LED Grid Visualizer

A 32x32 pixel LED grid visualizer that runs in the browser and can drive a physical RGB LED matrix via USB serial.

What it does

• Displays a 32x32 pixel canvas in the browser, styled like an LED screen
• Runs particle animations (shooting stars, sparkles) in real time
• Streams frames over USB serial to a Pimoroni Interstate 75 board driving a HUB75 RGB LED matrix
• Uses Web Serial API (Chrome/Edge) — no drivers or native apps needed

Hardware

• Pimoroni Interstate 75 (RP2040-based HUB75 driver board)
• 32x32 HUB75 RGB LED matrix panel
• USB-C cable to connect the board to your computer

Setup

1. Flash the board

1. Download the Pimoroni MicroPython firmware (.uf2 file for Interstate 75)
2. Hold BOOT on the board, plug in USB — it mounts as RPI-RP2
3. Drag the .uf2 file onto the drive

2. Upload the firmware

1. Open Thonny → Tools → Options → Interpreter → MicroPython (Raspberry Pi Pico)
2. Open interstate75/main.py
3. File → Save As → Raspberry Pi Pico → save as main.py
4. Close Thonny (only one app can use the serial port)

3. Run the visualizer

1. Unplug/replug the board so main.py starts automatically
2. Open index.html in Chrome
3. Click Connect to Interstate 75 and select the USB serial port
4. The animation plays on both the browser and the physical LED matrix

Serial Protocol

Fire-and-forget streaming at 1.5 Mbaud:

Byte(s)	Description
0xFF	Sync byte (frame start marker)
1024 bytes	RGB332 pixel data (1 byte per pixel, 32x32)

• RGB332 encoding: 3 bits red, 3 bits green, 2 bits blue per pixel
• Pixel values are capped at 0xFE so the sync byte 0xFF is unambiguous
• No ACK — the board resyncs on the next 0xFF if any data is lost
• The board expands RGB332 → RGB888 directly into the PicoGraphics framebuffer using Viper-compiled blitting (near-C speed)

Files

index.html              Web visualizer + serial streaming
interstate75/main.py    MicroPython firmware for the Interstate 75