Fujitsu MB91260B Series Hardware Manual page 212

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Measurement mode and count operation
The measurement mode can be selected from five types depending on the place where the input pulse is
measured. The cycle measurement mode is also prepared to arbitrarily divide the input pulse for high-
precision measurement of higher frequency pulse width. They are described below.
Measurement Mode MOD2 MOD1 MOD0
Pulse width
measurement between
all edges
Measurement at cycle
of dividing frequency
Rising edge-to-edge
cycle measurement
"H" pulse width
measurement
"L" pulse width
measurement
Rising edge-to-edge
cycle measurement
CHAPTER 10 PWC (Pulse Width Count: Pulse Width Measurement)
0 0 0
The width between the edges continuously input is measured.
Count (measurement) beginning: When edge is detected
Count (measurement) end: When edge is detected
0 0 1
Only the divide ratio of frequency selected by divide ratio frequency
setting register PDIVR0 or PDIVR1 divides the input pulse. And, the
cycle is measured.
Count (measurement) start: At rising edge detection (directly after start)
Count (measurement) end: when one cycle ends after it is divided
0 1 0
Measure a cycle between rising edges.
Count (measurement) start: At rising edge detection
Count (measurement) end: At rising edge detection
0 1 1
The width at H period is measured.
Count (measurement) start: At rising edge detection
Count (measurement) end: At falling edge detection
1 0 0
The width at L period is measured.
Count (measurement) start: At falling edge detection
Count (measurement) end: At rising edge detection
1 0 1
Measure a cycle between falling edges.
Count (measurement) start: At falling edge detection
Count (measurement) end: At falling edge detection
Measurement Details (W: Pulse Width to Be Measured)
W
W
↑ Count start
↓ Count stop
↓ Start
W
↑ Count start
↓ Count stop
↓ Start
(Example of
divide-by-4)
W
W
↑ Count start ↑ Count stop
↑ Stop
↑ Start
↑ Start
W
↑ Count start
↓ Count stop
W
↓ Count start
↑ Count stop
W
W
↓ Count start
↓ Count stop
↓ Start
W
↑ Stop
↑ Start
↓
Stop
W
W
↓
Stop
W
↑
Stop
W
↑ ↑
Start Stop
W
↓ ↑
Start Stop
W
↓ Stop
↓ Start
↓
Stop
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