3858 Group
(4) Pulse period measurement mode
■Mode selection
(5) Pulse width measurement mode
■Mode selection
This mode can be selected by setting “010” to the timer Z2 operat-
ing mode bits (bits 2 to 0) and setting “0” to the timer/event
counter mode switch bit (b7) of the timer Z2 mode register (ad-
dress 002B16).
This mode can be selected by setting “011” to the timer Z2 operat-
ing mode bits (bits 2 to 0) and setting “0” to the timer/event
counter mode switch bit (b7) of the timer Z2 mode register (ad-
dress 002B16).
■Count source selection
■Count 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 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.
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.
■Interrupt
■Interrupt
The interrupt at an underflow is the same as the timer mode’s.
When the pulse period measurement is completed, the timer Z2/
CNTR3 interrupt request bit (bit 1) of the interrupt request register
1 (address 003C16) is set to “1”.
The interrupt at an underflow is the same as the timer mode’s.
When the pulse widths measurement is completed, the timer Z2/
CNTR3 interrupt request bit (bit 1) of the interrupt request register
1 (address 003C16) is set to “1”.
■Explanation of operation
■Explanation of operation
The cycle of the pulse which is input from the CNTR3 pin is mea-
sured. When the CNTR3 active edge switch bit (bit 5) of the timer
Z2 mode register (address 002B16) is “0”, the timer counts during
the term from one falling edge of CNTR3 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.
The pulse width which is input from the CNTR3 pin is measured.
When the CNTR3 active edge switch bit (bit 5) of the timer Z2
mode register (address 002B16) 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 CNTR3 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.
Furthermore when the timer underflows, the timer Z2 interrupt re-
quest occurs and “FFFF16” is set to the timer. When reading the
timer Z2, the value of the timer latch (measured value) is read.
The measured value is retained until the next measurement
completion.
When the timer Z2 underflows, the timer Z2 interrupt occurs and
“FFFF16” is set to the timer Z2. When reading the timer Z2, the
value of the timer latch (measured value) is read. The measured
value is retained until the next measurement completion.
■Precautions
■Precautions
Set the double-function port of CNTR3 pin and port P23 to input in
this mode.
Set the double-function port of CNTR3 pin and port P23 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).
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.
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 32 shows the timing chart of the pulse period measurement
mode.
“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 33 shows the timing chart of the pulse width measurement
mode.
Rev.1.10 Apr 3, 2006 page 36 of 75
REJ03B0139-0110
RENESAS [ RENESAS TECHNOLOGY CORP ]
