IR Obstacle Sensor
Setup Guide

The IR sensor has two key components on its front face: an IR LED transmitter (emits infrared light continuously) and a photodiode receiver (listens for reflected light). When an object is in range, the IR light bounces back and the receiver detects it — the onboard LM393 comparator then pulls the OUT pin LOW to signal detection.

The OUT pin is LOW (0) when an obstacle is detected and HIGH (1) when the path is clear. The sketch below reads this pin and prints the status — and also blinks the built-in LED on pin 13 as a visual indicator.

// IR Obstacle Sensor — Basic Detection Sketch
// OUT pin → Arduino Pin 7

const int IR_OUT_PIN = 7;
const int LED_PIN    = 13;   // Built-in LED
bool lastState = HIGH;

void setup() {
  pinMode(IR_OUT_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
  Serial.begin(9600);
  Serial.println("IR Obstacle Sensor Ready");
}

void loop() {
  bool val = digitalRead(IR_OUT_PIN);

  if (val == LOW) {           // LOW = obstacle detected
    digitalWrite(LED_PIN, HIGH);
    if (lastState != LOW)
      Serial.println("OBSTACLE DETECTED");
  } else {                       // HIGH = clear
    digitalWrite(LED_PIN, LOW);
    if (lastState != HIGH)
      Serial.println("Path clear");
  }

  lastState = val;
  delay(50);
}

The blue potentiometer (the small knob with a cross-slot) controls how sensitive the sensor is — which effectively sets how far away it can detect objects.

Download the complete sample sketch — it includes wiring comments, state-change detection (prints only on change, not every loop), built-in LED feedback, and Serial Monitor output. No libraries needed.