Musical Treasure Box

/******************************************************************
 * SparkFun Inventor"s Kit
 * Example sketch 11
 * 
 * BUZZER
 * with lots of help from the Arduino community,
 * and amended by J. Hadley to include an extra octave and semitones.
 * Further amended August 2020 to allow the playing of a song to be
 * interrupted by a sensor input. When the sensor value meets the
 * condition, the song will cease playing.
 * 
 * This sketch uses the buzzer to play songs.
 * The Arduino"s tone() command will play notes of a given frequency.
 * 
 * This sketch was written by SparkFun Electronics,
 * (This sketch was originally developed by D. Cuartielles for K3)
 * This code is completely free for any use.
 * Visit http://learn.sparkfun.com/products/2 for SIK information.
 * Visit http://www.arduino.cc to learn about the Arduino.
 * 
 * Version 2.0 6/2012 MDG
 * Version 2.1 9/2014 BCH
 *****************************************************************/


const int SensorPin = A4;   // switch to use a different analog sensor
int sensorThreshold = 500;  // what sensor value will stop the song
const int buzzerPin = 3;    // connect the buzzer to pin 3 (Thinkershield buzzer pin)
int tempo = 270;            // The tempo is how fast to play the song (beats per minute).
const int songLength = 19;  // sets the number of notes of the song

// Notes is an array of text characters corresponding to the notes
// in your song. A space represents a rest (no tone). Each note or rest must be separated by a comma
// with no comma after the last note.

// It"s important that you use single quotes for single letters like "b", "g" and the rest ' ', and
// that you use double quotes for notes requiring multiple letters like "g2" (which is the g in the octave above)
// and "f#" (which is the sharp - a semitone above "f") in the lower octave. Your code may compile if these are
// incorrect but those notes will not play. It is a quirky part of the Arduino coding language in this IDE.
// In Tinkercad, it works differently and all notes should be enclosed in double quotes.

char* notes[songLength] = {
  ' ', 
  "f#", "g#", 'b', 'b', ' ', 
  "d2#", "f2#", "g2#", "g2#", ' ', 
  "g2#", "f2#", "f2#", "e2", ' ', 
  "e2", "d2#", "d2#"}; 

// beats[] is an array of values for each note. A "1" represents a quarter-note, 
// "2" a half-note, and "4" a full-note.
// Don"t forget that the rests (spaces) need a length as well.

int beats[songLength] = {
  2, 
  1, 1, 2, 3, 2, 
  1, 1, 2, 3, 2, 
  1.5, 0.5, 1, 3.5, 2, 
  1.5, 1, 3.5};

void setup() 
{
  pinMode(buzzerPin, OUTPUT);  // sets the  buzzer pin as an OUTPUT
  pinMode(SensorPin, INPUT);
  //Serial.begin(9600);
}

void loop() 
{
  int i, duration; 
  bool keepPlaying = true;
  int value;
  
  i=0;
  value = analogRead(SensorPin);
  //Serial.println(value);
  keepPlaying = (value > sensorThreshold);
  
  while ((i < songLength) && keepPlaying)
  {
    //Serial.println("playing");
    duration = beats[i] * tempo;  // length of note/rest in ms

    if (notes[i] == ' '){          // is this a rest? 
      delay(duration);            // then pause for a moment
      //Serial.println("pause");
    }
    else                          // otherwise, play the note
    {
      tone(buzzerPin, frequency(notes[i]), duration);
      delay(duration);            // wait for tone to finish
      //Serial.println("note is " + String(notes[i]));
    }

    delay(tempo/20);              // brief pause between notes
    value = analogRead(SensorPin);
    keepPlaying = (value > sensorThreshold);
    //Serial.println(value);
    i = i+1;  
  }

  //while(true){
  // We only want to play the song once, so we pause forever
  //}
  
  /* If you'd like your song to play once only, uncomment the 3 lines that make up the 
     while(true)statement above. When commented out, the song will play repeatedly. */
}

//-------------------------------------------------------------------------------------------------------------------------
int frequency(char* note) 
{
  int i;
  const int numNotes = 25;  // number of notes we"re storing - includes the semitones over 2 octaves starting at middle C
  char* names[numNotes] = { 
    'c', "c#", 'd', "d#",'e', 'f', "f#", 'g', "g#", 'a', "a#", 'b', "c2", "c2#", "d2", "d2#", "e2", "f2", "f2#", "g2", "g2#", "a2", "a2#", "b2", "c3"    };
  int frequencies[numNotes] = {
    262, 277, 294, 311, 330, 349, 370, 392, 415, 440, 466, 494, 523, 554, 587, 622, 659, 698, 740, 784, 831, 880, 932, 988, 1047    };

  // Now we"ll search through the letters in the array, and if
  // we find it, we"ll return the frequency for that note.

  for (i = 0; i < numNotes; i++)  // Step through the notes
  {
    if (names[i] == note)         // Is this the one?
    {
      return(frequencies[i]);     // Yes! Return the frequency and exit function.
    }
  }
  return(0);  // We looked through everything and didn't find it,
  // but we still need to return a value, so return 0.
}