That initially was my thought, but my dilemma is the initial ADC supply will be 5 volts from the VR, but my input is 12 volts. I was thinking of putting a voltage divider on the input wire to supply 5 volts to the ADC pin like you show, but not sure if that would work right or what might happen when the ground signal is applied. Was thinking to maybe add a 5V Zener, but I think when the input is "floating", the ADC will find ground through the Zener.

By the way, does ADC code run in the background like an interrupt would, or does it run in sequence like any other code? Reason being is that I am running other code on the chip right now, so that would have to be one more routine to run.

Thanks,
Tony