F#&*ing EEPROM again???

Rob Brzykcy cyborg_0 at iquest.net
Tue Mar 21 05:57:37 CET 2000

----- Original Message -----
From: Byron G. Jacquot <thescum at surfree.com>
To: <synth-diy at node12b53.a2000.nl>
Sent: Monday, March 20, 2000 11:14 PM
Subject: Re: F#&*ing EEPROM again???

> >The whole system began to fail 2 days ago. Yesterday it just refused to
> >boot up. Or at least it refused to get past it's initial LED test.
> >Thinking that the problem was something to do with the front panel, or
> >the PSU which is still blowing close to the wind, I pulled the whole
> >apart.
> Quick PSU related question:
> Do you have a brownout detector?  I've had troubles where power
> do funny things to EEPROMS.  If the system isn't held by having reset
> asserted during the power transitions, it can write gibberish into the
> EEPROM.  As the power rails ramp up or down, the program counter can wind
> places it shouldn't otherwise be, with invalid data.
> AVRs are notoriously bad abut this, if that's what you're using.  I'll bet
> others have similar troubles

At GM we had this problem the moment the battery system went into charge
mode. The sudden spike induced from the change in the supply voltage was
enough to throw the PIC into the weeds. But, *why* would his suddenly
*learn* this bad behavior after working for weeks?

This may sound crazy, I know, but once we had a similiar problem occur after
a few weeks. It ended up that there was a little bit of flux residue that
had absorbed moisture over time and became somewhat conductive. It was
enough to cause intermittent problems.


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