DRIFT for the M-VAVE FM-1

DRIFT turns the M-VAVE FM-1 into an ambient instrument. A drone sits underneath and follows your chords. Four Euclidean rhythm lanes play soft percussion and make the drone breathe, each lane with its own length so they drift against each other. On top, the white keys are an Omnichord-style strum plate.

It is a fork of FoMni-1 by Charles Vestal, which is built on Felucca by Hügelton Instruments. Everything FoMni-1 does still works.

Installing custom firmware is at your own risk. The web installer can always put M-VAVE's firmware back.

Playing

Control	What it does
Black keys	Chord buttons. The drone follows them. Hold ENV for minor, LFO for 7th, both for m7.
White keys	The strum plate. Each key plucks one string of the chord.
PLAY	Starts and stops the pulse. The drone fades in with it, or whenever a chord is held.
ARP	Chord hold: the chord (and the drone) keep going after you let go.
REC	Sync start: PLAY waits for your first chord.
FX	Drone page, then Texture, then Sound (press again for the next).
SEQ	Pulse page, then Low, Mallet, Shaker, Swell, Rhythm (press again for the next).
HOME, SEL, GLO	Play, Chords, Setup pages. EDIT steps through every page.
SELECT	Tempo.
ALGORITHM	The OM-84 rhythm (silent by default, see Rhythm below).
PRESETS	Transpose.
KNOB 1 to 4	The four values on the screen.
SAVE	Saves. DRIFT also saves by itself a few seconds after a change.

The drone (FX)

Drone page: Mode, Key, Level, Tone.

Mode. Follow: the drone takes its root from the chord button you press and glides to each new one. Fixed: the drone stays on Key (a pedal tone) while its color voice still follows your chords. Off: no drone.
Tone opens the drone's filter, from dark to bright.

Texture page: Glide, Spread, Breathe, Color.

Glide is how long the drone takes to reach a new chord: a quick slide at 0, a slow drift at 100.
Spread detunes each voice's two oscillators and spreads them left and right.
Breathe is a very slow swell in the filter and level, independent of the tempo.
Color brings in a fourth voice on the chord's third (major or minor) above the root, fifth and octave.

The drone uses the Sound page's Chord rev as its reverb send. Turn it up for a wash.

The pulse (SEQ)

Pulse page: Rate (1/16, 1/8, 1/4, 1/2), Tempo, Perc (all percussion), Vary.

Vary humanizes: softer and uneven hits, a few left out, and the mallet straying to other chord tones.

Lane pages (Low, Mallet, Shaker, Swell): Hits, Steps, Rotate, Level.

A Euclidean rhythm spreads Hits as evenly as possible across Steps. Three hits over eight steps is the tresillo (x..x..x.). Rotate shifts where the pattern starts. Each lane has its own length, so a 3-over-8 against a 5-over-16 lines up only now and then.

Low: a soft thump tuned to the chord's root.
Mallet: bell-like pings on the chord's tones, walking up through them. They ring into the reverb.
Shaker: short filtered noise.
Swell: no sound of its own. Each hit opens the drone's filter and lifts its level, then lets go. Its Level knob is Depth.

FoMni-1's pages, still here

Play (HOME): Voice 1, Voice 2, Sustain, Chord level.
Rhythm (SEQ, last): the OM-84's ten rhythms. DRIFT sets Drums to 0 and Auto bass off by default so the pulse leads. Turn them up to layer the two.
Sound (FX, third): Reverb, Space, Width, Chord rev.
Chords (SEL): change any chord button: press it, then turn Root and Type.
Setup (GLO): Tune, MIDI out, Lights.

MIDI out

The strings on channel 1, the chord on 2, the bass on 3, the mallet on 4. Low (note 36) and Shaker (note 70) on channel 10, along with the OM drums when they are up. Clock goes out while the pulse runs.

Getting it onto your FM-1

The firmware has to be compiled with JieLi's toolchain, which only runs on Linux. This repository builds it for you on GitHub.

Put this folder on GitHub as a new repository (public, so GitHub Pages is free).
In the repository, open Settings > Pages and set Source to GitHub Actions.
Push (or open Actions > Build DRIFT > Run workflow). The build takes a few minutes.
When it finishes, open https://YOUR-NAME.github.io/REPO-NAME/install/ in Chrome or Edge, plug in the FM-1 by USB and press Install. The page also has Back to the stock firmware.

The .fwsc file is also attached to every run (Actions > the run > Artifacts) if you prefer the command-line installer: python3 tools/fm1_install.py drift-X.Y.fwsc.

Keep M-VAVE's V15 firmware (FM-1.fwsc, from m-vave.com/download) on your computer as a way back. If an install is interrupted and the FM-1 stays black, see "If the FM-1 does not start" in Felucca's README.

Working on the code

firmware/src/dsp/drift.c is DRIFT's sound: the drone, the four lanes and the swell.
firmware/src/dsp/omni.c is FoMni-1's instrument. It includes drift.c and calls its hooks.
firmware/src/app/ui.c is the panel and the screen, including the Drone and Pulse pages.

Everything except the final package can be built and tested on any computer with a C compiler:

tests/run_tests.sh            # unit tests, the drift test, the whole app in a simulator

build/host/omni_host SCRIPT OUTDIR runs the firmware from a script (tests/scenarios/*.omni) and writes audio and screenshots. tests/scenarios/drift.omni walks through the new pages. build/scenarios/drift-walk.wav is a minute of DRIFT to listen to after the tests run.

Credits

DRIFT's drone and pulse are new. The strum plate, chords, rhythms, reverb, UI and screen-reader support are FoMni-1's, by Charles Vestal. Its waves, drum sounds and rhythms come from Chordian, Jan125's OM-84 emulator (CC0). The platform (hardware layer, USB, update loader, storage, installer) is Felucca's by Leo Kuroshita (Hügelton Instruments), by way of X0X. GPL-3.0-only; see LICENSING.md.

Omnichord is a trademark of Suzuki. M-VAVE and FM-1 are trademarks of their owners. DRIFT isn't affiliated with or endorsed by Suzuki, M-VAVE, Hügelton Instruments or the FoMni-1 project.