#define trig 7 
#define echo 6 
#define led 13 
#define buzzer 12

long duration =0.0 ; 
int distance = 0 ;

void setup() {
  pinMode(trig, OUTPUT); 
  pinMode(echo, INPUT); 
  pinMode(led, OUTPUT); 
  pinMode(buzzer, OUTPUT); 
  Serial.begin(9600);


}

void loop() {
  digitalWrite(trig, LOW);
  delayMicroseconds(2);
  digitalWrite(trig, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig, LOW);
  
  long duration = pulseIn(echo, HIGH);
  
  distance= duration / 58;
  //distance= duration*0.034/2;

  if (distance > 300) {
    digitalWrite(led, HIGH); 
    noTone(buzzer);     // Stop sound...

  } else if (distance > 200) {
    noTone(buzzer);     // Stop sound...
   
    digitalWrite(led, HIGH);
    delay(500);
    digitalWrite(led, LOW);
    delay(500);


  } else {
    tone(buzzer, 100 ,1000); // Send 100Hz sound signal...
    
    digitalWrite(led, HIGH);
    delay(300);
    digitalWrite(led, LOW);
    delay(300);
        
  } 
   Serial.print("Distance in CM: ");
   Serial.println(distance);


}