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Node.js – RGB LED with WebSocket – Real-Time RGB Control from Browser

Introduction – Why Control RGB LED with WebSocket?

An RGB LED combines red, green, and blue lights into a single package to display millions of colors. When controlled via WebSocket in Node.js, you can change its color in real time from a browser or mobile UI—perfect for smart lighting, IoT dashboards, and interactive art.

In this guide, you’ll learn:

How to wire and control an RGB LED on Raspberry Pi using Node.js
Set up WebSocket communication between Node.js and browser
Send RGB values dynamically and update LED colors instantly
Use onoff and ws libraries for GPIO and WebSocket handling

Hardware Requirements

Component	Description
Raspberry Pi	Any model with GPIO support
RGB LED (common cathode)	Use common cathode type for simplicity
3 x 330Ω Resistors	One for each RGB pin
Breadboard + Wires	For prototyping

RGB LED Wiring Diagram

R (Red) → GPIO 17 (Pin 11) + Resistor
G (Green) → GPIO 27 (Pin 13) + Resistor
B (Blue) → GPIO 22 (Pin 15) + Resistor
Common Cathode (-) → GND (Pin 6)

Use 330Ω resistors on each RGB line to avoid overcurrent.

Install Node.js Packages

npm install onoff ws express

Backend – Node.js WebSocket RGB Control

const express = require('express');
const http = require('http');
const WebSocket = require('ws');
const Gpio = require('onoff').Gpio;

const app = express();
const server = http.createServer(app);
const wss = new WebSocket.Server({ server });

const red = new Gpio(17, 'out');
const green = new Gpio(27, 'out');
const blue = new Gpio(22, 'out');

// Serve HTML UI
app.use(express.static(__dirname + '/public'));

// Handle incoming WebSocket RGB commands
wss.on('connection', (ws) => {
  ws.on('message', (message) => {
    const { r, g, b } = JSON.parse(message);

    red.writeSync(r ? 1 : 0);
    green.writeSync(g ? 1 : 0);
    blue.writeSync(b ? 1 : 0);

    console.log(` Color updated: R:${r}, G:${g}, B:${b}`);
  });
});

// Cleanup on exit
process.on('SIGINT', () => {
  red.writeSync(0); red.unexport();
  green.writeSync(0); green.unexport();
  blue.writeSync(0); blue.unexport();
  console.log(' Cleanup complete.');
  process.exit();
});

server.listen(3000, () => console.log(' Server running at http://localhost:3000'));

Frontend – `public/index.html`

<!DOCTYPE html>
<html>
<head>
  <title>RGB Control</title>
</head>
<body>
  <h2> RGB LED Controller</h2>
  <label><input type="checkbox" id="r"> Red</label><br>
  <label><input type="checkbox" id="g"> Green</label><br>
  <label><input type="checkbox" id="b"> Blue</label><br>

  <script>
    const ws = new WebSocket('ws://' + location.host);
    const sendColor = () => {
      const data = {
        r: document.getElementById('r').checked,
        g: document.getElementById('g').checked,
        b: document.getElementById('b').checked
      };
      ws.send(JSON.stringify(data));
    };

    ['r', 'g', 'b'].forEach(id =>
      document.getElementById(id).addEventListener('change', sendColor)
    );
  </script>
</body>
</html>

Output – What You’ll See

Visit http://<pi-ip>:3000 in your browser
Toggle checkboxes to turn RED, GREEN, and BLUE on/off
LED color updates in real time based on checkbox states

Example:

Red + Green = Yellow
Red + Blue = Magenta
All ON = White

Best Practices for RGB with WebSocket

Practice	Why It’s Useful
Use `JSON.parse()` safely	Avoids crashing on malformed WebSocket input
Add debounce logic (optional)	Prevents flickering on rapid checkbox changes
Use PWM (future upgrade)	For smooth brightness and color mixing
Always clean up GPIO on exit	Frees hardware resources
Run server with `sudo` (if needed)	GPIO might require root permissions

Summary – Recap & Next Steps

Using WebSocket with Node.js and Raspberry Pi, you built a real-time, browser-controlled RGB LED system. This project combines frontend interactivity with hardware control, ideal for home automation and IoT.

Key Takeaways:

Use onoff for GPIO, ws for real-time WebSocket connections
Control RGB LED states via JSON messages from the browser
Sync UI events to GPIO output in real time
Easily extendable to mobile, touch panels, or sensors

Real-world relevance:
Used in smart lighting systems, interactive art, status indicators, and real-time dashboard interfaces.

FAQs – Node.js RGB LED WebSocket Control

Can I control RGB brightness with this setup?
Not with digital pins alone. You’ll need PWM control using pigpio instead of onoff.

How do I access this from my phone?
Use your Raspberry Pi’s local IP, like http://192.168.1.10:3000 over Wi-Fi.

What happens if I check all three boxes?
The RGB LED emits white light (Red + Green + Blue = White).

Can I use sliders for finer color control?
Yes! Add range inputs for R, G, and B (0–255) and use PWM to set brightness levels.

How do I turn off the LED completely?
Uncheck all boxes. The GPIO writes 0 to each pin, turning the LED off.

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