I’m still working on my YM2149 synth project.I’ve added an optocoupler and implemented the MIDI protocol in my arduino code. I added support for lo-fi 4-bit drum samples. This was a well-known hack by Atari ST coders: updating the volume of a channel (set at the max level) at a high rate, like a classic DAC.
More to come. 🙂
Arduino code: http://pastebin.com/BzaMhtuj