7540 datasheet(174/366 Pages) RENESAS

174 / 366 page

2-98

REJ09B0018-0200Z

Rev.2.00

Jun 21, 2004

APPLICATION

7540 Group

2.5 Timer Y and timer Z

Fig. 2.5.40 Example of control procedure

Wait one-shot generation routine

INT0 rising edge active

Timer Z interrupt processing routine

RTI

RTS

Timer Z primary (Address 2716)

Prescaler Z (Address 2516)

Set pull-up control register

Set port P1P3 control register

TYZM(Address 2016)

Timer Z count start (Note 7)

Set the standby state to accept

one-shot start trigger

INTEDGE(Address 3A16)

Set interrupt edge selection register

Change of timer Z

Timer Z primary waveform

generation not extended (Note 2)

Timer Z secondary waveform

generation not extended (Note 2)

Initial state: TZP: “H” interval,

TZS: “L” interval after underflow

Stop at “H” after underflow

INT0 pin one-shot trigger valid (Note 3)

INT0 pin rising edge trigger (Note 3)

PUM(Address 2416)

TCSS(Address 2E16)

Timer Z count source selected

Set port P02 to the output mode.

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

(Timer Z interrupt disabled)

Set value to timer Z (Notes 2, 4, 5, 6)

Set timer count source set register (Note 3)

TYZM(Address 2016)

Set timer Y, Z mode register

Programmable wait one-shot

generation mode

Writing to only latch (Note 2)

Timer Z count stop

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

(Timer Z interrupt enabled)

Set “0” to the imer Z interrupt request bit.

Set timer Y, Z waveform output control register

Set port P37 to the input mode.

Notes 1: When using this mode, be sure to select “write to latch only”.

2: The waveform extension function by the timer Z waveform

extension control bits can be used only when “0016” is set to

prescaler Z.

When the value other than “0016” is set to prescaler Z, be

sure to set “0” to EXPZP and EXPZS. Also, when the timer Y

underflow is selected as the timer Z count source, the

waveform extension function cannot be used.

3: Stop timer Z to change the INT0 pin one-shot trigger control

bit and INT0 one-shot trigger active edge selection bit.

4: In the programmable wait one-shot generation mode, values

of TZS, EXPZP, and EXPZS are valid by writing to TZP.

Even when changing TZP is not required, write the same

value again.

5: In the programmable wait one-shot generation mode, when

the setting value is changed while the waveform is output, set

by software in order not to execute the writing to TZP and the

timing of timer Z underflow simultanesously.

6: Count values of the primary interval (during wait) and

secondary interval (during one-shot output) can be checked

by reading TZP (TZS is undefined at read).

7: In this state, timer count is not started.

Timer Z secondary (Address 2616)

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