M38C31M7AXXXFS datasheet(88/224 Pages) RENESAS

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38C3 Group User’s Manual

APPLICATION

2-23

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 P42/T3OUT pin.

•The level of the P42/T3OUT pin is fixed to “H” while a piezoelectric buzzer output

stops.

Figure 2.2.19 shows a peripheral circuit example, and Figure 2.2.20 shows the timers connection and

setting of division ratios. Figures 2.2.21 shows the relevant registers setting, and Figure 2.2.22

shows the control procedure.

Fig. 2.2.19 Peripheral circuit example

Fig. 2.2.20 Timers connection and setting of division ratios

38C3 Group

T3OUT

PiPiPi.....

244

µs

T3OUT 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 3 can be 244

µs.

f(XIN)

4.19 MHz

1/161/64

1/2

T3OUT

Timer 3Fixed

Timer 3 count source

selection bit

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