/*
  Pitch follower
 
 Emette un suono in base all'inuput di una fotoresistenza.
 Con autocalibrazione e limite minimo di attivazione


 circuit:
 * 8-ohm speaker on digital pin 8
 * photoresistor on analog 0 to 5V
 * 4.7K resistor on analog 0 to ground
 
 created 21 Jan 2010
 modified 31 May 2012
 by Tom Igoe, with suggestion from Michael Flynn
 2015 by eaman

This example code is in the public domain.

- http://www.dummies.com/how-to/content/how-to-make-an-instrument-with-the-arduino.html
- https://www.arduino.cc/en/Tutorial/tonePitchFollower
 
 */


// These constants won't change:
const int sensorPin = A0;    // pin that the sensor is attached to
const int ledPin = 9;        // pin that the LED is attached to

// variables:
// Calibration
int sensorValue = 0;         // the sensor value
int sensorMin = 1023;        // minimum sensor value
int sensorMax = 0;           // maximum sensor value

// Runtime vars
int sensorReading ;          // Analog value
int thisPitch ;              // Note to play

void setup() {
  // initialize serial communications (for debugging only):
  Serial.begin(9600);
    pinMode(13, OUTPUT);
  digitalWrite(13, HIGH);

  // calibrate during the first five seconds 
  while (millis() < 5000) {
    sensorValue = analogRead(sensorPin);

    // record the maximum sensor value
    if (sensorValue > sensorMax) {
      sensorMax = sensorValue;
    }

    // record the minimum sensor value
    if (sensorValue < sensorMin) {
      sensorMin = sensorValue;
    }
  }

  // signal the end of the calibration period
  digitalWrite(13, LOW);
}

void loop() {
  // read the sensor:
  sensorReading = analogRead(sensorPin);
  // print the sensor reading so you know its range
  Serial.println(sensorReading);
  // map the analog input range (in this case, 400 - 1000 from the photoresistor)
  // to the output pitch range (120 - 1500Hz)
  // change the minimum and maximum input numbers below
  // depending on the range your sensor's giving:
  thisPitch = map(sensorReading, sensorMin, sensorMax, 220, 3500);

  // play the pitch:
  if (sensorReading < sensorMax -50) {
  tone(ledPin, thisPitch, 10);
  }
  delay(1);        // delay in between reads for stability
}