Its not pretty, but its a start. Here is an example for implementing simple MIDI input to control a synthesizer.
Downloads:
It uses UART1 to recieve the MIDI input. The UART1 receive pin (RXD1) is P0.9, on the front of the critter. The MIDI spec requires opto-isolated input, so we use this circuit:
The software example is a 4 voice FM synth. Two knobs are also connected to AD1.4 and AD1.5 to control harmonicity and modulation index of the synth.