Arduino/build/shared/examples/10.StarterKit_BasicKit/p07_Keyboard/p07_Keyboard.ino

/*
  Arduino Starter Kit example
 Project 7  - Keyboard

 This sketch is written to accompany Project 7 in the
 Arduino Starter Kit

 Parts required:
 two 10 kilohm resistors
 1 Megohm resistor
 220 ohm resistor
 4 pushbuttons
 piezo

 Created 13 September 2012
 by Scott Fitzgerald

 http://www.arduino.cc/starterKit

 This example code is part of the public domain
*/

// create an array of notes
// the numbers below correspond to
// the frequencies of middle C, D, E, and F
int notes[] = {262, 294, 330, 349};

void setup() {
  //start serial communication
  Serial.begin(9600);
}

void loop() {
  // create a local variable to hold the input on pin A0
  int keyVal = analogRead(A0);
  // send the value from A0 to the Serial Monitor
  Serial.println(keyVal);

  // play the note corresponding to each value on A0
  if (keyVal == 1023) {
    // play the first frequency in the array on pin 8
    tone(8, notes[0]);
  } else if (keyVal >= 990 && keyVal <= 1010) {
    // play the second frequency in the array on pin 8
    tone(8, notes[1]);
  } else if (keyVal >= 505 && keyVal <= 515) {
    // play the third frequency in the array on pin 8
    tone(8, notes[2]);
  } else if (keyVal >= 5 && keyVal <= 10) {
    // play the fourth frequency in the array on pin 8
    tone(8, notes[3]);
  } else {
    // if the value is out of range, play no tone
    noTone(8);
  }
}