#define ECHO_PIN 6
#define TRIG_PIN 7
#define relay 8

void setup() {
  pinMode(relay, OUTPUT);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  Serial.begin(9600); // Initialize serial communication
}

float readDistance() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  int duration = pulseIn(ECHO_PIN, HIGH);
  return duration * 0.034 / 2;
}

void loop() {
  float distance = readDistance();
  bool isNearby = (distance < 20);

  if (isNearby) {
    digitalWrite(relay, LOW); // Turn the water pump ON
  } else {
    digitalWrite(relay, HIGH); // Turn the water pump OFF
  }

  Serial.print("Measured distance: ");
  Serial.println(distance);

  delay(100);
}