M38002M4 Datasheet, PDF (63/173 Pages) Mitsubishi Electric Semiconductor – 8-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
2.2 Timer
(3) Timer application example 2 : Piezoelectric buzzer output
Outline : The rectangular waveform output function of a timer is applied for a piezoelectric buzzer
output.
Specifications : • The rectangular waveform resulting from dividing clock f(XIN) = 4.19 MHz into about
2 kHz (2048 Hz) is output from the P54/CNTR0 pin.
• The level of the P54/CNTR0 pin fixes to “H” while a piezoelectric buzzer output is
stopped.
Figure 2.2.13 shows an example of a peripheral circuit, and Figure 2.2.14 shows a connection of the
timer and setting of the division ratio.
CNTR0 output
The “H” level is output while a piezoelectric buzzer output is stopped.
3800 group
244 µs 244 µs
P54/CNTR0
PiPiPi....
Set a division ratio so that the underflow output cycle of the Timer X becomes this value.
Fig. 2.2.13 Example of a peripheral circuit
f(XIN) = 4.19 MHz
Fixed
1/16
Prescaler X
1
Timer X
1/64
Fixed
1/2
CNTR0
Fig. 2.2.14 Connection of the timer and setting of the division ratio [Piezoelectric buzzer output]
3800 GROUP USER’S MANUAL
2-15