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10.5
Operation
10.5.1
Basic Functions
Each channel has a TCNT and TGR. TCNT performs up-counting, and is also capable of free-
running operation, synchronous counting, and external event counting. Each TGR can be used as
an input capture register or output compare register.
(1)
Counter Operation
When one of bits CST0 to CST2 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.
(a)
Example of count operation setting procedure
Figure 10.6 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 10.6 Example of Counter Operation Setting Procedure
[1]
Free-running counter
[2]
[3]
[4]
[5]
Start count operation
<Free-running counter>
Section 10 16-Bit Timer Pulse Unit (TPU)
[1]
Select the counter clock with bits
TPSC2 to TPSC0 inTCR.
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.
Designate the TGR selected in [2]
[3]
as an output compare register by
means of TIOR.
[4]
Set the periodic counter cycle in
the TGR selected in [2].
[5]
Set the CST bit in TSTR to 1 to
start the counter operation.
Rev. 1.00 May 09, 2008 Page 253 of 954
REJ09B0462-0100
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