FUJITSU MB91460 SERIES FR60 - Manual (Page 870)

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Chapter 41 Up/Down Counter
5.Operation
5.7 Reload Timing
The next time when Up/Down Counter counts down below “0000”, an underflow occurs (an interrupt request is
made) and then reloading is performed.
Note: If clear and reload operations occur at the same time, clear takes precedence.
5.8 Writing a Value to Counter
(1) Counting of Up/Down Counter is disabled.
(2) A value is written to PCR.
(3) “1” is written to the count write bit CTUT.
(4) A value is transferred from the reload/compare register RCR to Up/Down Counter.
Countdown
Reload timing
0066
H
Underflow
0001
H
0066
H
0064
H
0000
H
0065
H
Count value
Compare value
RCR
Up/Down Counter
CSTR
CTUT (3)
(1)
(4)
(2)
XXH 67 H
67 H
(3)
(1)
(4)
(2)
H
67