I made a Mega64 board running at 8MHz and I am using the internal ADC to read the voltage on pin ADC1 only. The voltage on pin ADC1 is between 2-5 volts always. Here is my problem. I quickly made the UART spit out the conversion every 400mSec so I can watch the result. What I am seeing is a stable 2.523 on the pin of the ADC. This voltage is heavily conditioned from an amp circuit so it is dead solid. I'm watching the ADC and it is bouncing between 480 - 487. Your thinking VCC right? I have the ADC reference pin connected to VCC, so any drift is canceled out. So my question is....does this seem to be an acceptable drift, or is there a problem? I was hoping to have more stability, but perhaps this is just the way it is.
Thanks guys. Have a good rest of the week.