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.

Sorry there have been no updates in months. Things have been busy lately, that’s the problem with having a life. I’m only a part-time geek after all.

Since I last did any work on this project, I have upgraded my PC to a Duron 900 and have installed Windows 2000. I am most impressed with the stability of Win2K, I rarely have more than two crashes per week as opposed to about three times a day under Win98.

However, Windows 2000 will not run the NOPPP software which I have been using to download code into the PIC. I suspect the way ports are accessed in Win2K is not backward compatible with Win95.

To cut a long story short, I have found the Linux version of NOPPP works just fine so I’m using that instead. gpasm is a free compiler for the PIC which runs on Linux so I’m all set to continue development without using Windows.

I’ve redesigned the thing again and got rid of the buffer chip. I’m driving the MIDI output directly from the PIC and it works fine. I’ve used a 7 bit bus arrangement to allow all the inputs to share the same I/O pins as the LED display.

One little hitch was the discovery that the big red illuminated push button needs 12 volts to light up. But I’m running everything off 5 volts. So I’ve made a little adapter out of a small piece of veroboard so I can substitute a LED. I tellya these modern LEDs are so bright! I nearly blinded myself messing about with it.