I'm looking for a way to read piezo vibrations in a constant stream, both positive and negative AC voltage signals. How would I set that up with the ADC to get the correct readings?
Yes, next - ADC.
You need to calculate resistors so to get into the range of the ADC.
R2 and R3 - determine the amplification of the signal,
U (Pin_5) - shifts the signal to the positive region.