IB Peter Feucht wrote 2011-02-21 13:46:
> no, there is only one initial eeprom write during flashing the PIC, then
> only once again if mode is changed, which usually never happens and if, t=
hen
> months or even years may have gone by. As said, I'm initializing cell #0 =
to
> $00 for mode 1 and that's it.
>
> To answer another question: No, there is only address #0 written and read=
,
> all other cells are unused.

OK.
In that case this is not an issue with "refresh" of the EEPROM.
More like some random failure.

One way (as mentioned in another post) is to have multiple
EEPROM cells that are compared at each read and re-written
if any cell is different from the others.

>
> A question from my side to this: Does "fail" mean here, that the eeprom c=
ell
> is falling back to $FF or is it possible, that it has any random value af=
ter
> "failing"?

Since one EEPROM byte is 8 memory cells, and each of them might "fail"
independent from the others, I gess that you could end up with any
value between 00 and FF.

I take it for granted that your code that write the EEPROM not in any
way can be executed by misstake ?

If one knew that the whole EEPROM address "fails" from 00 to FF,
that could give some input to what is happening. If it was a random
change of EEPROM cells, I would not guess that the whole cell
would change at once.




>
>
> Peter
>
>
> I'm not sure, but did yo ever reply to the question about if there was an=
y
> other writes to the EEPROM during production use ?
>
> One major questions is, does the EEPROM fail during read-only use or due =
to
> missing "refresh" ?
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