rmteo:

I changed the pot to ten turn 2k ohm, also tried a ten turn 20k ohm. No change, it reads exactly the same as before. The ADC is not reading correct, between 0.000 and 0.063 Vdc in on AN0 the ADC count is 0, and at 2.500 Vdc the ADC count is 505. At 5.000 Vdc the ADC count is correct, it reads 1023. It is strange that the closer I get to Vdd the more correct the ADC gets. This thing should read 1 count for every 4.8 mV, and its not. I have tried using other chips, such as its big brother the 16F876, and its cousin the 16F819.

At first I suspected my Keithley 175, however I have tried other meters and a scope and they all read the exact same as my Keithley.

Thought about ripple, there is about 1mV. If it were reading the ripple I would at least get a count from the ADC. What is bothering me is that I do not get a count from the ADC until I get over 0.063 Vdc at AN0.

Anyone else have any ideas?

Thanks,
Ron