A dedicated firmware for the M5Stack Tab5 (ESP32-P4) that turns its touchscreen into a class-compliant USB-MIDI grid controller — six playing modes, live value readouts, and a flat, professional UI, with zero DAW-specific lock-in: it's generic MIDI, so it works with whatever you already use (map it in your DAW's own MIDI-learn, the same way you'd map any controller).
All images on this page are real renders of the actual firmware code — the
project ships a native Linux preview tool (tools/build-launchpad-preview.sh)
that links the real rendering source against a software framebuffer, so
these aren't mockups.
- Six modes, one grid: Notes (chromatic, 3 layout sizes), Drums (GM percussion map, auto-selects MIDI channel 10), Faders (CC20-27, relative touch drag, live value readout), XY (CC1 + CC74, a soft glowing touch point, absolute position), Macros (CC102-117, 16 relative rotary knobs), Looper (4-track, records/replays whatever you play in any mode, per-track overdub, visual BPM metronome, can also capture MIDI from a connected host — see below).
- Every control shows its real value and CC/note assignment on screen — no memorizing a mapping, no guessing what a fader is currently at.
- Large, dedicated channel picker (not a cramped always-on strip) — 16 full-size buttons, one tap to switch.
- Panic button — Sustain Off, All Notes Off, All Sound Off, across every channel actually used this session, with send-failure feedback.
- Honest connection state — the firmware only ever claims what it actually knows (USB enumerated vs. not), never implies a DAW is listening just because the OS sees the device.
- Real double-buffered, vsync-synced rendering — no tearing, every frame fully repainted.
- Class-compliant USB-MIDI device, always on from boot. Plug in, your DAW/synth/whatever sees a standard MIDI input — no driver, no DAW-specific plugin.
Boots to a small home screen: open the controller, or check Settings / Diagnostics.
Tap pads to play. The footer's dimension button cycles grid size (8x4 / 8x2 / 4x4); the channel button opens the full-screen picker; Panic clears stuck notes instantly.
Fixed 4x4 GM percussion layout. Switching into this mode auto-selects MIDI channel 10 — the convention essentially every GM/GS/XG-aware synth and DAW expects for drums — still overridable from the channel picker afterward.
Four real touch faders (CC20-27 depending on variant). Press anywhere in a column to grab it, drag to change the value — the fader won't jump just because you touched it.
The whole pad is one continuous surface: X → CC1 (mod wheel), Y → CC74 (filter cutoff/brightness) — both conventional, DAW/synth-recognized CC assignments. A soft glow tracks your touch instead of a hard crosshair.
Up to 16 rotary knobs (CC102-117). Press and drag vertically to turn — relative drag, not absolute angle, since a flat touchscreen has no detents to make angle-based turning reliable.
4 independent tracks. Tap a track button (T1-T4) to select which one Record/Play/Clear target — the other three keep doing whatever they were already doing (playing, recording, paused) regardless of which one is selected, so you can layer tracks: record a part on track 1, let it loop, select track 2, record over the top of it, and so on.
Tap Record to start capturing on the selected track, tap it again to close the loop at whatever length you just played (it starts looping immediately). Switch to another mode and keep playing — the loop keeps going underneath. Tap Record again while it's playing to overdub (layers new material into that track without erasing it); tap again to stop adding. Play/Stop pauses and resumes from exactly where it left off, not from the start. Clear wipes the selected track only.
Each track records whatever you play locally in any mode, and MIDI received from a connected host/DAW while that track is armed — so you can loop something your DAW sends back to the device, not just what you play on the pads.
A BPM readout with +/- buttons and a pulsing beat indicator give a visual tempo reference — purely a feel aid, it does not quantize or snap recording/playback to a grid.
A dedicated full-screen picker (not a cramped strip) — large, legible touch targets for all 16 MIDI channels.
Live hardware/USB health — chip, memory, battery, SD, panel, and detected peripherals.
Exact note/CC numbers, value formulas, and per-mode variant tables:
docs/midi-mapping.md.
| Mode | Message | Notes |
|---|---|---|
| Notes | Note On/Off | Fixed velocity 100 (no pressure sensing on this touch panel) |
| Drums | Note On/Off | GM percussion map, fixed velocity 110, channel 10 by default |
| Faders | CC 20-27 | Continuous, relative drag |
| XY | CC 1 + CC 74 | Absolute touch position, holds last value on release |
| Macros | CC 102-117 | Relative vertical drag |
| Looper | (replays recorded messages) | Not its own message type — re-sends whatever was captured, locally or from the host, into the selected track |
MIDI channel is set entirely by the device (via the channel picker) — the host never negotiates or assigns it; it just listens on whichever channel its MIDI input is pointed at. 16 channels is a hard MIDI 1.0 protocol limit, not a firmware restriction.
Stock ESP-IDF project (tested against 5.5.4):
idf.py build
idf.py -p /dev/ttyACM0 flash monitorRequires a real ESP-IDF 5.5.4 install (. $IDF_PATH/export.sh before the
commands above) — this is a stock IDF project, nothing project-specific
needed beyond that. Known gap worth knowing about: some sandboxed/offline
setups fetch an esptool that predates ESP32-P4 support; if
elf2image/flashing fails with invalid choice: 'esp32p4', you need an
esptool ≥ 5.x ahead of it on PATH.
Iterate on the screen's visuals without hardware at all:
./tools/build-launchpad-preview.sh # writes real rendered frames to launchpad-preview/A perf command is also available over the serial console (any terminal
at 115200 baud) — calls the real draw+present path directly per mode,
unthrottled, and reports timing. Useful if you're chasing a performance
question on your own hardware.
main/launchpad_modes.c/.h— pure pad/CC-index → MIDI-message mapping, no platform dependency at all.main/launchpad_controller.c/.h— portable touch-ownership, note lifecycle, per-mode channel/layout recall, panic, transport-error state, and the Looper's 4-track recording/playback engine. Also platform-free, unit-testable natively.main/launchpad_grid.c/.h+main/studio_ui.c/.h— rendering and hit-testing, built on antialiased proportional type instead of a bitmap font. Every screen does a full repaint every frame it presents — required by the real double-buffered display pipeline (main/display.c); a partial/dirty-region redraw would desync the two alternating hardware framebuffers. Text renders via a composed-glyph blit (su_text()→sgfx_blit()→display.c'sset_window/write_pixels), not one fill call per antialiasing run.main/launchpad_app.c— the one ESP-IDF-specific file: touch polling, frame pacing, host MIDI receive polling (feeds the Looper's host-capture path), wiring the portable controller to real hardware.main/usb_midi_device.c/.h— always-on class-compliant USB-MIDI device (TinyUSB), no host mode of any kind.lib/SIC,lib/SGFX,lib/konsole— vendored hardware-abstraction, graphics, and console libraries (board bring-up, MIPI-DSI panel driving, serial CLI).