James Newtons Massmind wrote:
> Everything looks good, and it makes it all the way through the
> programming cycle, but when I try to verify, the unit always shows 3FFF
> for each program memory location in the chip except for the first
> location which always shows 2800 (and the first instruction in the
> program is 2828). The Voltages shows around 5 volts (4.99 to 5.22) and
> the VPP at 12.73 to 14.5
>
> I've tried different power adapters (all 9vCD out at .5 amp or better)
> one 12VDC 800ma (little warm on the 7805)
>
> This is my second '877. I don't know if its good or if the chip itself
> has been fried.

I would first try to remove the target circuit as one of the variables.  Set
up a 16F877 hooked only to the RJ-12 connector, power and ground, and the
PGM pin tied low.  Also put a 22pF cap to ground on the PGC and PGD lines
close to the target chip.  If that works, slowly migrate to your circuit to
see what causes it to fail.

If that doesn't work with several 16F877s then you've got a pretty good case
to call Microchip and ask for a replacement ICD2.  Force MPLAB to reload the
ICD2 "operating system" first though to see if that fixes anything.

I've found Microchip to be extremely responsive the few times I've had
problems with their hardware.  One time I even told them that I knew we blew
up an ICE-2000 processor module by accidentally applying 12V to it, and I
still had a replacement the next day at no charge.


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