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CHAPTER 16 PWC Timer
16.6.4
Pulse Width Measurement Mode Operation
The signal for pulse-width measurement is input from the PWI pin.
The pulse-width measurement mode includes the single measurement mode in which
the count is performed only once and continuous measurement mode in which the
pulse width is continuously measured.
■ Single Measurement Mode and Continuous Measurement Mode
The differences between the single measurement mode and continuous measurement mode are as follows:
●
Single measurement mode
When the first count end edge is input, the timer discontinues the count, the count end flag (EDIR) of
PWCSH0/PWCSH1 is set, and the subsequent measurement is not performed. However, if a timer restart
is also specified, the timer state changes to measurement start edge wait state.
●
Continuous measurement mode [H/L pulse-width measurement mode]
When the count end edge is input, the count end flag (EDIR) of PWCSH0/PWCSH1 is set, the timer count
result is transferred to PWC0/PWC1, and the timer may continue incrementing the count in a free-run state.
When the next count start edge is input, the timer is cleared to "0000
Notes:
When the count end edge is input and the timer enters a free-run state, the timer may overflow and the
OVIR flag may be set. In the H/L pulse-width measurement mode, do not use the OVIR flag to
measure the pulse-width time.
[All edge-to-edge pulse-width measurement mode, division period measurement mode, rising edge-to-
rising edge measurement mode, and falling edge-to-falling edge measurement mode]
When the count end edge (count start edge) is input, the count end flag (EDIR) of PWCSH0/PWCSH1
is set, the timer count result is transferred to PWC0/PWC1, the timer is cleared to "0000
count is restarted.
■ Measurement Result Data
Handling of the measurement result, timer value, and PWC0/PWC1 function varies with the single
measurement mode and continuous measurement mode as follows:
●
Single measurement mode
When PWC0/PWC1 is read during timer operation, the current timer value is read.
When PWC0/PWC1 is read after termination of measurement, the measurement results are read.
456
" and the pulse-width count is started.
H
" and the
H
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