​#define  a3f 208     // 208 Hz
#define  b3f 233     // 233 Hz
#define  b3 247     // 247 Hz
#define  c4 261     // 261 Hz MIDDLE C
#define  c4s 277     // 277 Hz
#define  e4f 311     // 311 Hz
#define  f4 349     // 349 Hz
#define  a4f 415     // 415 Hz
#define  b4f 466     // 466 Hz
#define  b4 493     // 493 Hz
#define  c5 523     // 523 Hz
#define  c5s 554     // 554 Hz
#define  e5f 622     // 622 Hz
#define  f5 698     // 698 Hz
#define  f5s 740     // 740 Hz
#define  a5f 831     // 831 Hz

#define rest    -1

// change these pins according to your setup
int piezo = 3;
int led = 13;

volatile int beatlength = 100; // determines tempo
float beatseparationconstant = 0.3;

int a; // part index
int b; // song index
int c; // lyric index

boolean flag; // play/pause

// Parts 1 and 2 (Intro)

int song1_intro_melody[] =
{c5s, e5f, e5f, f5, a5f, f5s, f5, e5f, c5s, e5f, rest, a4f, a4f};

int song1_intro_rhythmn[] =
{6, 10, 6, 6, 1, 1, 1, 1, 6, 10, 4, 2, 10};

// Parts 3 or 5 (Verse 1)

int song1_verse1_melody[] =
{ rest, c4s, c4s, c4s, c4s, e4f, rest, c4, b3f, a3f,
rest, b3f, b3f, c4, c4s, a3f, a4f, a4f, e4f,
rest, b3f, b3f, c4, c4s, b3f, c4s, e4f, rest, c4, b3f, b3f, a3f,
rest, b3f, b3f, c4, c4s, a3f, a3f, e4f, e4f, e4f, f4, e4f,
c4s, e4f, f4, c4s, e4f, e4f, e4f, f4, e4f, a3f,
rest, b3f, c4, c4s, a3f, rest, e4f, f4, e4f
};

int song1_verse1_rhythmn[] =
{ 2, 1, 1, 1, 1, 2, 1, 1, 1, 5,
1, 1, 1, 1, 3, 1, 2, 1, 5,
1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 3,
1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 4,
5, 1, 1, 1, 1, 1, 1, 1, 2, 2,
2, 1, 1, 1, 3, 1, 1, 1, 3
};

char* lyrics_verse1[] =
{ "We're ", "no ", "strangers ", "", "to ", "love ", "", "\r\n",
"You ", "know ", "the ", "rules ", "and ", "so ", "do ", "I\r\n",
"A ", "full ", "commitment's ", "", "", "what ", "I'm ", "thinking ", "", "of", "\r\n",
"You ", "wouldn't ", "", "get ", "this ", "from ", "any ", "", "other ", "", "guy\r\n",
"I ", "just ", "wanna ", "", "tell ", "you ", "how ", "I'm ", "feeling", "\r\n",
"Gotta ", "", "make ", "you ", "understand", "", "\r\n"
};

// Parts 4 or 6 (Chorus)

int song1_chorus_melody[] =
{ b4f, b4f, a4f, a4f,
f5, f5, e5f, b4f, b4f, a4f, a4f, e5f, e5f, c5s, c5, b4f,
c5s, c5s, c5s, c5s,
c5s, e5f, c5, b4f, a4f, a4f, a4f, e5f, c5s,
b4f, b4f, a4f, a4f,
f5, f5, e5f, b4f, b4f, a4f, a4f, a5f, c5, c5s, c5, b4f,
c5s, c5s, c5s, c5s,
c5s, e5f, c5, b4f, a4f, rest, a4f, e5f, c5s, rest
};

int song1_chorus_rhythmn[] =
{ 1, 1, 1, 1,
3, 3, 6, 1, 1, 1, 1, 3, 3, 3, 1, 2,
1, 1, 1, 1,
3, 3, 3, 1, 2, 2, 2, 4, 8,
1, 1, 1, 1,
3, 3, 6, 1, 1, 1, 1, 3, 3, 3, 1, 2,
1, 1, 1, 1,
3, 3, 3, 1, 2, 2, 2, 4, 8, 4
};

char* lyrics_chorus[] =
{ "Never ", "", "gonna ", "", "give ", "you ", "up\r\n",
"Never ", "", "gonna ", "", "let ", "you ", "down", "", "\r\n",
"Never ", "", "gonna ", "", "run ", "around ", "", "", "", "and ", "desert ", "", "you\r\n",
"Never ", "", "gonna ", "", "make ", "you ", "cry\r\n",
"Never ", "", "gonna ", "", "say ", "goodbye ", "", "", "\r\n",
"Never ", "", "gonna ", "", "tell ", "a ", "lie ", "", "", "and ", "hurt ", "you\r\n"
};

void setup()
{
pinMode(piezo, OUTPUT);
pinMode(led, OUTPUT);
digitalWrite(led, LOW);
Serial.begin(9600);
flag = true;
a = 4;
b = 0;
c = 0;
}

void loop()
{
// edit code here to define play conditions
/*
  if (CONDITION 1) { // play
  flag = true;
  }
  else if (CONDITION2) { // pause
  flag = false;
  }
*/

// play next step in song
if (flag == true) {
  play();
}
}

void play() {
int notelength;
if (a == 1 || a == 2) { // Intro
  // intro
  notelength = beatlength * song1_intro_rhythmn[b];
  if (song1_intro_melody[b] > 0) { // if not a rest, play note
    digitalWrite(led, HIGH);
    tone(piezo, song1_intro_melody[b], notelength);
  }
  b++;
  if (b >= sizeof(song1_intro_melody) / sizeof(int)) {
    a++;
    b = 0;
    c = 0;
  }
}
else if (a == 3 || a == 5) { // Verse 1
  // verse
  notelength = beatlength * 2 * song1_verse1_rhythmn[b];
  if (song1_verse1_melody[b] > 0) {
    digitalWrite(led, HIGH);
    Serial.print(lyrics_verse1[c]);
    tone(piezo, song1_verse1_melody[b], notelength);
    c++;
  }
  b++;
  if (b >= sizeof(song1_verse1_melody) / sizeof(int)) {
    a++;
    b = 0;
    c = 0;
  }
}
else if (a == 4 || a == 6) { //chorus
  // chorus
  notelength = beatlength * song1_chorus_rhythmn[b];
  if (song1_chorus_melody[b] > 0) {
    digitalWrite(led, HIGH);
    Serial.print(lyrics_chorus[c]);
    tone(piezo, song1_chorus_melody[b], notelength);
    c++;
  }
  b++;
  if (b >= sizeof(song1_chorus_melody) / sizeof(int)) {
    Serial.println("");
    a++;
    b = 0;
    c = 0;
  }
}
delay(notelength); // necessary because piezo is on independent timer
noTone(piezo);
digitalWrite(led, LOW);
delay(notelength * beatseparationconstant); // create separation between notes
if (a == 7) { // loop back around to beginning of song
  a = 1;
}
}