// Declare variables
unsigned long duration;// variable that stores a positive value
int DT=500;
int distance;
int sensordist; 
const int trigPin = 10;
const int echoPin = 9;
void setup() {
  pinMode(trigPin,OUTPUT); //remember all pins are input unless specified otherwise
  pinMode(echoPin,INPUT);
  pinMode (8,OUTPUT); // buzzer
  analogRead (A2); // research pull up resistor
  Serial.begin(9600);  // Starts the serial communication
}
void loop () {
  digitalWrite(trigPin,LOW); // clear the pin
  delayMicroseconds(2);  // send out pulse
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(12);
  digitalWrite(trigPin, LOW);// listen for reflected sig.
  duration = pulseIn(echoPin, HIGH);// calculate distance
  distance = duration*0.0344/2; //this is in mm, travels to and from target ( hence ÷ 2)
 //display to screen
  Serial.print("distance = ");
  Serial.print(distance);
  Serial.println(" mm");
  delay (100);//delay}
 // determines when to play song 
  sensordist=analogRead(A2)/4;
  if (distance<sensordist){
    song();
  }
    else{
      delay(DT);
    }
  }
void song(){
  int beat=50;
  float semibreve=4*60000/beat;
  float minim=2*60000/beat;
  float crotchet=60000/beat;
  float dottedcrotchet=1.5*crotchet;
  float dottedminim=1.5*minim;
  float quaver=crotchet/2;
  float semiquaver=crotchet/4;
  float dottedquaver=quaver*1.5;
  float triplet=crotchet/3;
  // insert code here///
  tone (8,294,crotchet); delay(crotchet);//low D
  tone (8,587,crotchet); delay(crotchet);//  D
  }