Laser Detector module

Want to set up your own laser tripwire? These little modules make it super simple. Just hook one up to your Arduino, line it up with a laser pointer, and you’ve got a working laser detection system. Add a buzzer or LED and it’ll trigger the moment someone breaks the beam. Perfect for security projects, spy gadgets, or just a fun electronics experiment.


Here is some quick code to get you up and running.  Shine a laser at the Sensor

Add power to 5V to VCC, Ground to GND and plug your middle pin into D2

Add a Buzzer on D8 and GND



// --- Pins ---
const int RX_DO_PIN   = 2;   // Receiver DO -> D2
const int LED_PIN     = 13;  // On-board LED for feedback
const int BUZZER_PIN  = 8;   // Active buzzer -> D8

// --- Tuning ---
const unsigned long STABLE_MS = 40;  // require this much stable time to accept change
const unsigned long POLL_MS   = 2;   // sampling interval

// Set this to true if your module needs a pull-up (some boards are open-collector)
const bool USE_INPUT_PULLUP = true;

void setup() {
  if (USE_INPUT_PULLUP) {
    pinMode(RX_DO_PIN, INPUT_PULLUP);
  } else {
    pinMode(RX_DO_PIN, INPUT);
  }
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);   // buzzer off
  Serial.begin(115200);
}

// Helper to read "laser seen?" abstracting the optional inversion
bool rawLaserSeen() {
  int v = digitalRead(RX_DO_PIN);
  if (USE_INPUT_PULLUP) {
    return (v == LOW);   // LOW means detected when pull-up is used
  } else {
    return (v == HIGH);  // HIGH means detected on actively-driven outputs
  }
}

void loop() {
  static bool stableState = false;     // debounced belief
  static bool lastSample  = false;     // last raw sample
  static unsigned long lastChangeMs = 0;

  bool sample = rawLaserSeen();

  if (sample != lastSample) {
    lastSample = sample;
    lastChangeMs = millis();           // raw level changed; restart stability timer
  }

  if ((millis() - lastChangeMs) >= STABLE_MS && sample != stableState) {
    stableState = sample;

    if (stableState) {
      Serial.println("Laser detected");
      digitalWrite(LED_PIN, HIGH);
      digitalWrite(BUZZER_PIN, LOW);   // <<< turn buzzer on
    } else {
      Serial.println("No laser");
      digitalWrite(LED_PIN, LOW);
      digitalWrite(BUZZER_PIN, HIGH);    // <<< turn buzzer off
    }
  }

  delay(POLL_MS);
}