some problem with a pic adc

[HenrikOlsson]

If I read the datasheet properly the accuracy specification on the FVR is +/- 3% so you're still within that window.

Vdd must be above 4.75V and there's a comment saying the specification is valid for the industrial temperature range part only. What's your Vdd and exact part number?

Also, are you doing any filtering/averaging in your code? You might benefit from that if you have noise coupled into your signal which your DMM filters out.

/Henrik.

[lutherblisset]

thank you henrik, the averaging seems to be good but today i will try to check the "zeroing", maybe the problem is there. the Vdd comes from a common 7805 and it's something near 4,97 volts....