7540 datasheet(125/366 Pages) RENESAS

125 / 366 page

2-49

REJ09B0018-0200Z

Rev.2.00

Jun 21, 2004

7540 Group

APPLICATION

2.4 Timer X

Fig. 2.4.12 Example of control procedure

“FF16”

CLI

RESET

Timer X interrupt processing routine

RTI

TCSS(Address 2E16)

Timer X count source:

f(XIN)/16 selected

Set timer count source set register

TXM(Address 2B16)

Setting clock is required?

Processing

Processing of setting clock

Clock is stopped?

Processing of clock setting

Clock setting

RTS

Set “0” to the timer X interrupt enable bit.

(Timer X interrupt disabled)

Prescaler X (Address 2C16)

Set value to timer X (Note 2)

Set “0” to the timer X interrupt request bit.

TXM(Address 2B16)

Timer mode

Timer X count stop

Set timer X mode register

Initialization

SEI

CLD

CLT

CPUM(Address 3B16)

← 10000X002

Wait until f(XIN) oscillation is stabilized (Note 1)

CPUM(Address 3B16)

← 00000X002

Timer X (Address 2D16)

Set “1” to the timer X interrupt enable bit.

(Timer X interrupt enabled)

Timer X count start

Set timer X mode register

X: This bit is not used here. Set it to “0” or “1” arbitrary.

Notes 1: For the concrete time, ask the oscillator manufacture.

2: About 250 ms = 1/4.19 MHz ✕ 16 ✕ (FF16 + 1) ✕ (FF16 + 1)

Timer X

setting value

“FF16”

Clock count up (1/4 s to year)

Set “0” to the timer X interrupt enable bit.

(Timer X interrupt disabled)

TXM(Address 2B16)

Timer X count start

Set timer X mode register

TXM(Address 2B16)

Timer X count stop

Set timer X mode register

“FF16”

Prescaler X (Address 2C16)

Set value to timer X (Note 2)

Set “0” to the timer X interrupt request bit.

Timer X (Address 2D16)

Set “1” to the timer X interrupt enable bit.

(Timer X interrupt enabled)

“FF16”

Timer X

division ratio

Prescaler X

setting value

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