7540 datasheet(137/366 Pages) RENESAS

137 / 366 page

2-61

REJ09B0018-0200Z

Rev.2.00

Jun 21, 2004

7540 Group

APPLICATION

2.4 Timer X

Fig. 2.4.26 Example of control procedure

“FF16”

END

RESET

CLI

Processing

Timer X interrupt processing

CNTR0 interrupt processing

Timer X interrupt processing routine

Error processing

RTI

CNTR0 interrupt processing routine

Timer X is read out.

RTI

TXM(Address 2B16)

TCSS(Address 2E16)

Timer Y count source:

f(XIN)/16 selected

Timer X

division

ratio

Timer X

setting

value

SEI

CLD

CLT

CPUM(Address 3B16)

← 10000X002

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

CPUM(Address 3B16)

← 00000X002

Pulse width measurement mode

Falling edge

Timer X count stop

Set timer X mode register

Set port P14 to the input mode.

Set “0” to the CNTR0 interrupt enable bit.

(CNTR0 interrupt disabled)

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

(Timer X interrupt disabled)

Initialization

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)

Prescaler X (Address 2C16)

Set value to timer X (Note 2)

Timer X (Address 2D16)

Set timer count source set register

Prescaler X

setting

value

Set “1” to the CNTR0 interrupt enable bit.

(CNTR0 interrupt enabled)

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

(Timer X interrupt enabled)

Set “0” to the CNTR0 interrupt request bit.

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

TXM(Address 2B16)

Timer X count start

Set timer X mode register

Error processing at incorrect period input

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