#define BUZZER_PIN 15
#define SWITCH_PIN 4

bool isPlaying = false;

// 音階
#define NOTE_C4  262
#define NOTE_D4  294
#define NOTE_E4  330
#define NOTE_F4  349
#define NOTE_G4  392
#define NOTE_A4  440

int melody[] = {
  NOTE_C4, NOTE_C4, NOTE_G4, NOTE_G4, NOTE_A4, NOTE_A4, NOTE_G4,
  NOTE_F4, NOTE_F4, NOTE_E4, NOTE_E4, NOTE_D4, NOTE_D4, NOTE_C4
};

int noteDurations[] = {
  400, 400, 400, 400, 400, 400, 800,
  400, 400, 400, 400, 400, 400, 800
};

int notes = sizeof(melody) / sizeof(melody[0]);

void playMelody() {
  isPlaying = true;

  for (int i = 0; i < notes; i++) {
    tone(BUZZER_PIN, melody[i]);     // 周波数指定
    delay(noteDurations[i]);         // 再生時間

    noTone(BUZZER_PIN);              // 停止
    delay(50);                       // 音の間
  }

  isPlaying = false;
}

void setup() {
  pinMode(SWITCH_PIN, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);
}

void loop() {
  if (digitalRead(SWITCH_PIN) == LOW) {

    if (!isPlaying) {
      playMelody();
    }

    // チャタリング＆押しっぱなし対策
    delay(20);
    while (digitalRead(SWITCH_PIN) == LOW) {
      delay(10);
    }
  }
}