Had a problem recently where the EEPROM data on a PIC got corrupted during 
operation.  I feel strongly that a power-surge/issue caused this.  Is this 
really possible?  Or are there other conditions that can cause this?

BTW, here's why I feel that power caused it... the PIC stores counts of events 
that occur periodically.  Each new data point is higher in value than the 
previous one.  The EEPROM area is virtually divided into multiple groups, and 
the groups are written to sort of like a circular buffer.  When writing a 
group, each byte is written and then a checksum is written in the appropriate 
location for that group.  After the last group is written, the first group is 
re-used.  There are something like 20 groups of 4 bytes each.  If power is 
switched off and back on, all EEPROM data is scanned as groups for valid data 
(using the checksum) and the highest valid value is where the counting 
re-starts for future events.  A loss of 1 occassionally due to power being 
switched off during a write is okay.

This has been running successfully for some weeks, but when the EEPROM got 
corrupted, there was a lot else on that power line, being switched on an off.  
And all of this occuring on a breadboard with a pretty crappy old AT 
power-supply that can't regulate 5V properly to save it's life.  It varies 
from 4.6V to 5.1V regularly depending on load.  As soon as I saw that data 
get screwy (based on display output), I read-back the contents of the EEPROM, 
and all locations were screwed up.  And the time between the noticed 
corruption and the read-back was small enough to allow only 1 or 2 events to 
occur.  The remaining data groups should've been valid.

Any idea what could cause this, and more what else I should be doing to 
protect against this in the future?

Cheers,
-Neil.


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