Synchronous Operation - Hitachi H8S/2646 Hardware Manual

Hitachi 16-bit single-chip microcomputer h8s/2646 series
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10.4.3

Synchronous Operation

In synchronous operation, the values in a number of TCNT counters can be rewritten
simultaneously (synchronous presetting). Also, a number of TCNT counters can be cleared
simultaneously by making the appropriate setting in TCR (synchronous clearing).
Synchronous operation enables TGR to be incremented with respect to a single time base.
Channels 0 to 5 can all be designated for synchronous operation.
Example of Synchronous Operation Setting Procedure: Figure 10-14 shows an example of the
synchronous operation setting procedure.
Synchronous operation
selection
Set synchronous
operation
Synchronous presetting
Set TCNT
<Synchronous presetting>
Set to 1 the SYNC bits in TSYR corresponding to the channels to be designated for synchronous
[1]
operation.
When the TCNT counter of any of the channels designated for synchronous operation is
[2]
written to, the same value is simultaneously written to the other TCNT counters.
Use bits CCLR2 to CCLR0 in TCR to specify TCNT clearing by input capture/output compare,
[3]
etc.
Use bits CCLR2 to CCLR0 in TCR to designate synchronous clearing for the counter clearing
[4]
source.
Set to 1 the CST bits in TSTR for the relevant channels, to start the count operation.
[5]
Figure 10-14 Example of Synchronous Operation Setting Procedure
[1]
Synchronous clearing
[2]
Clearing
sourcegeneration
channel?
Yes
Select counter
clearing source
Start count
<Counter clearing>
No
Set synchronous
[3]
counter clearing
[5]
Start count
<Synchronous clearing>
[4]
[5]
345

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