Hitachi H8S/2646 Hardware Manual page 338

Bits 4 and 3—Clock Edge 1 and 0 (CKEG1, CKEG0): These bits select the input clock edge.
When the input clock is counted using both edges, the input clock period is halved (e.g. ø/4 both
edges = ø/2 rising edge). If phase counting mode is used on channels 1, 2, 4, and 5, this setting is
ignored and the phase counting mode setting has priority.
Bit 4 Bit 3
CKEG1 CKEG0
0 0
1
1 —
Note: Internal clock edge selection is valid when the input clock is ø/4 or slower. This setting is
ignored if the input clock is ø/1, or when overflow/underflow of another channel is selected.
Bits 2 to 0—Time Prescaler 2 to 0 (TPSC2 to TPSC0): These bits select the TCNT counter
clock. The clock source can be selected independently for each channel. Table 10-4 shows the
clock sources that can be set for each channel.
Table 10-4 TPU Clock Sources
Channel ø/1 ø/4 ø/16 ø/64 ø/256 ø/1024 ø/4096
0
1
2
3
4
5
Legend
: Setting
Blank: No setting
306
Description
Count at rising edge
Count at falling edge
Count at both edges
Internal Clock External Clock
TCLKA TCLKB TCLKC TCLKD Channel
(Initial value)
Overflow/
Underflow
on Another