Datasheet

Figure 19-2:
Use jumper
J12 to
connect
Piezo buzzer
on RE1 or
RC2 pin
Piezo electricity is the charge which
accumulates in certain solid materials in response
to mechanical pressure, but also providing the
charge to the piezoelectric material causes it to
physically deform. One of the most widely used
applications of piezo electricity is the production of
sound generators, called piezo buzzers. Piezo buzzer
is an electric component that comes in dierent shapes
and sizes, which can be used to create sound waves
when provided with analog electrical signal. EasyPIC
™
v7
comes with piezo buzzer which can be connected either to
RC2 or RE1 microcontroller pins, which is determined by the
position of J21 jumper. Buzzer is driven by transistor Q8 (Figure
19-1). Microcontrollers can create sound by generating a PWM (Pulse
Width Modulated) signal – a square wave signal, which is nothing more
R27
10K
Q8
BC846
R3
1K
VCC-5V
BUZZER
RE1
RC2
PZ1
BUZZER
J21
PERSPECTIVE
VIEW
TOP
VIEW
DATA BUS
In order to use the on-board Piezo Buzzer in
your application, you rst have to connect the
transistor driver of piezo buzzer to the appropriate
microcontroller pin. This is done using jumper J21.
You can place the jumper in two positions, thus
connecting the buzzer driver to either RE1 or RC2
microcontroller pin.
Buzzer starts "singing" when you provide
PWM signal from the microcontroller
to the buzzer driver. The pitch of the
sound is determined by the frequency,
and amplitude is determined by the
duty cycle of the PWM signal.
Enabling Piezo Buzzer
How to make it sing?
page 32
Figure 19-1: Piezo
buzzer connected to RE1
microcontroller pin
Piezo Buzzer
than a sequence of logic zeros and ones. Frequency of the
square signal determines the pitch of the generated sound,
and duty cycle of the signal can be used to increase or decrease
the volume in the range from 0% to 100% of the duty cycle.
You can generate PWM signal using hardware capture-compare
module, which is usually available in most microcontrollers, or
by writing a custom software which emulates the desired
signal waveform.
Supported sound frequencies
Piezo buzzer’s resonant frequency (where you can expect it's
best performance) is 3.8kHz, but you can also use it to create
sound in the range between 2kHz and 4kHz.
Freq = 3kHz, Duty Cycle = 50%
Freq = 3kHz,
Volume = 50%
Freq = 3kHz,
Volume = 80%
Freq = 3kHz,
Volume = 20%
Freq = 3kHz, Duty Cycle = 80%
Freq = 3kHz, Duty Cycle = 20%
TO SOCKETS
VCC-5V
R3
1K
PZ1
Q8
BC846
10K
R27
PERSPECTIVE
VIEW
TOP
VIEW
RE1
RC2
J21
BUZZER
TO SOCKETS
VCC-5V
R3
1K
PZ1
Q8
BC846
10K
R27
PERSPECTIVE
VIEW
TOP
VIEW
RE1
RC2
J21
BUZZER
TO SOCKETS
VCC-5V
R3
1K
PZ1
Q8
BC846
10K
R27
PERSPECTIVE
VIEW
TOP
VIEW
RE1
RC2
J21
BUZZER
modules