// This code plays a simple melody on the ATtiny85.

// The melody is stored in a string called "melody".
const char melody[] = "CDEFGABcdefgab";

// The duration of each note is stored in a string called "durations".
const char durations[] = "444444444444";

// The tempo is stored in a variable called "tempo".
int tempo = 120;

// This function plays a note.
void playNote(char note, char duration) {
  // Get the frequency of the note.
  int frequency = noteToFrequency(note);

  // Play the note for the specified duration.
  tone(6, frequency, duration);
}

// This function converts a note name to a frequency.
int noteToFrequency(char note) {
  switch (note) {
    case 'C': return 261;
    case 'D': return 294;
    case 'E': return 329;
    case 'F': return 349;
    case 'G': return 392;
    case 'A': return 436;
    case 'B': return 494;
    default: return 0;
  }
}

// This function sets up the ATtiny85.
void setup() {
  // Set the pin mode of the speaker pin.
  pinMode(6, OUTPUT);
}

// This function plays the melody.
void loop() {
  // For each note in the melody...
  for (int i = 0; i < strlen(melody); i++) {
    // Play the note.
    playNote(melody[i], durations[i]);

    // Wait for the note to finish playing.
    delay(durationToMs(durations[i]));
  }
}

// This function converts a duration to milliseconds.
int durationToMs(char duration) {
  switch (duration) {
    case '4': return 400;
    case '8': return 200;
    case '16': 100;
    case '32': 50;
    default: return 0;
  }
}