I have been using the microphone port of an android phone to read AC voltages (as it is capacatively coupled).
What if I want to read DC voltages?
I have considered...
turning DC into AC via an oscillator
using a PIC microcontroller to read an analogue voltage and send a high/low bitstream to the microphone input containing this information
I think (2) is the best way to go. What is the easiest/quickest/cheapest way to get a PIC to read an analogue voltage and output a bitstream in this way?