Hern=E1n Freschi wrote :

> i'm using their [Microchip] bootloader...

I might be missing something, but have you mentioned
anything about a bootloader before in this thread ?

Have you been using that bootloader for any other project ?

Does it have any limitations (some bootloaders put some
restrictions on the application) that might be a problem
for this particular application ?

> and, i don't have the .asm to recompile,

The ASM for the bootloader or for the application ?

> and my
> programmer (noppp) won't let me mess with the config fuses.

You should not "mess" with them. You should verify they are correct
and, if needed, set them correctly.

Have you been using noppp to program the 877A with any
other application (and it worked) ?

Hern=E1n Freschi also wrote :

> ok now I loaded the hex with fpp and it says config word: 3F3A. that
> is 11111100111010. according to the data sheet, the last two bits (10
> in this case) set the osc type. and 10 is HS osc. so I'm in a dead end
> again.

And what about the other config settings ? Have you verified those ?

> the 877 refuses to oscillate even in a "test circuit" (just
> mclr/vdd/vss and the xtal).

"Just" ??? No caps for the crystal ? No decoupling caps between
vdd/vss ? There is no reason at all to describe your curcuit
if you leave half of it out anyway.

> i replaced the 20mhz xtal and it doesn't oscillate either.

Have these 20 Mhz xtals ever been working with *any* PIC ?
If so, you can probably rule out them as a problem.

Regards,
Jan-Erik.




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