Datasheet

Section 12 Timer F
Rev. 2.00 Jul. 04, 2007 Page 244 of 692
REJ09B0309-0200
12.4.2 TCF Increment Timing
(1) Internal Clock Operation
TCF is incremented by internal clock or external event input. Bits CKSH2 to CKSH0 or CKSL2 to
CKSL0 in TCRF select one of internal clock sources (φ/32, φ/16, φ/4, or φ
W
/4) created by dividing
the system clock (φ or φ
W
).
N
N+1
N-1
φ
Count input
clock (φ/4)
TCF
Figure 12.2 Count Timing for Internal Clock Operation
(2) External Event Operation
When the CKSL2 bit in TCRF is cleared to 0, external event input is selected. The counter is
incremented at both rising and falling edges of external events. The TMIFEG bit in IEGR selects
which edge of an external event is used for counting. The external event pulse width requires
clock time longer than 2 system clocks (φ), or 2 subclocks (φ
SUB
), depending on the operating
mode. Note that an external event does not operate correctly with the lower pulse width.
TCF
NN-1
TMIF
(TMIFEG = 1)
φ
Count input
clock
Figure 12.3 Count Timing for External Event Operation