IR Receiver and Remote Control: Remote-Controlled Projects with Arduino

Remote controls for TVs, air conditioners and stereos work with infrared (IR) light. Add an IR receiver that costs next to nothing to an Arduino and you can read the buttons of almost any remote in your home and use them to control lamps, LEDs, motors or music. No pairing, app or internet needed; you just point the remote at the board and press a button. It's the easiest and cheapest route to your first remote-controlled project.

How does an infrared remote work?

The IR LED at the tip of the remote emits light at about 940 nm, which the eye can't see. The light isn't on constantly; it rides on a carrier signal that flashes 38,000 times a second. The circuit inside the receiver only pays attention to light flickering at that frequency, so sunlight and lamps can't disturb the signal. The receiver turns the flicker into clean digital pulses and pulls its output LOW while the signal is present.

Which button was pressed is encoded in the lengths of the pulses and the gaps between them. There are different "languages" for this, called protocols: the most common is NEC (an address byte and a command byte), and Sony, RC5 (Philips) and Samsung protocols are also common. Luckily the library does the decoding; you just read the button's code.

Specifications (VS1838B)

IR receiver wiring

Reading button codes with the IRremote library

In the Library Manager, search for IRremote and install the library by Armin Joachimsmeyer. The code below works with version 4.x; every time you press a button it prints the protocol, address and command code to the Serial Monitor. If you see commands such as IRrecv and decode(&results) in older examples online, they belong to an old version.

1#include <IRremote.hpp>
2
3const int IR_PIN = 2;
4
5void setup() {
6  Serial.begin(9600);
7  IrReceiver.begin(IR_PIN, ENABLE_LED_FEEDBACK);   // sinyal gelince dahili LED yanar / onboard LED blinks on signal
8}
9
10void loop() {
11  if (IrReceiver.decode()) {
12    Serial.print("Komut / command: 0x");
13    Serial.println(IrReceiver.decodedIRData.command, HEX);
14    IrReceiver.printIRResultShort(&Serial);        // protokol ve adres / protocol and address
15    IrReceiver.resume();                           // sonraki tuşa hazırlan / ready for the next key
16  }
17}

Press the buttons on your remote one by one and note the codes. The small 21-key remotes included in kits usually use the NEC protocol, and their codes are mostly as shown below; still, confirm them by reading your own remote's codes:

Controlling an LED and a relay with a remote

Once you know the codes, you can give each button a job. In the example below, the "1" button toggles a relay, and VOL+ and VOL- set an LED's brightness with PWM. When a button is held down, the remote sends repeat signals; for on-off jobs you need to ignore these repeats, otherwise the relay flicks on and off. For relay wiring, see What Is a Relay Module?

1#include <IRremote.hpp>
2
3const int IR_PIN = 2;
4const int LED_PIN = 9;       // PWM pini / PWM pin
5const int RELAY_PIN = 7;     // aktif LOW röle / active-LOW relay
6
7bool relayOn = false;
8int brightness = 128;
9
10void setup() {
11  pinMode(LED_PIN, OUTPUT);
12  pinMode(RELAY_PIN, OUTPUT);
13  digitalWrite(RELAY_PIN, HIGH);
14  IrReceiver.begin(IR_PIN);
15}
16
17void loop() {
18  if (!IrReceiver.decode()) return;
19  bool repeat = IrReceiver.decodedIRData.flags & IRDATA_FLAGS_IS_REPEAT;   // tuş basılı tutuluyor / key held down
20  switch (IrReceiver.decodedIRData.command) {
21    case 0x0C:                               // "1": röleyi aç-kapa / toggle the relay
22      if (!repeat) {
23        relayOn = !relayOn;
24        digitalWrite(RELAY_PIN, relayOn ? LOW : HIGH);
25      }
26      break;
27    case 0x15:                               // VOL+: daha parlak / brighter
28      brightness = min(brightness + 15, 255);
29      break;
30    case 0x07:                               // VOL-: daha sönük / dimmer
31      brightness = max(brightness - 15, 0);
32      break;
33  }
34  analogWrite(LED_PIN, brightness);
35  IrReceiver.resume();                       // sonraki tuşa hazırlan / ready for the next key
36}

Sending IR signals with Arduino

An Arduino can do more than listen to remotes; it can be a remote itself. Connect an IR LED (940 nm) to pin 3 of the Uno through a 100 Ω resistor; to increase the range, you can drive the LED through a transistor. First read the remote of the device you want to control with the code above to learn its address and command, then send the same code from the Arduino:

1#include <IRremote.hpp>
2
3const int IR_SEND_PIN = 3;    // IR LED, 100 Ω direnç ile / IR LED with a 100 Ω resistor
4
5void setup() {
6  IrSender.begin(IR_SEND_PIN);
7}
8
9void loop() {
10  IrSender.sendNEC(0x00, 0x46, 0);   // adres, komut, tekrar sayısı / address, command, repeats
11  delay(5000);
12}

IR with the ESP32 and Raspberry Pi Pico

The VS1838B works fine at 3.3 V, so it connects directly to the ESP32 and Pico. The IRremote library supports the ESP32; you can connect the receiver to any input pin, such as GPIO 15. With an ESP32 you can forward remote button presses to other devices over Wi-Fi, or build a "smart remote" that sends commands from your phone to the TV with an IR LED. On the Pico with MicroPython, Peter Hinch's micropython_ir library is used:

1from machine import Pin
2from ir_rx.nec import NEC_8          # micropython_ir kütüphanesi / library (Peter Hinch)
3import time
4
5def on_key(command, address, ctrl):
6    if command >= 0:                 # negatif değerler tekrar ya da hata / negatives mean repeat or error
7        print("Komut / command: 0x{:02X}".format(command))
8
9ir = NEC_8(Pin(16, Pin.IN), on_key)  # GP16 → OUT
10
11while True:
12    time.sleep(1)

IR receiver and remote project ideas

• Remote-controlled lamp: switch a mains lamp on through a relay with a spare button on your TV remote.
• Colour remote: change the colour of an RGB LED with the number buttons.
• Remote-controlled robot car: a car whose two motors you steer with the arrow buttons.
• Melody box: assign a different tune to each number button; for the sound part see What Is a Buzzer?
• Learning remote: record the codes of other remotes and send them from a single Arduino.
• Code lock: open a lock with a servo when the right button sequence is entered.

Common mistakes and how to fix them

• No codes arrive at all: the OUT wire is on a different pin from the code, the receiver's legs are reversed, or the remote's battery is flat; check the remote with your phone camera.
• The example code won't compile: old examples online are for IRremote 2.x; version 4.x uses IrReceiver.begin() and IrReceiver.decode().
• Random codes appear: the receiver may be facing direct sunlight or a fluorescent lamp; move it into the shade.
• The on-off button works twice: repeat signals aren't being ignored; check the IRDATA_FLAGS_IS_REPEAT flag.
• tone() or PWM on pins 3 and 11 misbehaves: on the Uno they share the same timer (Timer2) as IRremote.
• Very short range when sending with an IR LED: drive the LED at a higher current through a transistor and point it at the device.

An IR receiver is the simplest and cheapest way to go wireless; even old remotes lying around the house get a second life in your new projects. In the BlueGrays app you'll find projects for reading remote codes, switching LEDs, playing melodies from a remote, controlling a mains lamp and building an ESP32 universal remote, with circuit diagrams and code.