#define echoPin 7 // Echo pin of the ultrasonic sensor
#define trigPin 6 // Trig pin of the ultrasonic sensor
#define pirPin 2  // PIR sensor pin
#define tempPin A0 // Thermistor pin

// Constants for temperature calculation
#define RT0 10000   // Thermistor resistance at 25°C
#define B 3977      // B coefficient of the thermistor
#define VCC 5      // Supply voltage
#define R 10000     // Series resistor value
#define T0 25       // Reference temperature in Celsius

// Variables
long duration; // Variable for the duration of sound wave travel
int distance; // Variable for the distance measurement
int pirValue = 0; // Variable to store PIR sensor value
float temperature; // Variable to store temperature

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(pirPin, INPUT);
  pinMode(tempPin, INPUT);

  Serial.begin(9600);
}

void loop() {
  // Read PIR sensor value
  pirValue = digitalRead(pirPin);
  
  // Read temperature
  temperature = readTemperature();
  
  // Read distance from ultrasonic sensor
  distance = readUltrasonic();

  // Logic to control LEDs based on specified conditions
  if (pirValue && temperature >= 20 && temperature <= 30 && distance >= 10 && distance <= 40) {
    // Turn on LED1
    // Code to turn on LED1
    Serial.println("LED1 ON");
  }

  if (pirValue && temperature >= 30 && temperature <= 40 && distance >= 40 && distance <= 100) {
    // Turn on LED2
    // Code to turn on LED2
    Serial.println("LED2 ON");
  }

  if (pirValue && temperature >= 30 && temperature <= 50 && distance >= 100 && distance <= 300) {
    // Turn on LED3
    // Code to turn on LED3
    Serial.println("LED3 ON");
  }

  delay(1000); // Delay for stability and to prevent rapid serial output
}

// Function to read temperature from thermistor
float readTemperature() {
  float VRT = analogRead(tempPin) * (VCC / 1024.0); // Convert analog reading to voltage
  float VR = VCC - VRT;
  float RT = VRT / (VR / R); // Calculate thermistor resistance
  float TX = 1 / ((log(RT / RT0) / B) + (1 / (T0 + 273.15))); // Calculate temperature in Kelvin
  return TX - 273.15; // Convert Kelvin to Celsius
}

// Function to read distance from ultrasonic sensor
int readUltrasonic() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  return duration * 0.034 / 2; // Convert duration to distance in cm
}