fm1-chord

A custom firmware that turns the M-VAVE FM-1 pocket synth into a chord-machine style instrument. Built on Felucca. Clean-room: nothing from any other instrument's firmware.

White keys play chords, then strum them. The seven white keys at the left are the scale degrees in the current key and scale, so every chord fits: the first is I, the next ii, up to vii. The nine white keys to their right are a strumplate, as on an Omnichord: each plays one note of the chord last played, rising from key to key, so a swipe across them strums it. In LEAD every white key is a note of the scale instead, up from the tonic, as many at once as you hold. The screen names the chord (or the note) and shows it on a piano; at rest it shows what every key does.

Black keys change them. The eight black keys of the middle octaves are the chord machine's joystick directions (7ths, 9ths, sus, dim, aug, borrowed chords, in four tables); F#3 cycles the inversion (C, C/E, C/G), G#3 locks a change to a key, A#3 holds. With BASS on SLASH (the default), the key held first is the bass and the next one the chord: Em/C.

Everything else a chord machine does: Play, Strum, Lead, Drone, Arp, Repeat, a 16-step chord sequencer, drum pads, 56 drum loops, a 4-layer looper, a mixer, Chord Hiro and the Ear Trainer; 37 sounds (36 classic ones, plus an acoustic guitar for leads), 7 envelope presets, reverb, delay, chorus, flanger, tremolo, vibrato, glide, drive, tape, stereo, a filter wheel; key, scale, bass, voices, voice leading; four presets; MIDI in and out. Only the mic features and Bluetooth are missing.

Controls. Three menus on three buttons, colour-coded: SCL key (grey), FX sound (yellow), EDIT mode (red), SAVE presets. The PRESETS and ALGORITHM knobs pick the sound and the mode from a list, ENV and LFO open theirs, KNOB 1 to 4 are filter, resonance, attack and release with the value shown as you turn (KNOB 4 sets an effect's amount on its row in the sound menu); tempo is on the mode menu and EDIT tapped three times. Chords over drums: record the drum loop into a looper layer; the drum screens show the loop to time it. Your settings come back after power-off. HOME held gives you Felucca's full synth underneath.

Status: running on an FM-1 (installed over USB-MIDI with tools/fm1_install.py, 28 % CPU at idle) and tested on the host simulator. It also runs in the FM-1 emulator with a patch set on its released build that adds the knobs and WAV recording: tools/emulator/run.sh fetches, patches, builds and launches it. Factory reset: hold HOME + SAVE while powering on, or factory yes on the USB console. Spec and notes in spec/docs; build, flash and the findings on the unit in spec/docs/05-dev-setup.md and spec/docs/11-hardware-findings.md. GPL-3.0, as Felucca.