7643 datasheet(137/424 Pages) RENESAS

137 / 424 page

Rev.2.00

Aug 28, 2006

page 16 of 202

7643 Group

REJ09B0133-0200

APPLICATION

2.2 Timer

(2)

Timer application example 1: Clock function (measurement of 1 s)

Outline: The input clock is divided by the timer so that the clock can count up at 1 s intervals.

Specifications: •The clock f(XCIN) = 32 kHz is divided by the timer.

•The timer 2 interrupt request bit is checked in main routine, and if the interrupt

request is issued, the clock is counted up.

• The timer 1 interrupt occurs every 10 ms to execute processing of other interrupts.

Figure 2.2.8 shows the timers connection and setting of division ratios; Figure 2.2.9 shows the

related registers setting; Figure 2.2.10 shows the control procedure.

Fig. 2.2.8 Timers connection and setting of division ratios

2.2.3 Timer application examples

(1) Basic functions and uses

[Function 1] Control of event interval (Timer 1 to Timer 3)

When a certain time, by setting a count value to each timer, has passed, the timer interrupt request occurs.

<Use>

•Generating of an output signal timing

•Generating of a wait time

[Function 2] Control of cyclic operation (Timer 1 to Timer 3)

The value of the timer latch is automatically written to the corresponding timer each time the

timer

underflows, and each timer interrupt request occurs in cycles.

<Use>

•Generating of cyclic interrupts

•Clock function (measurement of 1 s); see “(2) Timer application example 1”

•Control of a main routine cycle

[Function 3] Output of rectangular waveform

(Timer 1, Timer 2)

The output levels of the TOUT pin is inverted each time the timer underflows.

<Use>

•Piezoelectric buzzer output; see “(3) Timer application example 2”

•Generating of the remote control carrier waveforms

f(XCIN)

32 kHz

10 ms

1/2

1/160

1/100

0/1

0 : No interrupt request issued

1 : Interrupt request issued

1 s

Timer 1

Timer 1 interrupt

request bit

Timer 2

Timer 2 interrupt request bit

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