/* ---------------------------------------------------------------------------
 Simple Helmet sonar pathfinder..
5/16/2016
 */
   
    int echoPin =  11;
    int trigPin =  12;
    int soundPin = 10; // Piezo
    long duration, distance;

    void setup() {
    pinMode(trigPin, OUTPUT);
    pinMode(echoPin, INPUT);
       }

    void loop() {
 
    digitalWrite(trigPin, LOW);
    delayMicroseconds(2);

    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);

    digitalWrite(trigPin, LOW);
    duration = pulseIn(echoPin, HIGH);

    //Calculate the distance (in cm) based on the speed of sound.
    distance = duration/58.2;

    tone(soundPin, 800, 300);
    delay(distance); // Distance is the delay in ms between tones, ie Near maxRange -> Long tones, Near minimumRange -> Rapid tones.
    noTone(soundPin);

    // Mandatory delay
    delay(50);
    }