OUTthananTakeThisOuTspamMOZART.INET.CO.TH>
> Hi all,
>
> Does anyone know how long a PIC could works a certain code such as a real
> time clock which is never be interrupted or reset until it stops or hangs
> by itself?
>
> Let's assume that there is no bug in code at all and power supply is in a
> very good condition. Also watchdog is disabled. You may think this is a
> strange question but I think it's interesting because I'm developing a
> product that has to be powered all the time until user throw it away
> because he buys a new model, not because the old one is dead.

It will go forever.  Well, at least until the chip wears out.  Yes,
there is a phenomenon in which the metallisation on the die surface
migrates slowly in the direction of sustained current.  Also, the
dopants in the semiconductor junctions will slowly diffuse from thermal
effects.  Hard radiation also degrades the die.  Atomic bombs going off
in the ionosphere or nearby will probably snuff it.  However, except
for The Bomb, for your purposes these processes will not affect the
chip until _way_ past your next product release.  If The Bomb goes off
then you will have other things to worry about.

Regards,
SJH
Canberra, Australia

1996\11\15@000624 by Giles L. Honeycutt

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Well, I would say a description of what is critical is important, not
asking how long a brick will stay square.  Under normal operation, I am
sure it will work fine for you, it is not MS Windows95 that likes to
lockup for no real reason.  But anyway, what is critical?, Timing? Data?
Outputs? Inputs?  Once you have figured that out, can implement
fail-safe methods of handling the problems.  A real-time clock/calendar
with a super-cap to back it up is good for keeping time (I use this, it
is good for over a week) , A EEprom for storing critical data, and if
you are worried about data just randomly getting corrupted, you can
incorporate a self test to constantly check memory and fire a reset if
something does change. Well, without a description of the application I
would say I have run out of guesses. (grin)
   Giles L. Honeycutt


Thanai Anantawatanawitaya wrote:
{Quote hidden}

1996\11\15@020841 by Ian Stirling

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>
> > From: Thanai Anantawatanawitaya <.....thananKILLspamspam@spam@MOZART.INET.CO.TH>
> > Hi all,
> >
> > Does anyone know how long a PIC could works a certain code such as a real
> > time clock which is never be interrupted or reset until it stops or hangs
> > by itself?
> >
> > Let's assume that there is no bug in code at all and power supply is in a
> > very good condition. Also watchdog is disabled. You may think this is a
> > strange question but I think it's interesting because I'm developing a
> > product that has to be powered all the time until user throw it away
> > because he buys a new model, not because the old one is dead.
>
> It will go forever.  Well, at least until the chip wears out.  Yes,
> there is a phenomenon in which the metallisation on the die surface

While it may do, it may at any time be hit by a decay product of some
radiactive isotope in the packaging, or a cosmic ray, this may cause anything
from a change in a register (internal or user) to altering eeprom/eprom/rom

The first ones on the list are more probable     How often will it happen?
I doubt microchip charecterises chips for this, the only way would be to
impact the chip with cosmic ray like events, and see what average interehaction
rate there is.

{Quote hidden}

--
Ian Stirling.                        |  http://www.mauve.demon.co.uk/
AKA Caeser, Bolonewbie.              |  With information on the PDA I'm making.

1996\11\15@152118 by Craig Knotts

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    It's probably safe to assume the PIC will keep running until the rest
    of the circuit (particularly switches, relays, connectors) have worn
    out, assuming that the part is not subjected to overstress.  At
    reasonable temperatures, humidity, and vibration levels, it should
    last darn near forever.


______________________________ Reply Separator _________________________________
Subject: How long PIC's life?
Author:  thananspamKILLspamMOZART.INET.CO.TH at internet
Date:    11/15/96 10:37 AM


Hi all,

Does anyone know how long a PIC could works a certain code such as a real
time clock which is never be interrupted or reset until it stops or hangs
by itself?

Let's assume that there is no bug in code at all and power supply is in a
very good condition. Also watchdog is disabled. You may think this is a
strange question but I think it's interesting because I'm developing a
product that has to be powered all the time until user throw it away
because he buys a new model, not because the old one is dead.

Thanks in advance,
Wiriya Sasisakulporn

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