Mitsubishi Electric M32170F3VFP, User Manual

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10
10-93 Ver.0.10
MULTIJUNCTION TIMERS
10.3 TOP (Output-related 16-bit Timer)
(2) Correction function of TOP delayed single-shot output mode
If you want to change the counter value during operation, write a value to the TOP correction
register, the value by which you want to be increased or reduced from the initial count set in the
counter. To add, write the value you want to add to the correction register directly as is; to
subtract, write the two's complement of the value you want to subtract to the correction register.
Correction of the counter is performed synchronously with a clock period next to the one in which
the correction value was written to the TOP correction register. In this case, one down-count in
the clock period during which the correction was performed is canceled. Therefore, note that the
counter value actually is corrected by (correction register value + 1).
For example, if the initial counter value is 7 and you write a value 3 to the correction register when
the counter has counted down to 3, then the counter underflows after a total of 12 counts after
reload.
Figure 10.3.17 Example of Counting in TOP Delayed Single-shot Output Mode When Count
is Corrected
When writing to the correction register, be careful not to cause the counter to overflow. Even
when the counter overflows due to correction of counts, no interrupt is generated for the
occurrence of overflow.
Enable = "H"
Reload
register
(7)
6
5
4
3
2
1
0
1 2 3 4 5 6 7 8 9 10 11 12
6
5
4
3
H'FFFF
7
Counter
3
Correction
register
+
3
Interrupt
Underflow
Count value after reload =(7+1)+(3+1)=12
(Note 1)
0
Count clock
Note 1: What you actually see in the cycle immediately after reload is the previous counter value,
and not 7.
Note 2: This diagram does not show detail timing information.