multi is a multifunction device whose primary use is that of the midi controller, of very small size. Unlike the latest generation commercial controllers, it has a USB port and two DIN connectors.

It is completely programmable, therefore allows functions that cannot be obtained in a computer-free setup.

multi also has the possibility of being used as a sound generator because it is equipped with a 10-bit DAC converter. It's perfect to explore digital synthesis techniques.

multi hosts a Seeeduino XIAO with a powerful ATSAMD21G18A-MU microcontroller, 6 pots, 2 pushbuttons, 2 Midi DIN connectors and a 1/8' audio connector. The MIDI input is opto-isolated to avoid grounding loops, as required by official specifications.

Bend multi to your needs
You can program your multi as you need, using the Arduino IDE. For example, you can assign multiple MIDI control changes to a single knob and send them to different MIDI channels.
It allows any kind of MIDI filtering and routing operation and it may also functions as a bi-directional USB to DIN converter.
You can program multi as a simple sequencer, algorithmic arpeggiator, aleatoric patch generator or anything else you can think of.

Software
The software is open source and is available in a github repository.
There are already several usable software and the list is constantly expanding:

• synth sequencer three oscillators monophonic synth with embedded sequencer. It receives MIDI clock and note messages
• drone it's a six oscillators drone machine
• euclidean sequencer receives midi clock, start/stop on the MIDI DIN input, generates euclidean rhythmes on the MIDI DIN output
• 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
• fourier 3 voices drone generator, each voice is composed by six oscillators tuned on the harmonic overtones, each voice has six lfos
• cc scrambler generates random synthesizer patch by spitting out random MIDI CC values (preset fucker)
• multimode keep pressed PB1 and PB2 to choose the mode between: synth sequencer, drone, euclidean sequencer, bytebeat player, fourier and cc scrambler
• 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 if you have choosen the DIY kit you may want to use this software to test your build
• fm a simple fm synth
• blink the ubiquitous blink sketch

Sound generation
multi can produce sounds using the Mozzi sonification library written by Tim Barrass or accessing directly to the DAC output.
Here's video showing multi used as a synth with sequencer, the bassline is produced only by multi and his internal sequencer, drums comes from an external drum machine: