Arduino Challenge - Jingle Bells

Problem Statement

Connect a Piezo speaker to an Arduino board and make it play the first four measures of Jingle Bells.

Key Facts

·         The notes to Jingle Bells are:

Note:	E	E	E	E	E	E	E	G	D	E
Counts:	1	1	2	1	1	2	1	1	1	4

·         Assume counts are for 250 to 300 ms.

Solution (Physical World)

The speaker should sing Jingle Bells.

Code

/* Melody
 * (cleft) 2005 D. Cuartielles for K3
 *
 * This example uses a piezo speaker to play melodies.  It sends
 * a square wave of the appropriate frequency to the piezo, generating
 * the corresponding tone.
 *
 * The calculation of the tones is made following the mathematical
 * operation:
 *
 *       timeHigh = period / 2 = 1 / (2 * toneFrequency)
 *
 * where the different tones are described as in the table:
 *
 * note  frequency  period  timeHigh
 * c          261 Hz          3830  1915
 * d          294 Hz          3400  1700
 * e          329 Hz          3038  1519
 * f          349 Hz          2864  1432
 * g          392 Hz          2550  1275
 * a          440 Hz          2272  1136
 * b          493 Hz          2028 1014
 * C         523 Hz         1912  956
 *
 * http://www.arduino.cc/en/Tutorial/Melody
 */
 
int speakerPin = 9;

int length = 15; // the number of notes
char notes[] = "eeeeeeegcde "; // a space represents a rest
int beats[] = { 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 4,};
int tempo = 300;
void playTone(int tone, int duration) {
  for (long i = 0; i < duration * 1000L; i += tone * 2) {
    digitalWrite(speakerPin, HIGH);
    delayMicroseconds(tone);
    digitalWrite(speakerPin, LOW);
    delayMicroseconds(tone);
  }
}
void playNote(char note, int duration) {
  char names[] = { 'c', 'd', 'e', 'f', 'g', 'a', 'b', 'C' };
  int tones[] = { 1915, 1700, 1519, 1432, 1275, 1136, 1014, 956 };
 
  // play the tone corresponding to the note name
  for (int i = 0; i < 8; i++) {
    if (names[i] == note) {
      playTone(tones[i], duration);
    }
  }
}
void setup() {
  pinMode(speakerPin, OUTPUT);
}
void loop() {
  for (int i = 0; i < length; i++) {
    if (notes[i] == ' ') {
      delay(beats[i] * tempo); // rest
    } else {
      playNote(notes[i], beats[i] * tempo);
    }
   
    // pause between notes
    delay(tempo / 2);
  }
}