IR remote light switch

Control your project like a TV. Each button on the infrared remote sends its own invisible code. In this project the UNO learns your remote's codes and uses buttons 1, 2 and 3 to switch a red, a yellow and a green LED, plus one button to turn everything off.

What you need

• UNO R3 board and USB cable
• IR remote control and IR receiver module
• Red, yellow and green LEDs
• 3 resistors, 220 Ω
• Breadboard and jumper wires (all from the UNO R3 Starter Kit)

Wiring

Check the labels printed on your IR module. Some modules order the pins differently.

Build it step by step

1. Install the IRremote library (by shirriff, z3t0 and ArminJo, version 4 or newer).
2. Wire the IR module and the three LEDs as in the diagram.
3. Upload the code and open the Serial Monitor at 9600 baud.
4. Point the remote at the receiver and press 1, 2, 3 and the button you want for "all off". Note the code shown for each one.
5. Put your codes into BTN_RED, BTN_YELLOW, BTN_GREEN and BTN_OFF, then upload again.
6. Press the buttons to switch the lights.

The code

#include <IRremote.hpp>

const int IR_PIN = 2;
const int RED_LED = 4;
const int YELLOW_LED = 5;
const int GREEN_LED = 6;

// Replace these with the codes your remote shows in the Serial Monitor
const uint8_t BTN_RED = 0x0C;
const uint8_t BTN_YELLOW = 0x18;
const uint8_t BTN_GREEN = 0x5E;
const uint8_t BTN_OFF = 0x16;

void toggle(int pin) {
  digitalWrite(pin, !digitalRead(pin));
}

void setup() {
  Serial.begin(9600);
  IrReceiver.begin(IR_PIN, ENABLE_LED_FEEDBACK);
  pinMode(RED_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
  Serial.println("Press a button on the remote");
}

void loop() {
  if (!IrReceiver.decode()) return;

  uint8_t command = IrReceiver.decodedIRData.command;
  bool isRepeat = IrReceiver.decodedIRData.flags & IRDATA_FLAGS_IS_REPEAT;
  IrReceiver.resume(); // ready for the next code

  if (isRepeat) return; // ignore the repeat signal while a button is held

  Serial.print("Button code: 0x");
  Serial.println(command, HEX);

  if (command == BTN_RED) toggle(RED_LED);
  else if (command == BTN_YELLOW) toggle(YELLOW_LED);
  else if (command == BTN_GREEN) toggle(GREEN_LED);
  else if (command == BTN_OFF) {
    digitalWrite(RED_LED, LOW);
    digitalWrite(YELLOW_LED, LOW);
    digitalWrite(GREEN_LED, LOW);
  }
}

How it works

The remote flashes an infrared LED in a fast pattern that our eyes can't see. The receiver module turns that light into pulses on its signal pin, and the IRremote library decodes the pulses into a command number for each button. toggle() reads the LED's current state and sets the opposite, so the same button switches it on and off. Holding a button sends "repeat" signals, which the sketch ignores.

Make it your own

• Use the arrow buttons to dim an LED up and down with analogWrite() on a PWM pin.
• Control the RGB LED and give each button its own colour.
• Combine this with the servo lesson to move a servo from the remote.

Troubleshooting

• No codes appear: check the S wire on pin 2, and make sure nothing blocks the receiver.
• Different codes every time: point the remote straight at the receiver, from about 1 m.
• Compile errors: make sure IRremote version 4 or newer is installed.

Learn the basics first

New to these parts? These lessons explain them step by step: Set up the Arduino IDE and blink an LED and Make a tilt alarm with a buzzer.