Turning a Nanokontrol into a 16 step multitrack midi looper using a Raspberry PI Zero 2

video upload by Floyd Steinberg

"I turned my Nanokontrol into a 16 step multitrack midi looper using a Raspberry PI Zero 2, using WebMidi on Chromium. This is still work in progress, but I was so happy this works I wanted to share it online. ;-)
Hardware used:
PEAK - for the saw wave patch
Orba - Drums
Reface DX - Lead
PI - sequencer

How it works:
The Nanokontrol has 24 buttons, 16 of them are used as "locks" for the 16 steps in a measure. Pressing a key and turning the left knob "locks" a note in place (a midi keyboard can be used, too). Pressing a button and turning the second knob will adjust note length. The right knob will adjust the tempo of the track.

As this is a web app, all the MIDI stuff is "stored" as a DOM element. Each track is represented by an ordered list that's formatted to look like a table. Velocity, note length and pitch are then stored as data parameters.
There's a web worker running in the background which will provide the time, unaffected by what's going on on the web page. That thread will just count up to 16 in the interval deducted from the BPM and then start from the beginning. Each step, the thread sends a signal to the web page to read the next item in the list and send it to the hardware assigned to that track.

To Do:
- performance optimization for PI Zero (it runs pretty stable on anything else ;-)
- SWING :-)
- midi learning for any given controller
- loading and saving tracks as midi file
- on the fly creation of new patterns, copying the one currently played so you can tweak it
- on the fly pattern switching
- track muting

Once this is done, I'll release it for you to use. :-)"

Support: https://www.paypal.me/alexselck