Getting Started

Chapter 8: C Pointers and Arrays

tion

is the

should be played. Play_Tune gets the

to the Duration variable and the Timer1

its. When called again by Timer0, if the

ed and the function exits leaving the tone

d to 0, Play_Tune gets the next set of

Duration and the timer and starts the next tone. If the Duration

es that the tune has been played through,

xt byte and if that byte is 1, it starts the tune over, if 0 it ends

une. Clever, eh?

ray – Fur Elise

e[] PROGMEM=

, 8,xd2, 8,e2, 8,b1, 8,d2, 8,c2, 4,a1,

8 e1, 8,a1, 4,b1, 8,p, 8,e1, 8,xg1, 8,b1, 4,c2,

, 8,xd2, 8,e2, 8,xd2, 8,e2, 8,b1, 8,d2,

8,c1, 8,e1, 8,a1, 4,b1, 8,p, 8,e1, 8,c2,

8,b1, 4,a1,

0, 1

to make sound

e large black square on the back of the Butterfly. It

at deforms when electricity is applied to it (the

ation can be made at audio frequencies allowing

nd waves in the air. Our piezo-element is connected to

the OC1A pin that can be configured as an output for

Timer1 waveform generator. We will configure the Timer1 waveform

ill use PWM to generate tones.

Setting the dura

The duration and the frequency are paired values in the table. The duration
length of time that the following tone
duration
and tone from the table and loads them in
top count. It starts the tone and then ex
Duration is not 0, Duration is decrement
playing. When Duration is decremente
values for the
value read from the table is 0, this indicat
so it checks the ne
the t

An example song ar

const int FurElis

{

3,

8,e2, 8,xd2, 8,e2

8,p, 8,c1, ,

8,p, 8,e1, ,e8 2

8,c2, 4,a1, 8,p,

};

Using the Piezo-element

The piezo-element is th
contains a sheet of material th
piezo electric effect). This deform
the element to produce sou
PortB pin 5, which is also
the
generator so that it w