M38039G8HKP datasheet(30/92 Pages) RENESAS

30 / 92 page

Rev.1.10

Nov 14, 2005

Page 30 of 91

REJ03B0166-0110

3803 Group (Spec.H QzROM version)

PRELIMINARY

Notice: This is not a final specification.

Some parametric limits are subject to change.

(4) Pulse Width Measurement Mode

• Mode selection

This mode can be selected by setting “11” to the timer X

operating mode bits (bits 1 and 0) and the timer Y operating

mode bits (bits 5 and 4) of the timer XY mode register (address

002316).

• Explanation of operation

When the CNTR0 active edge switch bit (bit 2) or the CNTR1

active edge switch bit (bit 6) of the timer XY mode register

(address 002316) is “1”, the timer counts during the term of one

falling edge of CNTR0/CNTR1 pin input until the next rising

edge of input (“L” term). When it is “0”, the timer counts during

the term of one rising edge input until the next falling edge input

(“H” term).

• Precautions

Set the double-function port of CNTR0/CNTR1 pin and port

P54/P55 to input in this mode.

The count operation can be stopped by setting “1” to the timer X

count stop bit (bit 3) and the timer Y count stop bit (bit 7) of the

timer XY mode register (address 002316). The interrupt request

bit is set to “1” each time the timer underflows.

• Precautions when switching count source

When switching the count source by the timer 12, X and Y 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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