Step 1: Overview

This project demonstrates how to use an ESP32 with an LDR (Light Dependent Resistor) module, a laser module, and a buzzer to create a simple security system. The system detects changes in light intensity using the LDR and triggers an alarm when the light beam is interrupted.

Step 2: Components Required

• ⁠ ⁠ESP32 Development Board
  •⁠ ⁠LDR Module (Light Dependent Resistor)
  •⁠ ⁠Laser Module
  •⁠ ⁠Buzzer or LED
  •⁠ ⁠Breadboard & Jumper Wires
  •⁠ ⁠Mirrors (optional for creating a laser mesh)

Step 3: Circuit Connections

Connecting the LDR Module to ESP32

• ⁠ ⁠VCC of LDR Module → 3.3V of ESP32
  •⁠ ⁠GND of LDR Module → GND of ESP32
  •⁠ ⁠DO(Output) of LDR Module → GPIO 13 of ESP32

Connecting the Buzzer/LED to ESP32

• ⁠ ⁠Buzzer/LED Pin → GPIO 18 of ESP32
  •⁠ ⁠GND of Buzzer/LED → GND of ESP32

Connecting the Laser Module to ESP32

• ⁠ ⁠S (Signal) → GPIO 4 of ESP32
  •⁠ ⁠VCC → 5V of ESP32
  •⁠ ⁠GND → GND of ESP32

Step 4: Breadboard Wiring Guide

1. ⁠ ⁠Place the ESP32 on the breadboard.
   2.⁠ ⁠Connect the LDR module’s VCC to the ESP32’s 3.3V, and GND to ESP32’s GND.
   3.⁠ ⁠Connect the DO pin of the LDR module to GPIO 22 and the AO pin to GPIO 13 of ESP32.
   4.⁠ ⁠Connect the buzzer’s positive pin to GPIO 18, and its negative pin to GND.
   5.⁠ ⁠Connect the laser module’s S (Signal) pin to GPIO 4, VCC to 3.3V, and GND to ESP32’s GND.
   6.⁠ ⁠Ensure all components are securely connected.

Step 5: Upload ESP32 Code

Copy and paste the following code into your Arduino IDE and upload it to your ESP32:

const int ldrPin = 13;   // Analog input pin for LDR
const int buzzerPin = 18; // Buzzer pin
const int laser = 4;      // GPIO pin for laser module

void setup() {
  pinMode(ldrPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(laser, OUTPUT);
  digitalWrite(laser, HIGH);  // Keep the laser on
  Serial.begin(115200);
}

void playAlarm() {
  int melody[] = {1000, 1200, 1500, 1200}; // Frequency pattern
  int duration[] = {200, 200, 300, 200};   // Duration pattern
  
  for (int i = 0; i < 4; i++) {
    tone(buzzerPin, melody[i]);
    delay(duration[i]);
    noTone(buzzerPin);
    delay(100);
  }
}

void loop() {
  int analogValue = analogRead(ldrPin); // Read light intensity
  Serial.print(" | Analog Value: ");
  Serial.println(analogValue);

  // Trigger alarm if light beam is broken
  if (analogValue > 3500) { 
    playAlarm();
  }
  delay(100);
}

Step 6: How It Works

1. ⁠ ⁠The laser continuously shines on the LDR sensor.
   2.⁠ ⁠When an object interrupts the laser beam, the light reaching the LDR decreases.
   3.⁠ ⁠The ESP32 detects this change and triggers the buzzer alarm.
   4.⁠ ⁠You can modify the threshold value (3500 in code) to suit different lighting conditions.

Step 7: Testing and Enhancements

• ⁠ ⁠Test in a dark environment for better sensitivity.
  •⁠ ⁠Use mirrors to create a laser mesh for added security.
  •⁠ ⁠Add an IoT feature by sending notifications when the alarm triggers.
  •⁠ ⁠Use a relay to activate higher-power sirens or lights.

Step 8: Conclusion

This simple ESP32-based security system demonstrates how LDR and laser modules can be used to detect intrusions. By expanding the setup with mirrors and multiple sensors, you can create a robust security system.