Rev.1.10
Apr 3, 2006
page 28 of 75
REJ03B0139-0110
3858 Group
(4) Pulse period measurement mode
qMode selection
This mode can be selected by setting “010” to the timer Z1 operat-
ing mode bits (bits 2 to 0) and setting “0” to the timer/event
counter mode switch bit (b7) of the timer Z1 mode register (ad-
dress 002816).
qCount source selection
In high-, or middle-speed mode, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/
128, 1/256, 1/512 or 1/1024 of f(XIN); or f(XCIN) can be selected as
the count source.
In low-speed mode, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/128, 1/256,
1/512 or 1/1024 of f(XCIN); or f(XCIN) can be selected as the count
source.
qInterrupt
The interrupt at an underflow is the same as the timer mode’s.
When the pulse period measurement is completed, the timer Z1/
CNTR2 interrupt request bit (bit 1) of the interrupt request register
1 (address 003C16) is set to “1”.
qExplanation of operation
The cycle of the pulse which is input from the CNTR2 pin is mea-
sured. When the CNTR2 active edge switch bit (bit 5) of the timer
Z1 mode register (address 002816) is “0”, the timer counts during
the term from one falling edge of CNTR2 pin input to the next fall-
ing edge. When it is “1”, the timer counts during the term from one
rising edge input to the next rising edge input.
When the valid edge of measurement completion/start is detected,
the 1’s complement of the timer value is written to the timer latch
and “FFFF16” is set to the timer.
Furthermore when the timer underflows, the timer Z1 interrupt re-
quest occurs and “FFFF16” is set to the timer. When reading the
timer Z1, the value of the timer latch (measured value) is read.
The measured value is retained until the next measurement
completion.
sPrecautions
Set the double-function port of CNTR2 pin and port P22 to input in
this mode.
A read-out of timer value is impossible in this mode. The timer can
be written to only during timer stop (no measurement of pulse pe-
riod).
Since the timer latch in this mode is specialized for the read-out of
measured values, do not perform any write operation during mea-
surement.
“FFFF16” is set to the timer when the timer underflows or when the
valid edge of measurement start/completion is detected. Conse-
quently, the timer value at start of pulse period measurement
depends on the timer value just before measurement start.
Figure 24 shows the timing chart of the pulse period measurement
mode.
(5) Pulse width measurement mode
qMode selection
This mode can be selected by setting “011” to the timer Z1 operat-
ing mode bits (bits 2 to 0) and setting “0” to the timer/event
counter mode switch bit (b7) of the timer Z1 mode register (ad-
dress 002816).
qCount source selection
In high-, or middle-speed mode, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/
128, 1/256, 1/512 or 1/1024 of f(XIN); or f(XCIN) can be selected as
the count source.
In low-speed mode, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64, 1/128, 1/256,
1/512 or 1/1024 of f(XCIN); or f(XCIN) can be selected as the count
source.
qInterrupt
The interrupt at an underflow is the same as the timer mode’s.
When the pulse widths measurement is completed, the timer Z1/
CNTR2 interrupt request bit (bit 1) of the interrupt request register
2 (address 003C16) is set to “1”.
qExplanation of operation
The pulse width which is input from the CNTR2 pin is measured.
When the CNTR2 active edge switch bit (bit 5) of the timer Z1
mode register (address 002816) is “0”, the timer counts during the
term from one rising edge input to the next falling edge input (“H”
term). When it is “1”, the timer counts during the term from one
falling edge of CNTR2 pin input to the next rising edge of input (“L”
term).
When the valid edge of measurement completion is detected, the
1’s complement of the timer value is written to the timer latch.
When the valid edge of measurement completion/start is detected,
“FFFF16” is set to the timer.
When the timer Z1 underflows, the timer Z1 interrupt occurs and
“FFFF16” is set to the timer Z1. When reading the timer Z1, the
value of the timer latch (measured value) is read. The measured
value is retained until the next measurement completion.
sPrecautions
Set the double-function port of CNTR2 pin and port P22 to input in
this mode.
A read-out of timer value is impossible in this mode. The timer can
be written to only during timer stop (no measurement of pulse
widths).
Since the timer latch in this mode is specialized for the read-out of
measured values, do not perform any write operation during mea-
surement.
“FFFF16” is set to the timer when the timer underflows or when the
valid edge of measurement start/completion is detected. Conse-
quently, the timer value at start of pulse width measurement
depends on the timer value just before measurement start.
Figure 25 shows the timing chart of the pulse width measurement
mode.