Circuit 06 – Piezo Tunes

Having explored Motion, Light and Electrons we are now going to look at Sound using a simple circuit consisting of a single Piezo element.  Even though the output of the Arduino is digital because of its speed it is possible to produce music by pulsing a piezo element at the right frequency.The tone of each note is calculated using:

timeHigh = period / 2 = 1 / (2 * toneFrequency)

which allows us to produce the following notes:

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

The following code will play Twinkle Twinkle little star. The four functions are generic but the four lines at the top are what determines the tune played.  For example, the following is the first line from Happy Birthday

char notes[] = {"ccdcfeccdcgf "};
int beats[] = {1,1,1,1,1,2,1,1,1,1,1,2,4};