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Counter setup
Select counter clock
Type of counting?
Periodic counting
Select counter clear source
Select output compare
register function
Set period
Start counter
Free-running counting
Start counter
Periodic counter
Free-running counter
1
2
3
4
5
5
Yes
No
Figure 8-14 Counter Setup Procedure (Example)
1. Set bits TPSC2 to TPSC0 in TCR to select the counter clock source. If an external clock source
is selected, set bits CKEG1 and CKEG0 in TCR to select the desired edge(s) of the external
clock signal.
2. For periodic counting, set CCLR1 and CCLR0 in TCR to have TCNT cleared at GRA compare
match or GRB compare match.
3. Set TIOR to select the output compare function of GRA or GRB, whichever was selected in
step 2.
4. Write the count period in GRA or GRB, whichever was selected in step 2.
5. Set the STR bit to 1 in TSTR to start the timer counter.
