> So, let's say I have something run by a battery, and the
> battery voltage
> is starting to drop off.  If I reset the PIC, what does that really
> accomplish?  I would guess that the battery voltage is still
> going to be
> low.

Your example is more of an impending blackout than a brownout :-)

Brownouts are usually when the supply voltage sags out of tolerance but is
expected to recover.  It might be a failure in the mains supply, a poor
contact on a supply wire, or a sudden load applied somewhere else in the
system (you could usually think of it as an occasion which would have been
avoided if the reservoir caps had been bigger!).

With brownout detect, you have a chance of recovering gracefully when the
power comes back, rather than running out of spec for an indeterminate
period.

Your example is actually one of the places where brownout is not
necessarily useful, it can result in the device repeatedly resetting,
letting the battery recover above the threshold, starting to run again,
pulling the battery voltage low etc etc.  My alphanumeric pager does that,
in the final throes of the battery failing, it repeatedly 'reboots', gets
1/2 way through its first beep, pulls the battery down, resets, gets 1/2
way through its first beep etc etc...

Nigel
--
Nigel Orr, Design Engineer                 nigel@axoninstruments.co.uk
Axon Instruments Ltd., Wardes Road,Inverurie,Aberdeenshire,UK,AB51 3TT
               Tel:+44 1467 622332 Fax:+44 1467 625235
                   http://www.axoninstruments.co.uk