Interfacing Infrared LED with Arduino

Infrared LED (IR Transmitter)

An Infrared (IR) LED emits light in the infrared spectrum, which is invisible to the human eye but can be detected by IR receivers. These LEDs are commonly used in remote controls, obstacle sensors, and communication systems with Arduino.

Working Principle of IR LED

The IR LED works like a regular LED but emits light in the 850–950 nm range. When powered through an Arduino, it sends modulated infrared signals that can be detected by a matching IR receiver module. The modulation (typically 38kHz) allows the signal to stand out from ambient light.

Types of Infrared LEDs

Standard IR LED

  • Used in basic communication and obstacle sensors.
  • Requires manual modulation or pulse control in code.
  • Simple and cost-effective for basic IR tasks.

IR LED with Modulator

  • Used in remote control systems.
  • Pairs well with IR receivers tuned to 38kHz.
  • Offers better signal clarity in ambient light.

Requirements

1. Arduino (Uno, Nano, etc.)

2. Infrared LED

3. 220Ω Resistor

4. Jumper Wires and Breadboard

Pin Configuration of IR LED Circuit

Basic IR LED Wiring

  • Anode (long leg): Connect to Arduino digital pin via 220Ω resistor.
  • Cathode (short leg): Connect to GND on Arduino.
  • Use a current-limiting resistor to avoid damage.
  • Optionally add a transistor for switching higher current.

Wiring the IR LED to Arduino

Connect the anode of the IR LED to a digital pin on the Arduino through a resistor (typically 220Ω). The cathode goes to ground. To send modulated signals, include the IRremote library and use `IRsend` functions to transmit codes.

Algorithm

  1. Connect the IR LED

    • Wire the IR LED's anode to Arduino pin (e.g., D3) through a resistor.
    • Connect the cathode to ground.
    • Use a transistor if higher current is required.

  2. Include Necessary Libraries

    • Install and include the IRremote library.
    • Define the IR send pin using `IRsend irsend;`.
    • Enable IR transmission in `setup()`.

  3. Transmit Infrared Signals

    • Use `irsend.sendNEC(0xF7C03F, 32);` to send an IR code.
    • Repeat signals in `loop()` or based on user input (e.g., button press).
    • Adjust timing or codes as needed for your device.

  4. Test the IR Output

    • Use a smartphone camera to see if the IR LED flashes (as humans can't see IR).
    • Use an IR receiver module to verify communication.
    • Troubleshoot wiring or timing if no signal is received.
1#define IR_LED 7   // Pin connected to IR LED via resistor
2
3void setup() {
4  pinMode(IR_LED, OUTPUT);
5}
6
7void loop() {
8  digitalWrite(IR_LED, HIGH);  // Emit IR signal
9  delay(1000);
10  digitalWrite(IR_LED, LOW);   // Stop IR emission
11  delay(1000);
12}
13

Applications of Infrared LED with Arduino

  • TV and appliance remote controls
  • IR obstacle avoidance sensors
  • Wireless data transmission
  • Line-following robots
  • Home automation IR blasters
  • Object counters using IR beam break

Conclusion

Using an Infrared LED with Arduino opens up a variety of wireless communication possibilities. Whether you're building a custom remote or a robot that senses obstacles, IR LEDs are a simple yet powerful tool in your electronics toolkit.