IR Sensor Example

This example walks through how to control an IR Sensor using an Arduino board. Your project kit has an IR Sensor. IR Sensors are used to detect the presence of an object. They work by emitting an infrared light and measuring the amount of light that is reflected back. In this example, we will learn how to control an IR Sensor using an Arduino board.

See also

For more information on the IR Sensor, see the YouTube tutorial on Using an IR Sensor with the Arduino , a guide developed specifically for USF students.

/**
 * How to Read from an IR Sensor using an Arduino
 * ---------------------------------------------
 * Foundations of Engineering Lab
 * The University of South Florida
 * Created by Trevor Flahardy on 1/18/2025
 * ---------------------------------------------
 * An IR sensor is a type of sensor that detects objects by
 * emitting and receiving infrared light. In this example, we
 * will learn how to read from an IR sensor using an Arduino board.
 *
 * The IR sensor in your project kit is a digital sensor, which means
 * it will return a value of either HIGH or LOW. The IR sensor will
 * return a HIGH value when it is detecting an object, and a LOW value
 * when it is not detecting an object.
 *
 * The IR sensor is connected to pin 9, and the onboard LED is connected
 * to pin 13. When the IR sensor detects an object, the LED will turn OFF.
 * When the IR sensor does not detect an object, the LED will turn ON.
 */

const int IR_SENSOR_PIN = 9; // The IR sensor is connected to pin 9

void setup()
{
    Serial.begin(9600); // Start the Serial Monitor at 9600 baud

    // The IR sensor pin is being read from, so we need to
    // set it as an INPUT.
    pinMode(IR_SENSOR_PIN, INPUT);

    // The LED will be sent 5V when we detect an object
    // with the IR sensor, so we need to set it as an OUTPUT.
    pinMode(LED_BUILTIN, OUTPUT);
}

void loop()
{
    // Read from the IR_SENSOR_PIN. When this value is HIGH,
    // it means that the IR sensor is detecting an object.
    int ir_sensor_value = digitalRead(IR_SENSOR_PIN);

    if (ir_sensor_value == HIGH)
    {
        // This IR sensor is detecting an object. Turn OFF the LED
        // because the object is too close.
        digitalWrite(LED_BUILTIN, LOW);

        // Print a message to the Serial Monitor.
        Serial.println("Object detected! LED OFF.");
    }
    else
    {
        // This IR sensor is not detecting an object. Turn ON the LED
        // because the object is too far away.
        digitalWrite(LED_BUILTIN, HIGH);

        // Print a message to the Serial Monitor.
        Serial.println("No object detected! LED ON.");
    }
}

This is a whole code block. It can be used by itself.