7540 datasheet(167/366 Pages) RENESAS

167 / 366 page

2-91

REJ09B0018-0200Z

Rev.2.00

Jun 21, 2004

7540 Group

APPLICATION

2.5 Timer Y and timer Z

2.5.6 Programmable wait one-shot generation mode (timer Z)

(1) Operation description

In the programmable wait one-shot generation mode, the one-shot pulse by the setting value of timer

Z secondary (TZS) can be output from P02/TZOUT pin by software or external trigger to P37/INT0 pin

after the wait by the setting value of the timer Z primary (TZP). When using this mode, be sure to

set “1” to the timer Z write control bit to select “write to latch only”. Also, set the port P02 direction

registers to output mode.

The active edge of output waveform is set by the timer Z output level latch. When “0” is set to the

timer Z output level latch, after the wait during the interval of the TZP setting value, “H” pulse during

the interval of the TZS setting value is output. When “1” is set to the timer Z output level latch, after

the wait during the interval of the TZP setting value, “L” pulse during the interval of the TZS setting

value is output.

Also, in this mode, the intervals of the wait and the one-shot pulse output can be extended for 0.5

cycle of timer count source clock by setting the timer Z primary waveform extension control bit

(EXPZP) and the timer Z secondary waveform extension control bit (EXPZS) to “1”. As a result, the

waveforms of more accurate resolution can be output.

In the programmable wait one-shot generation mode, the trigger by software or the external INT0 pin

can be accepted by writing “0” to the timer Z count stop bit after the count value is set. (At the time

when “0” is written to the timer Z count stop bit, Timer Z stops.)

By writing “1” to the timer Z one-shot start bit, or by inputting the valid trigger to the INT0 pin after

the trigger to the INT0 pin becomes valid by writing “1” to the INT0 pin one-shot trigger control bit,

Timer Z starts counting.

While Timer Z counts the TZP, the initial value of the TZOUT pin output is retained. When Timer Z

underflows, the value of TZS is reloaded, at the same time, the output of TZOUT pin is inverted.

When Timer Z underflows, the output of TZOUT pin is inverted again and Timer Z stops. When also

the trigger of INT0 pin is accepted, the contents of the one-shot start bit is changed to “1” by

hardware.

The falling or rising can be selected as the edge of the valid trigger of INT0 pin by the INT0 pin one-

shot trigger edge selection bit.

During the wait interval and the one-shot pulse output interval, the one-shot pulse output can be

stopped forcibly by writing “0” to the timer Z one-shot start bit.

In the programmable wait one-shot generation mode, when the count values are changed, set values

to the TZS, EXPZP and EXPZS first. After then, set the value to TZP. The values are set all at once

at the beginning of the next wait interval when the value is set to TZP. (When writing at timer stop

is executed, writing to TZP at last is required.)

Timer Z can stop counting by setting “1” to the timer Z count stop bit.

Also, when timer Z underflows, the timer Z interrupt request bit is set to “1”.

Timer Z reloads the value of latch when counting is stopped by the timer Z count stop bit.

(When timer is read out while timer is stopped, the value of latch is read. The value of timer can be

read out only while timer is operating.)

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