[KenWittlief]

maybe its only a matter of the way you worded your question, but the PIC family of µC have analog to digital converters built in

so the software cannot really 'see' the analog values or signal. You set up the A to D converter to sample the analog data contininously, and then the software will have a stream of digital numbers coming in that represent the analog signal.

Then its up to your SW algorithm to look for zero crossings, peaks, ect in the data and determine what the frequency, amplitude, frequency content.... of the data is.