38C3 datasheet(85/224 Pages) RENESAS

Part #	38C3

Description	8-BIT SINGLE-CHIP MICROCOMPUTER 740 FAMILY / 38000 SERIES

PDF	224 Pages

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Manufacturer	RENESAS [Renesas Technology Corp]

Direct Link	http://www.renesas.com

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85 / 224 page

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38C3 Group User’s Manual

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(XIN) = 4.19 MHz (222 Hz) is divided by the timer.

•The timer 3 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 244

µs to execute processing of other interrupts.

Figure 2.2.16 shows the timers connection and setting of division ratios; Figure 2.2.17 shows the

relevant registers setting; Figure 2.2.18 shows the control procedure.

Fig. 2.2.16 Timers connection and setting of division ratios

f(XIN)

4.19 MHz

244

µs

1/16

1/64

1/256

1/160/1

0/1

0 : No interrupt request issued

1 : Interrupt request issued

1 second

Timer 1

Timer 1 interrupt

request bit

Timer 2Timer 3

Timer 3 interrupt request bit

Timer 1 count

source selection bit

38C3 Datasheet(PDF) 85 Page - Renesas Technology Corp