7641 datasheet(155/385 Pages) RENESAS

155 / 385 page

Rev.2.00

Aug 28, 2006

page 24 of 148

7641 Group

REJ09B0336-0200

APPLICATION

2.2 Timer

(3) Timer application example 2: Piezoelectric buzzer output

Outline: The rectangular waveform output function of the timer is applied for a piezoelectric buzzer

output.

Specifications: •The rectangular waveform, dividing the clock f(XIN) = 4.19 MHz (222 Hz) into about

2 kHz (2048 Hz), is output from the P43/CNTR0 pin.

•The level of the P43/CNTR0 pin is fixed to “H” while a piezoelectric buzzer output

stops.

Figure 2.2.15 shows a peripheral circuit example, and Figure 2.2.16 shows the timers connection and

setting of division ratios. Figure 2.2.17 shows the related registers setting, and Figure 2.2.18 shows

the control procedure.

Fig. 2.2.15 Peripheral circuit example

Fig. 2.2.16 Timers connection and setting of division ratios

7641 Group

P43/CNTR0

PiPiPi.....

244

µs

CNTR0 output

The “H” level is output while a piezoelectric buzzer output stops.

244

µs

Set a division ratio so that the underflow

output period of the timer X can be 244

µs.

f(XIN)

4.19 MHz

1/21/8

1/64

P43/CNTR0

Count source

selection

φ / 8

Timer X

1/2

Fixed

7641 Datasheet(PDF) 155 Page - Renesas Technology Corp

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