7540 datasheet(129/366 Pages) RENESAS

129 / 366 page

2-53

REJ09B0018-0200Z

Rev.2.00

Jun 21, 2004

7540 Group

APPLICATION

2.4 Timer X

Fig. 2.4.17 Example of control procedure

“0116”

“7C16”

TXM(Address 2B16)

RESET

TCSS(Address 2E16)

Timer X count source:

f(XIN)/2 selected

Buzzer output is requested?

Processing

“7C16”

Timer X (Address 2D16)

CLI

Timer X count is stopped?

Processing

Timer X count is operating?

Buzzer output processing

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)

← 11000X002

Set timer X mode register

TXM(Address 2B16)

Timer X count start

Pulse output mode

Output is started at “H” level

Timer X count stop

Set timer X mode register

Set port P14 to the output 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: 125

µs = 1/4 MHz ✕ 2 ✕ (0116 + 1) ✕ (7C16 + 1)

Prescaler X (Address 2C16)

Set value to timer X (Notes 2, 3)

Timer X (Address 2D16)

Set “1” to port P14. (“H” output)

Set timer count source set register

Set timer X mode register

TXM(Address 2B16)

Timer X count stop

Set value to timer X (Note 3)

3: The output level of P14/CNTR0 pin is initialized by writing to timer X.

Prescaler X

setting

value

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