> The ideal design (no parts, or, at least, no additional parts) seems to b=
e
> to use the low voltage detector in the PIC to generate an interrupt and
> save stuff away to eeprom as the power supply dies. The question is
> whether the power supply voltage falls slowly enough to do what needs to
> be done. I've done this in a couple products to save away a few bytes.


Also note that writing data to the EEPROM is one of the more power intensiv=
e
tasks on most PICmicros. As far as I know it involves a charge pump to get
the voltage needed to write to EEPROM as well as circuitry that is usually
not active. When I did tests at lower levels I noticed that writing to the
EEPROM is something that can actually cause brown outs.

Greetings,
Maarten Hofman.
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist