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Checking the operation status
The above STRT bit and STOP bit work as an operating status indication bit during reading. The value
displayed means the following description.
STRT
0
1
The same value is read from either the STRT bit or the STOP bit. If a read modify write instruction (such
as bit-processing instruction) is issued, "11
instruction.
■ Counter Clear
The 16-bit up counter is cleared to "0000
• At a reset
• Start the count when a measurement start edge is detected in the pulse width count mode.
■ Details for Pulse Width Measuring Operation
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Single measurement and continuous measurement
The pulse width count has the mode to perform the measurement once only and the mode to perform the
measurement continuously. PWCSR SC bit is used to select each mode (see "
mode"). The differences between these modes are as described below.
• Single measurement mode: When the first measurement end edge is inputted, the operation stops
• Continuous count mode: When the count end edge is inputted, the operation stops the counter count,
Be sure to select/change the measurement mode while the counter is stopped.
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Measured data
The differences between the single measurement mode and the continuous measurement mode are in
handling of a measurement result and a count value, and the PWCR function. The following describes the
differences of the measurement results in both modes.
• Single measurement mode: A count value in measuring can be obtained when PWCR is read during
• Continuous measurement mode:A measurement result in counter is transferred to PWCR when the
CHAPTER 10 PWC (Pulse Width Count: Pulse Width Measurement)
STOP
Counter stopped (except in waiting for a measurement start edge)
0
It is not active or shows that the measurement ended.
1
Counter operating, or waiting for a measurement start edge
counter count, sets the measurement end flag (EDIR) in PWCSR, and performs no
further measurement. However, if a restart occurs simultaneously, the operation
waits for a measurement start.
sets the count end flag (EDIR) in PWCSR, and stops the count until the count start
edge is inputted again. When the measurement start edge is inputted again, the
operation clears the counter to "0000
the measurement ends, the measurement result of the counter is transferred to
PWCR.
operation. A measurement result can be obtained when PWCR is read after
the measurement ends.
measurement ends.
When PWCR is read, a previous measurement result can be obtained
and held while the measurement is in progress. A count value in
measuring cannot be read.
Operating State
" is always read from these bits. Do not read by using such
B
" in the following cases.
H
", and then starts the measurement. When
H
■
Selects the operation
195
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