I have now finished the code. Tested it and after a few bug fixes, everything works just great. The final software is 930 lines of assembler. You can download it here if you want to.
I also learnt how to use ProTel so I could draw up the final circuit properly. Here’s the result. Notice that I’ve got it down to just one chip now, the little PIC is doing everything. It can directly drive the LED and the MIDI output. I’ve used multiplexing to enable it to drive the 7 segment display and read all the inputs. The PIC’s built in timer keeps everything running accurately, all in all, I’m very pleased with the result.
I threw it into a box and its done! You can see in this photo that I also added a second MIDI output.
