//top sensor
#define trigPin 8
#define echoPin 9

//bottom sensor
#define trigPin2 10
#define echoPin2 11

//middle sensor
#define trigPin3 12
#define echoPin3 13


//#define speakerPin 6
#define speakerPin2 7


void setup() {
  
  Serial.begin (9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(trigPin2, OUTPUT);
  pinMode(echoPin2, INPUT);
  pinMode(trigPin3, OUTPUT);
  pinMode(echoPin3, INPUT);
  //pinMode(speakerPin, OUTPUT);
  pinMode(speakerPin2, OUTPUT);
 }

void loop() {

  //top sensor
  
  int duration, distance;
  digitalWrite (trigPin, HIGH);
  delayMicroseconds (10);
  digitalWrite (trigPin, LOW);
  duration = pulseIn (echoPin, HIGH);
  distance = (duration/2) / 29.1;
      
      
    if( distance < 10 ){

      tone (6, 1500, 500);
      Serial.print(distance);   
      Serial.print("mm");
      Serial.println();
  
  }
  
  //if nothing is close enough
  else { 
    //noTone(speakerPin);
    noTone(speakerPin2);
  }

  //bottom sensor
  
    int duration2, distance2;
    digitalWrite (trigPin2, HIGH);
    delayMicroseconds (10);
    digitalWrite (trigPin2, LOW);
    duration2 = pulseIn (echoPin2, HIGH);
    distance2 = (duration2/2) / 29.1;

    
    //sensor distance limit  
    if(distance2 < 10 ){

      tone (6, 2500, 500);
      Serial.print(distance2);   
      Serial.print("cm");
      Serial.println();
  }

  //if nothing is close enough
  else { 
    //noTone(speakerPin);
    noTone(speakerPin2);
  }

//middle sensor

    int duration3, distance3;
    digitalWrite (trigPin3, HIGH);
    delayMicroseconds (10);
    digitalWrite (trigPin3, LOW);
    duration3 = pulseIn (echoPin3, HIGH);
    distance3 = (duration3/2) / 29.1;
      
      
     if( distance3 < 10 ){

      tone (6, 4500, 500);
      Serial.print(distance3);   
      Serial.print("cm");
      Serial.println();
  
  }

  //if nothing is close enough
  else { 
    //noTone(speakerPin);
    noTone(speakerPin2);
  }

  }