M38044F0HKP datasheet(170/387 Pages) RENESAS

170 / 387 page

2-46

APPLICATION

2.3 Timer

Rev.1.00 Jan 14, 2005

REJ09B0212-0100Z

3804 Group (Spec.H)

(6)

All modes

qTimer Z write control

Which write control can be selected by the timer Z write control bit (bit 3) of the timer Z mode

data only to the latch.

When the operation “writing data only to the latch” is selected, the value is set to the timer latch

by writing data to the address of timer Z and the timer is updated at next underflow. After reset

release, the operation “writing data to both the latch and the timer at the same time” is selected,

and the value is set to both the latch and the timer at the same time by writing data to the address

of timer Z.

In the case of writing data only to the latch, if writing data to the latch and an underflow are

performed almost at the same time, the timer value may become undefined.

qTimer Z read control

A read-out of timer value is impossible in pulse period measurement mode and pulse width measurement

mode. In the other modes, a read-out of timer value is possible regardless of count operating or

stopped.

However, a read-out of timer latch value is impossible.

qSwitch of interrupt active edge of CNTR2 and INT1

Each interrupt active edge depends on setting of the CNTR2 active edge switch bit and the INT1

active edge selection bit.

qSwitch of count source

When switching the count source by the timer Z count source selection bits, the value of timer

count is altered in inconsiderable amount owing to generating of thin pulses on the count input

signals.

Therefore, select the timer count source before setting the value to the prescaler and the timer.

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