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11.4.2
Basic Functions
Counter Operation: When one of bits CST0 to CST5 is set to 1 in TSTR, the TCNT counter for
the corresponding channel starts counting. TCNT can operate as a free-running counter, periodic
counter, and so on.
• Example of count operation setting procedure
Figure 11-6 shows an example of the count operation setting procedure.
Operation selection
Select counter clock
Periodic counter
Select counter clearing source
Select output compare register
Set period
Start count operation
<Periodic counter>
Figure 11-6 Example of Counter Operation Setting Procedure
[1]
Free-running counter
[2]
[3]
[4]
[5]
Start count operation
<Free-running counter>
[1]
Select the counter
clock with bits
TPSC2 to TPSC0 in
TCR. At the same
time, select the
input clock edge
with bits CKEG1
and CKEG0 in TCR.
[2]
For periodic counter
operation, select the
TGR to be used as
the TCNT clearing
source with bits
CCLR2 to CCLR0 in
TCR.
[3]
Designate the TGR
selected in [2] as an
output compare
register by means of
TIOR.
[4]
Set the periodic
counter cycle in the
TGR selected in [2].
[5]
[5]
Set the CST bit in
TSTR to 1 to start
the counter
operation.
447
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