Operations Of The Pulse Width Measurement Function - Fujitsu MB90480 Series Hardware Manual

25.5.2 Operations of the Pulse Width Measurement Function

With this function, the timer can be used to measure the time interval between any
input pulse events.
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Operations of the pulse width measurement function
After the start of the pulse width measurement function, counting does not start before the
specified measurement start edge is input. The timer is cleared to "0000
edge is detected, and counting up starts. Counting stops when a stop edge is detected. The
count value during this period is stored in the register as the pulse width. The end of
measurement is detected by an interrupt.
After measurement ends, the following operations are performed depending on the measurement
mode:
• In one-shot measurement mode: Operation is interrupted.
• In repeated measurement mode: The timer value is transferred to the buffer register and the
measurement is suspended until input of the next start edge.
Figure 25.5-2 shows the operation in one-shot measurement mode. Figure 25.5-3 shows the
operation in repeated measurement mode.
(one-shot measurement mode/"H" level pulse width measurement)
PWC input pulses
to be measured
Timer count value
FFFF
H
0000
H
Measurement
starts
Figure 25.5-2 Pulse width measurement operation
Timer clear
Timer
Timer stop
start
EDIR flag set (measurement end)
CHAPTER 25 PWC TIMER (ONLY MB90485 SERIES)
(Solid line indicates timer count value)
" whenever a start
H
Time
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