@@voodoofish, I setup P2.6 & P2.7 as button inputs. I forgot to edit that picture, but I didn't use an LM317 as a regulator. I used a regulator from Texas Instruments, something in 5-pin sot package.
@@grahamf72, thanks for the sample circuit. I looked at the protection diodes built into the microcontroller, and they can drop something like 0.3V but only handle 2-3mA safely. I think I can get away with a 1k/100K divider like your circuit, but ditch the zener that way. Is the mux resistance of the ADC taken into account when processing the result? Does it load the newly created voltage