#define RELAY_PIN 2
// Define ultrasonic sensor pins
#define TRIGGER_PIN 3
#define ECHO_PIN 4
// Variables for ultrasonic sensor
long duration;
int distance;

void setup() {
  // Initialize the relay pin as an output
  pinMode(RELAY_PIN, OUTPUT);

  // Initialize the ultrasonic sensor pins
  pinMode(TRIGGER_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  // Start serial communication
  Serial.begin(9600);
}

void loop() {
  // Trigger ultrasonic sensor
  digitalWrite(TRIGGER_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIGGER_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGGER_PIN, LOW);
  // Measure the duration of the pulse
  duration = pulseIn(ECHO_PIN, HIGH);
  // Calculate distance in cm
  distance = duration * 0.034 / 2;
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Check if distance is greater than 5 cm
  if (distance > 5) {
    // Turn on the relay
    digitalWrite(RELAY_PIN, HIGH);
    Serial.println("Relay turned ON");
  } else {
    // Turn off the relay
    digitalWrite(RELAY_PIN, LOW);
    Serial.println("Relay turned OFF");
  }

  // Wait for a short delay before next measurement
  delay(1000); // Adjust this delay as needed
}