We have been manufacturing a product with the 16F876 microcontroller for
several months now. After the product is assembled it is encapsulated into a
polyurethane mold. This, of course, does not allow us to get to the ICSP
port easily, so we wrote a boot loader which we load during assembly then
use to load the rest of the program and to perform firmware upgrades.  Since
the release of the product we have had a few returned with odd, seemingly
unrelated problems.  Usually we can reload the firmware via the boot loader
and the unit begins to function appropriately.  A couple of those have
failed again a few days later with the same problem.   Our guess here is
that the Flash memory is somehow getting corrupted.  We have rewritten the
boot loader to read out the Flash to confirm this, however we have yet to
see the failure occur.  Has anyone seen a similar problem and/or can provide
a solution or a direction to go in.


Michael

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