M38047FEHKP datasheet(159/387 Pages) RENESAS

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2-35

APPLICATION

2.3 Timer

Rev.1.00 Jan 14, 2005

REJ09B0212-0100Z

3804 Group (Spec.H)

(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) = 8 MHz into about 2 kHz (2049

Hz), is output from the P47/CNTR2 pin.

•The level of the P47/CNTR2 pin is fixed to “H” while a piezoelectric buzzer output

stops.

Figure 2.3.18 shows a peripheral circuit example, and Figure 2.3.19 shows the timers connection and

setting of division ratios. Figure 2.3.20 shows the relevant registers setting, and Figure 2.3.21 shows

the control procedure.

Fig. 2.3.18 Peripheral circuit example

Fig. 2.3.19 Timers connection and setting of division ratios

3804 Group (Spec. H)

P47/CNTR2

PiPiPi.....

244

µs

CNTR2 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 Z

can be 244

µs.

1/161/122

CNTR2

f(XIN) = 8 MHz

Timer Z count source

selection bit

Timer Z

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