HD6413007F20 Datasheet, PDF (398/798 Pages) Renesas Technology Corp – Hardware Manual Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Series

10. 8-Bit Timers
10.4 Operation
10.4.1 8TCNT Count Timing
8TCNT is incremented by input clock pulses (either internal or external).
Internal Clock: Three different internal clock signals (φ/8, φ/64, or φ/8192) divided from the
system clock (φ) can be selected by setting bits CKS2 to CKS0 in 8TCR. Figure 10.8 shows the
count timing.
φ
Internal clock
8TCNT input clock
8TCNT
N–1
N
N+1
Figure 10.8 Count Timing for Internal Clock Input
Note: Even when the same internal clock is selected for both the 16- and 8-bit timers, they do
not operate in the same manner because the count-up edge differs.
External Clock: Three incrementation methods can be selected by setting bits CKS2 to CKS0 in
8TCR: on the rising edge, the falling edge, and both rising and falling edges.
The pulse width of the external clock signal must be at least 1.5 serial clocks when a single edge is
selected, and at least 2.5 system clocks when both edges are selected. Shorter pulses will not be
counted correctly.
Rev.5.00 Sep. 12, 2007 Page 368 of 764
REJ09B0396-0500