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Christmas project: Control lights with the voice and Raspberry Pi

โณ 3 mins read time

Controlling lights are a good place to start learning electronics. Itโ€™s simple and they have a visual effect that captures people attention. In addition, Itโ€™s Christmas time! So days are shorter and Christmas lights always give a warm sensation.

In this article I will explain how to connect lights into a Raspberry Pi and control them with voice commands.

Christmas tree with lights that are controlled with the Raspberry Pi

Control lights using a relay

I already had a Snips developer kit, so I just need to add two more components:

I had to cut the lights cable and insert then into the relay so that it can be turned on and off with the Raspberry Pi. The final assembly can be seen in the following image.

Lights are powered by a USB cable and connected to the relay so that it can be controlled by the Raspberry Pi

Once the lights and the relay are connected, one can can use a library like nodejs OnOff to turn on and off the relay. The principle is to instanciate a Gpio object and turn it on and off by writing a value 1 or 0 respectively. In addition, I used the documentation examples of the library to create a blinking function to make the relay blink. Here I present you the code of the module that I used:

// relay.js

const Gpio = require('onoff').Gpio;
let LEDPin = new Gpio(12, 'out'); // declare GPIO12 an output

function blinking (blink_time = 2000) {
	startValue = LEDPin.readSync()

	// Toggle the state of the LED
	const iv = setInterval(_ => LEDPin.writeSync(LEDPin.readSync() ^ 1), 500);

	// Stop blinking the LED after blink_time
	setTimeout(_ => {
		clearInterval(iv); // Stop blinking
		if (startValue == 1) {
			console.log("Letting up", startValue)
		} else {
	}, blink_time);

function changeState (arg) {

Turning lights periodically

I wanted to have Christmas lights blinking from time to time and wish Merry Christmas ๐ŸŽ„, so I added a recurrent job that every hour:

  • Tell which time it is ;
  • Wish merry Christmas ;
  • Blink the Christmas lights.

Here you can find the function that I used but the complete code can be found here.

// index.js
const relay = require('./relay');

const job = new CronJob({
  // At minute 0 past every hour from 9 through 21.โ€
  cronTime: '00 9-21 * * *',
  onTick: function () {
	  let currentTime = new Date();
	  SnipsMopidy.speak(`Feliz navidad, son las ${currentTime.toTimeString().substring(0, 2).replace(/^0+/, '')}`);
  timeZone: 'Europe/Paris'

Take a look at the result, the device telling the hour and turning on the lights.

Your browser doesn't support HTML5 video.

Controlling lights with snips

I wanted to be able to control lights using voice commands. I achieved this using Snips. I created an intent lightsOn and lightsOff with some query examples for each one. Then the voice assistant will recognize when someone tells something like โ€œTurn on the lightsโ€.

After that, I updated my assistant code, so that it can handle the case when each intent is recognized. Take a look at the concerned code:

  // ...
  } else if (intentName === 'cristianpb:lightsOn') {
  } else if (intentName === 'cristianpb:lightsOff') {
  // ...

Once again, the complete code can be found here.

The results is that I can turn on and off the lights by using the voice, as you can see in the following video.

Your browser doesn't support HTML5 video.


This is a simple way to control lights using devices like a Raspberry Pi. In addition itโ€™s relatively cheap, I spend less than 6 USD in the lights and the relay. It gives a nice technological addition to Christmas.

For this project I was still able to use Snips, but since they are now part of Sonos, they are going to close their console. Next time I will be probably using snowboy and mycroft.

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๐Ÿ“… Nov 9, 2019  Hackster.io   micropython   esp8266   nodejs   chartjs
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