M38049FEHKP datasheet(27/116 Pages) RENESAS

27 / 116 page

Rev.1.01

Jan 25, 2005

page 27 of 114

REJ03B0131-0101Z

3804 Group (Spec. H)

(3) Event counter mode

qMode selection

This mode can be selected by setting “10” 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).

qExplanation of operation

The operation is the same as the timer mode’s except that the

timer counts signals input from the CNTR0 or CNTR1 pin. The

valid edge for the count operation depends on 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). When it is “0”, the

rising edge is valid. When it is “1”, the falling edge is valid.

sPrecautions

Set the double-function port of CNTR0/CNTR1 pin and port P54/

P55 to input in this mode.

(4) Pulse width measurement mode

qMode 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).

qExplanation of operation

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

tive 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).

sPrecautions

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 incon-

siderable 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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