WiFi-connected LED bar display for the hackerspace.
LAN
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Xiao ESP32-C3 Arduino Uno
┌─────────────┐ UART ┌──────────────┐
│ WiFi/HTTP │──────▶ │ LED bar │
│ webserver │ 9600 │ controller │
│ 3.3V logic │ baud │ 5V logic │
└─────────────┘ └──────────────┘
Why two chips? The LED bar needs 5V logic — the Arduino Uno provides that. The ESP32-C3 handles WiFi/Bluetooth but runs at 3.3V, so it can't drive the bar directly. They communicate over UART.
Live at https://0x20.github.io/LED-BARt/
The website/ folder contains a web frontend with a pixel-accurate preview using the same 5x7 font as the hardware. It has three modes:
- Text — type a message (max 19 chars), preview it live, send via HTTP POST
- Effects — animated effects running on the ESP32 itself (scroll, blink, wave, rain, sparkle, Game of Life, inverted, pulse) with adjustable speed — effects persist even when the browser is closed
- Pixel Editor — click/drag to draw pixels directly on the display in real time
The connection indicator shows green when the WebSocket is connected for live streaming.
Send text to the display via the web interface or directly:
curl -X POST http://ledbart.local/text -H "Content-Type: text/plain" -d "HELLO WORLD"Reachable via mDNS at ledbart.local. Max 19 characters — longer text is truncated, shorter is padded with spaces.
| Endpoint | Method | Body | Description |
|---|---|---|---|
/text |
POST | plain text | Send text to display (max 19 chars, 5x7 font) |
/pixels |
POST | 190 hex chars | Send raw pixel data (95 column bytes) |
/effect |
POST | JSON {"effect":"scroll","text":"hello","speed":80} |
Start a server-side effect |
/effect |
GET | — | Get current effect status |
/effect |
DELETE | — | Stop effect, clear display |
/log |
GET | — | View activity log |
/help |
GET | — | API help text |
WebSocket :81 |
binary | 95 bytes | Real-time pixel streaming |
Effects: scroll, blink, wave, rain, sparkle, gol, inverted, pulse
Effects run on the ESP32 and persist without a client connected. Any direct interaction (text, pixels, WebSocket) automatically stops a running effect.
Board: Seeed XIAO ESP32C3 (install Seeed boards package in Arduino IDE)
Libraries:
- WebSockets by Markus Sattler (v2.4.0+)
Built-in (included with ESP32 board package): WiFi, WebServer, ESPmDNS, HardwareSerial
No external libraries needed — uses only Arduino.h.
Disconnect the wire from Uno pin 0 (RX) before uploading, reconnect after.
| ESP32-C3 | Arduino Uno |
|---|---|
| D6 (TX) | pin 0 (RX) |
| GND | GND |
| Folder | Chip | Role |
|---|---|---|
scripts/led_bart_esp32c3_webserver/ |
Xiao ESP32-C3 | HTTP → UART bridge + mDNS (ledbart.local) |
scripts/led_bart_arduino_uno_uart_display/ |
Arduino Uno | UART → LED bar driver (active) |
scripts/gol_ledbar.py |
— | Game of Life via WebSocket (standalone Python) |
scripts/font_preview.py |
— | Preview 5x7 font glyphs in the terminal |
scripts/legacy/led_bart_arduino_uno_og/ |
Arduino Uno | original reference code |