7540 datasheet(101/366 Pages) RENESAS

101 / 366 page

2-25

REJ09B0018-0200Z

Rev.2.00

Jun 21, 2004

7540 Group

APPLICATION

2.2 Timer A

Fig. 2.2.16 Example of control procedure

“FF16”

Set timer A mode register

TAM(Address 1D16)

Timer A count start

CLI

RESET

SEI

CLD

CLT

CPUM (Address 3B16)

← 10000X002

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

CPUM (Address 3B16)

← 00000X002

Processing

Timer A interrupt processing routine

Error processing

RTI

TAM(Address 1D16)

Period measurement mode

Rising period measured

Rising edge active for CNTR1

interrupt

Timer A count stop

Set timer A mode register

1 1

Set port P00 to the input mode.

PULL(Address 1616)

P00 pull-up control bit

0: Pull-up Off

1: Pull-up On

Set pull-up control register

CNTR1 interrupt processing routine

Read timer A (Note 3)

RTI

Error processing at incorrect period input

INTEDGE(Address 3A16)

Key-on wakeup disabled

CNTR1 interrupt processing

Timer A interrupt processing

Set “0” to the CNTR1 interrupt enable bit.

(CNTR1 interrupt disabled)

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

(Timer A 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: When setting the value to timer A, set in order of low-order byte

and high-order byte following.

3: When reading a value of timer A, read in order of high-order byte

and low-order byte following.

Timer A (low-order) (Address 1E16)

Set value to timer A (Note 2)

Timer A (high-order) (Address 1F16)

Set interrupt edge selection register

Set “1” to the CNTR1 interrupt enable bit.

(CNTR1 interrupt enabled)

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

(Timer A interrupt enabled)

Set “0” to the CNTR1 interrupt request bit.

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

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