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Section 9 16-Bit Timer
φ
External
clock input
TCNT input
TCNT
Figure 9.16 Count Timing for External Clock Sources (when Both Edges are Detected)
Waveform Output by Compare Match: In 16-bit timer channels 0, 1 compare match A or B can
cause the output at the TIOCA or TIOCB pin to go to 0, go to 1, or toggle. In channel 2 the output
can only go to 0 or go to 1.
• Sample setup procedure for waveform output by compare match
Figure 9.17 shows the timing for detection of both rising and falling edges.
Output setup
Select waveform
output mode
Set output timing
Start counter
Waveform output
Figure 9.17 Setup Procedure for Waveform Output by Compare Match (Example)
• Examples of waveform output
Figure 9.18 shows examples of 0 and 1 output. TCNT operates as a free-running counter, 0
output is selected for compare match A, and 1 output is selected for compare match B. When
the pin is already at the selected output level, the pin level does not change.
Rev. 4.00 Jan 26, 2006 page 366 of 938
REJ09B0276-0400
N − 1
1.
Select the compare match output mode (0, 1, or
toggle) in TIOR. When a waveform output mode
is selected, the pin switches from its generic input/
output function to the output compare function
(TIOCA or TIOCB). An output compare pin outputs
1
the value set in TOLR until the first compare match
occurs.
2
2.
Set a value in GRA or GRB to designate the
compare match timing.
3
3.
Set the STR bit to 1 in TSTR to start the timer
counter.
N
N + 1
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