multi - midi controller/filter/router, sound generator

multi is an open hardware circuit board hosting a powerful Seeeduino XIAO, 6 pots, 2 pushbuttons, 2 Midi DIN connectors and an audio output.
The Seeeduino XIAO board carries an ATSAMD21G18A-MU which is a low-power microcontroller and has 14 GPIO PINs, a DAC output and one UART interface. To avoid grounding loops the MIDI input is properly opto-isolated, as required by official specifications.

You can program multi as you need, using the Arduino IDE.
On the MIDI side, possible use includes advanced midi controlling, filtering and remapping as well as algorhitmic arpeggiators and aleatoric patch generators.
Since the Xiao board has a DAC, multi can also be used to produce sounds using the Mozzi sonification library written by Tim Barrass or accessing directly to the DAC output.

I’m using it along with my DIY norns and they pair very well.

On the multi github repository you can find the fabrication files, the schematic and the software I’ve written so far:

  • default software, it’s a six oscillators drone machine that is also a midi controller.
  • bytebeat player allows to play algorithmic music with no instruments and no real oscillators but a math expression that creates an audio output waveform as a function of time, processed 8000 times per second. The expression has six parameters accessible through the multi knobs.
  • midi converter is a USB to 5 DIN bi-directional MIDI converter.
  • midi metronome takes the MIDI clock from the 5 DIN midi connector and generates a metronome click on the audio output, to allow acoustic musicians to synchronize their performance to an electronic setup.
  • hardware test use this software to test your build.
  • blink the ubiquitous blink sketch.

Kits and assembled units are available for purchase, please contact me directly and avoid discussion of buying/selling in this thread. Any comments and suggestion will be appreciated.


I love the look of it!

Are there any sound samples available to listen to?

1 Like



Sweet, thank you - nice work!

Hopefully will drop you a line after next $DayJob paycheck lands…


i have to agree
this is pretty cool!