GR!MM
GR!MM turns the FM-1 into a four-track drone and atmosphere machine: seven sound sources, long dark effects, a 64-step sequencer per track, one-key chords, an arpeggiator, song mode and live performance tricks.
- Custom firmware
- Stable
- Medium brick risk
Source codeWebsite: grimmbient.github.io
This project hasn't been claimed by its maintainer yet, so its details come from the community. Is it yours? Claim it
GR!MM 1.0, the first public release: a dark ambient, dungeon synth and deathdream firmware for the M-VAVE FM-1.
Install: pick GR!MM on the FM-1 Firmware Hub in Chrome or Edge, or download
grimm.fwsc below and install it with py tools\fm1_install.py grimm.fwsc. Installing firmware is at your own risk;
the hub's Rescue page brings a stuck FM-1 back.
Try it first: the demo runs the same firmware in your browser. The editor edits sounds live on the FM-1, loads samples and makes backups.
What's in it:
- Four tracks with six shared voices and seven sound sources: VA, 6-operator FM (fully editable on the FM-1), SAMPLE, VOICE, WHEEL, PHYS and PHASE
- 40 factory sounds and 64 slots for your own, with names
- Four factory samples (URCHIN, LEAVE, NIKOLAI, M-SOFT; CC0), written into empty sample slots at the first start. RESTORE FACTORY SAMPLES is on SYSTEM 2 and in the editor
- Effects: TAPE, GRAIN with FREEZE, DELAY, and SPACE (reverb up to ~32 s, and infinite)
- Per track: envelope, LFO, filter, scales, one-key chords, arpeggiator, latch
- A 64-step sequencer per track with chance, ratchets, note lengths, step locks and pattern tools
- Song mode, slots A–D, a performance layer (freeze, throws, tape stop, reverse, filter sweeps, stutter)
- MIDI in and out, MIDI learn, USB audio, autosave, the battery level on HOME
The manual explains every page and combo.
Package identity: FM-1_966. Your sounds, slots, settings and samples are kept when you update.
Free software under GPL-3.0; LICENSE, LICENSING.md and LICENSES.zip are attached. Built on Dinghy (zvenson),
Felucca (Leo Kuroshita, Hügelton Instruments) and SLOOP (isod89).
Before you start
- How hard is it?
- EasyCopy a file or use a web page. No extra software.
- What you need
- A USB or MIDI cable
- Comfort with the command line
- A computer
- Can it break my device?
- Small chance of trouble, with a way to recover.
- Can I undo it?
- The project doesn't say. Assume you can't.
Did it work for you?
Did GR!MM v1.0 work on your M-VAVE FM-1?
No reports yet for v1.0.
One-tap reports from owners. Bricked reports are checked before they count.
Compatibility
Devices: M-VAVE FM-1.
No compatibility information yet.
Getting started
From the project's README ("Install"):
- Open the FM-1 Firmware Hub in Chrome or Edge.
- Connect the FM-1 over USB.
- Pick GR!MM and press install.
Updates appear on the hub automatically when a new release is published here.
If GR!MM isn't on the hub yet, or you want to install a release file by hand: download grimm.fwsc from Releases, then, with Python 3 and py -m pip install mido python-rtmidi:
py tools\fm1install.py grimm.fwsc
Your sounds, slots A–D, settings and samples stay on the FM-1 when you update. If anything goes wrong, the hub's Rescue page brings a stuck FM-1 back.
Risk and recovery
- Brick risk
- Medium
- Requires opening the device
- No
From the project's README ("Install"):
- Open the FM-1 Firmware Hub in Chrome or Edge.
- Connect the FM-1 over USB.
- Pick GR!MM and press install.
Updates appear on the hub automatically when a new release is published here.
If GR!MM isn't on the hub yet, or you want to install a release file by hand: download grimm.fwsc from Releases, then, with Python 3 and py -m pip install mido python-rtmidi:
py tools\fm1install.py grimm.fwsc
Your sounds, slots A–D, settings and samples stay on the FM-1 when you update. If anything goes wrong, the hub's Rescue page brings a stuck FM-1 back.
Releases
| Version | Name | Released |
|---|---|---|
| v1.0 | GR!MM 1.0Latest | 17 October 2026 |
Credits, license and support
- License
- GPL-3.0