parterre
Coming soonA grid of 128 lit keys that runs Lua scripts on the device, or plays norns as a monome-compatible grid. Built on FREEPOET's Open Grid kit today.
parterre
A grid controller of 128 lit keys that runs Lua scripts on the device, and also plays norns and serialosc as a monome-compatible grid. parterre is the firmware and its tools: it runs on an RP2040 and today drives FREEPOET’s Open Grid kit. Other keypad boards can become its backends later.
Status: in development. The firmware runs and is tested on a Seeed XIAO RP2040 without keypads (the scripts, USB MIDI, switching modes); testing with the keypad boards and on norns is next. It was called Open Grid Controller until November 2026; from firmware og-0.3.14 it shows up on USB as parterre.
The hardware
parterre runs on FREEPOET’s Open Grid kit: two 8×8 FREEPOET keypad boards side by side make a 16×8 grid, with an LED under each key (16 levels of brightness), read by an RP2040-Zero, in a 3D-printed low-profile case. The kit, its boards and its case are FREEPOET’s design; see their repository for the parts and the assembly.
The firmware reads the keypads through a small layer of its own, so other keypad hardware (other sizes, or boards such as denki-oto’s mechatrellis) could become further backends.
Two modes
parterre has two modes and stays in the last one you chose, even unplugged.
| mode | status LED | shows up as | use it with |
|---|---|---|---|
| iii (default) | green | USB MIDI and a serial console | greenhouse to write and upload Lua scripts; the scripts then play any DAW or synth over USB MIDI on their own |
| monome serial | blue | a monome grid | norns directly, and Max/MSP, Pure Data, SuperCollider, VCV Rack or TouchDesigner on a computer through monome’s serialosc |
To switch:
- Top-left key: hold it while plugging in. When switching to iii, keep holding for about a second (the top row fills up) to also skip the start-up script.
- BOOT button: hold it for 2 seconds while running (the LED turns magenta); it switches and restarts.
- From greenhouse: type
og_set_mode(1)for monome serial,og_set_mode(0)for iii.
Scripts in iii mode
In iii mode the grid runs monome’s iii: Lua scripts stored on the device decide what each key does and what lights up. Scripts written for monome’s own iii grids run unchanged.
Open greenhouse.vfmod.com in Chrome, Edge or Opera and connect over USB. greenhouse has a console that talks to the grid live, an editor, a view of the grid that mirrors its LEDs and plays its keys from the screen, a MIDI monitor, and graft, a patch editor that wires grid widgets (buttons, faders, a step sequencer, a keyboard, ripples) into a script without writing code.
A good first script is many-roads, a launcher that lights one key per script on the grid.
When something goes wrong
- A script that hangs: if the grid stops responding for 8 seconds, a
watchdog restarts it. If it hangs again within 30 seconds, the next start
skips the start-up script (status LED amber) so you can fix it from
greenhouse, which shows a
watchdog:line when it connects. - Skip the start-up script yourself: press BOOT while the LED is cyan, during the first second after plugging in (the LED turns amber).
MIDI to hardware (DIY)
Every MIDI message a script sends over USB also goes out a pin at MIDI speed, so with a 3.5 mm TRS jack and two resistors the grid can play a synth from a USB power bank, no computer. The wiring is in the repository’s README.
Updating the firmware
When the grid connects, greenhouse checks for a newer firmware release and
offers it. To install one: hold BOOT while plugging in, so the
grid shows up as an RPI-RP2 drive, and drag the .uf2 file for your board
from the releases
onto it. Your scripts are kept.
Credits
parterre’s iii firmware is GPL-3.0, built on monome’s iii. The Open Grid kit, its keypad boards and its enclosure are by FREEPOET.