Help with ADCin

[mister_e]

Try something, load the PGM pin to gnd with a pull down resistor (says 1K), if it works, then the chances are that your device programmer don't program the fuses properly.

On the other hand, a nasty breadboard could do some problem. Some have broken power strip along the way. It still looks like a bad Vss connection to me.

EDIT: Program your device, but before check the fuses settings in your device programmer software to see if they match your program. If so, program your device... then read it back. Se if the fuse setting remain the same. Case not, throw your device programmer away Nah, sometimes, just a pull down resistor on the PGM pin while programming is needed. Try it!

[RDavid60]

Demon and Steve:

Thanks for the sugestions guys, tried them to no avail.

I don't have a 16F877, but I do have a 16F876. Tried it and it does not make a difference. Also tried a 16F819 it also behaves the same way.

Tried 1k pull down on PGM pin, no difference.

LVP is disabled in programmer. BTW, it's a PicKit 2, I have two of them both program fine. I can change the fuse settings and verify that the changes are making it to the PIC.

Now as to the breadboard. The breadboard that I normaly use is chocked full of another project (thats another story), so I borrowed one form my son, its a cheap-O from Jameco. Now that you bring it up, I'm starting to question if it might be the problem... I'm going to build this circuit up on a custom PCB and see it that solves the problem. Might very well be the culprit.

Very strange that I have to ensure that all pins on PortB are low before the ADC will read below 0.063 Vdc on AN0.

Thanks,
Ron