RGBPiano

Light up a WS2812 LED strip mounted behind your piano when you play. MIDI from your computer is streamed over WiFi to a Raspberry Pi Zero that drives the strip.

Inspired by onlaj/Piano-LED-Visualizer.

Architecture

  Piano ──USB/MIDI──▶  Host computer  ──WiFi (WebSocket)──▶  Raspberry Pi Zero  ──▶  WS2812 strip
                       (Node + TS)                            (tiny Python driver)
                       • reads MIDI
                       • computes LED frames
                       • serves config web UI
                       • streams pixels to the Pi

Two pieces:

host/ — the brains (TypeScript / Node, cross-platform)

Runs on your computer (Linux/macOS/Windows). Responsibilities:

• Read MIDI from a selected input port (your piano, or a virtual DAW port).
• Own all the interesting logic: note → LED position mapping, invert, start/end range, velocity → color blending, background, brightness.
• Compute the final per-LED RGB frame and stream it to the Pi.
• Serve the Svelte config UI on http://localhost and persist config to disk.

pi/ — the display sink (tiny Python script)

Runs on the Pi Zero. Deliberately dumb: it receives a finished pixel frame and blits it to the strip via rpi_ws281x. No MIDI logic, no color math — all of that lives on the host. This keeps the Pi side ~30 lines and uses the Python that ships with Raspberry Pi OS.

Why "dumb Pi"?

By moving all LED logic to the host and streaming finished frames instead of raw MIDI, we get:

• One typed source of truth for all behavior (testable on the host).
• A trivially simple, robust Pi script.
• No duplicated color/position logic across two runtimes.

Project layout

host/    Node + TypeScript + Svelte: MIDI, LED frames, config UI, Pi streaming
pi/      Python LED driver + systemd unit for autostart

Getting started

Host (your computer)

Requires Node 20+.

cd host
npm install
npm start          # builds the web UI, then runs the host

Then open http://localhost:3192, pick your MIDI input, set the Pi address, and play. Config is saved to ~/.rgbpiano/config.json.

For development with hot-reloading UI on the same port:

cd host
npm run dev        # host + UI on http://localhost:3192

Pi (the LED driver)

Clone this repo on the Pi, then:

cd RGBPiano/pi
./install.sh       # idempotent: installs deps + a systemd service, starts on boot

To update after pulling new code, just run ./install.sh again. To remove everything (service + virtualenv):

./uninstall.sh

Useful checks on the Pi:

systemctl status rgbpiano       # is it running?
journalctl -u rgbpiano -f        # live logs

The LED data pin defaults to GPIO 18 and the port to 3193. Override with the RGBPIANO_GPIO / RGBPIANO_PORT environment variables in the service if needed.

Ports

Port	Where	What
3192	Host	Config web UI + browser WebSocket
3193	Pi	LED frame stream (host → Pi)

Hardware

• Raspberry Pi Zero (W / 2 W) + microSD
• WS2812 addressable RGB LED strip (better strip = better color)
• 5V power supply sized for your LED count
• See onlaj/Piano-LED-Visualizer for detailed wiring.