Pitch follower by Tom Igoe

Plays a pitch that changes based on a changing analog input circuit: 8-ohm speaker on digital pin 8 photoresistor on analog 0 to 5V 4.7K resistor on analog 0 to ground

void setup()
{
  // initialize serial communications (for debugging only):
  Serial.begin(9600);
}

void loop()
{
  // read the sensor:
  int sensorReading = analogRead(A0);
  // print the sensor reading so you know its range
  Serial.println(sensorReading);
  // map the pitch to the range of the analog input.
  // change the minimum and maximum input numbers below
  // depending on the range your sensor's giving:
  int thisPitch = map(sensorReading, 400, 1000, 100, 1000);

  // play the pitch:
  tone(8, thisPitch, 10);
}