MicroMIDI takes incoming MIDI and outputs it in various microtonal equal temperaments. To obtain polyphony, each note is individually reassigned and given the appropriate amount of pitch bend on MIDI channels 1 through 8. Therefore each of these channels should be set to the same instrument on whatever device the 201 Pocket Piano is controlling. For the patch to work properly you must set “note-out-enable” to 0 rather than 1 in the midi.txt file that sits within the “pd” folder on your Pocket Piano’s microSD card. I’ve included the proper midi.txt file here if you just want to swap it for the one on your instrument.

This patch assumes the MIDI instrument being controlled by the Pocket Piano is set to the standard pitch bend range of +/- 2 semitones.

Knob 2 sets the number of notes per octave. You can select one of these popular tunings: 5, 7, 9, 19, 24 and 31-tone equal temperament (TET). You might have to use your ears to work out which tuning the knob is set to, but a rough guide would be: below 9 o’clock is 5-TET, 10 o’clock is 7-TET, 11 o’clock is 9-TET, 1 o’clock is 19-TET, 2 o’clock is 24-TET, and above 3 o’clock is 31-TET. If you know anything about the Pure Data programming language it’s a fairly simple matter to substitute your own tunings.

Knob 3 selects the octave for middle C

Knob 4 will send program change numbers 1-128 to each of the 8 channels.

I’ve tested this using the Pocket Piano’s MIDI ins and outs with the Apple DLSMusicDevice that lives in my Mac, and various other software synths that can play multiple MIDI channels at once, as well as a Casio piano via the USB port in the back of the Pocket Piano. It works well in all these scenarios, but I’m noticing that if you mash lots of keys some of the notes will hang. Haven’t found a way to fix it so maybe don’t do that, but if you turn any of the three middle knobs the stuck notes will stop.