ADC problem with PIC16F917

[eetech]

BigW,

I realize the 2.5 is near the limit, but it is the best choice for the project. The correction factor was computed by using several samples to compute the slope of the error. Calling it an offset is bad terminology on my part.

VSS = 5.0v
VREF+ = 2.58v
VREF- = gnd
measured voltages are in the range of 0.2v to 2.0v

[eetech]

As I said, I fully expected someone to point out a stupid mistake on my part.... and I get to be that someone. The problem was the reference itself, it was not stable.
Thanks to everyone who took the time to look at the problem and those who made sugesstions.


Lesson learned: check everything!