#define TRIG_PIN 3   
#define ECHO_PIN 2  
#define BUZZER_PIN 7 

void setup() {
  Serial.begin(9600);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);
}

void loop() {
  long duration, distance;
  
  
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  
  
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  

  duration = pulseIn(ECHO_PIN, HIGH);
  
 
  distance = duration * 0.034 / 2;
  
 
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" m");
  
  if (distance < 300) {
    digitalWrite(BUZZER_PIN, HIGH);
  } else {
    digitalWrite(BUZZER_PIN, LOW);
  }
  
  delay(1500); 
}