Wireless-controlled RGB LED

Can we control the color of a RGB LED without any wire?

BeginnerShowcase (no instructions)30 minutes3,560

Things used in this project

Hardware components

Arduino UNO

NRF24L01

Breadboard (generic)

Rotary potentiometer (generic)

USB-A to B Cable

Jumper wires (generic)

Software apps and online services

Arduino IDE

Story

In a few words:

Can we control the color of a RGB LED without any wire? It could be great if we could change the color from a remote device according to our mood or even our favorite football team (it’s EURO 2016, you know).

Now the detailed version

We are a group of 1st year students at CentraleSupélec Rennes. This work is part of a short-term project we must achieve using our knowledge in electronics, signal processing and so on. The final goal of the project is to make something similar to the really cool “Romance Pants” project https://vimeo.com/45152498

This is a funny IoT device.

We did not want to make a live demonstration to our professors

And well, it could be adapted for other applications.

Finally: in all cases, this is a wireless device! We’ll be able to reuse the driver of the wireless chip for any other project with such a feature.

There were several steps in our project. First, we had to play with Arduino boards as it was our first experience with it. Then, run an example with the wireless chips. In “Romance Pants”, there is a zipper which is a bit complicated to build. In a few words, this is only a potentiometer with some resistors attached to its pins:

If we close the zipper, the overall resistance is higher.

If we open it, it is lower.

Therefore, for our first demonstration, we replaced the zipper by a classic potentiometer. For the target device, we use a simple RGB LED. Why? Because it is easier to implement than volume controls as you can see in “Romance Pants”.

At the end of this tutorial, you’ll have a cool RGB LED which can be controlled 10m away at least!

Here is a video of our result:

Code

#include <nRF24L01.h>
#include <RF24.h>
#include <RF24_config.h>
#include <SPI.h>

/*
This sketch receives strings from sending unit via nrf24 
and prints them out via serial.  The sketch waits until
it receives a specific value (2 in this case), then it 
prints the complete message and clears the message buffer.
*/

int msg[1];
RF24 radio(9,10);
const uint64_t pipe = 0xE8E8F0F0E1LL;



int valPot=0; //variable qui va stocker la tension lue. On l'initialise  0.
int ledRouge=7;
int ledBleu=5;
int ledVert=3;// pin de connexion de la LED

void setup(){
  Serial.begin(9600);
  radio.begin();
  radio.openReadingPipe(1,pipe);
  radio.startListening();
  
  pinMode(ledRouge,OUTPUT);
  pinMode(ledBleu,OUTPUT); 
  pinMode(ledVert,OUTPUT); 
}
void loop(){
  if (radio.available()){
    radio.read(msg, sizeof(msg)); 
    Serial.println(msg[0]);
    valPot=msg[0];
    analogWrite(ledRouge,valPot);
    analogWrite(ledBleu,255-valPot);
    analogWrite(ledVert,130+valPot);
    delay(10);
  
  }
  else {
    //Serial.println("albiche\n");
  }
}

Credits

Alban Germain & Zahra Sekkat

Posted by

Pascal Cotret

Thanks to Alban Germain and Zahra Sekkat.

Wireless-controlled RGB LED