Interfacing an IR Sensor with ROS 2

Connection diagram

IR sensor pin	NodeMCU pin
VCC	5V
GND	GND
OUT	18

Check the board and sensor before wiring. The original notes mix NodeMCU/ESP8266 pin names with an ESP32 GPIO 18 example, and list both 3.3V and 5V power. Use the pin map and voltage supported by your exact board and sensor.

Arduino code for IR (test code, without ROS)

This sketch reads an IR obstacle sensor, debounces changes, controls the built-in LED, and reports state changes over Serial.

/*
To use this code, wire your IR obstacle sensor to the ESP8266.
- VCC on the IR sensor goes to 3V3 (or Vin/5V if your sensor is 5V tolerant) on the ESP8266.
- GND on the IR sensor goes to GND on the ESP8266.
- OUT (Data) on the IR sensor goes to D5 (GPIO14) on the ESP8266.

If your sensor is Active-HIGH (outputs HIGH when an obstacle is detected), change:
#define ACTIVE_LOW false
*/

// Simple ESP32 IR Obstacle Sensor Code
#define LED_PIN 2           // Built-in LED on most ESP32 boards
#define IR_SENSOR_PIN 18    // IR sensor OUT pin connected to GPIO18

// Change this based on your sensor:
// true = sensor outputs LOW when obstacle detected (most common)
// false = sensor outputs HIGH when obstacle detected
#define ACTIVE_LOW true

bool lastSensorState = HIGH;
unsigned long lastDebounceTime = 0;
const unsigned long debounceDelay = 50;

void setup() {
    Serial.begin(115200);
    delay(1000);
    Serial.println("ESP32 IR Sensor - Serial Working");

    pinMode(IR_SENSOR_PIN, INPUT);
    pinMode(LED_PIN, OUTPUT);
    digitalWrite(LED_PIN, LOW);

    Serial.println("IR Sensor initialized on GPIO" + String(IR_SENSOR_PIN));
    Serial.println("Active LOW: " + String(ACTIVE_LOW ? "Yes" : "No"));
    Serial.println("Ready!");
}

void loop() {
    int sensorReading = digitalRead(IR_SENSOR_PIN);
    bool obstacleDetected = ACTIVE_LOW ? sensorReading == LOW : sensorReading == HIGH;

    if (sensorReading != lastSensorState) {
        lastDebounceTime = millis();
    }

    if ((millis() - lastDebounceTime) > debounceDelay) {
        digitalWrite(LED_PIN, obstacleDetected ? HIGH : LOW);

        static bool lastObstacleState = false;
        if (obstacleDetected != lastObstacleState) {
            Serial.println(obstacleDetected ? "🚨 OBSTACLE DETECTED!" : "✓ Path clear");
            lastObstacleState = obstacleDetected;
        }
    }

    lastSensorState = sensorReading;
    delay(10);
}

Connection diagram

Arduino code for IR (test code, without ROS)

References