Hardware manual

Rev. 3.0, 09/98, page 170 of 361
N
N - 1
N + 1
External clock
source
TCNT clock
pulse
Ø
TCNT
Figure 8.3 Count Timing for External Clock Input
8.3.2 Compare Match Timing
(1) Setting of Compare-Match Flags A and B (CMFA and CMFB): The compare-match flags
are set to “1” by an internal compare-match signal generated when the timer count matches the
time constant in TCNT or TCOR. The compare-match signal is generated at the last state in
which the match is true, just before the timer counter increments to a new value.
Accordingly, when the timer count matches one of the time constants, the compare-match signal is
not generated until the next period of the clock source. Figure 8.4 shows the timing of the setting
of the compare-match flags.
N
N
N + 1
TCNT
Ø
TCOR
Internal
compare-match
signal
CMF
Figure 8.4 Setting of Compare-Match Flags