Renesas H8S/2633 Series Hardware Manual page 690

Bits 2 to 0—Clock Select 2 to 0 (CKS2 to CKS0): These bits select whether the clock input to
TCNT is an internal or external clock.
Three internal clocks can be selected, all divided from the system clock (ø): ø/8, ø/64, and ø/8192.
The falling edge of the selected internal clock triggers the count.
When use of an external clock is selected, three types of count can be selected: at the rising edge,
the falling edge, and both rising and falling edges.
Some functions differ between channel 0 and channel 1.
Bit 2 Bit 1 Bit 0
CKS2 CKS1 CKS0
0 0 0
1
1 0
1
1 0 0
1
1 0
1
Note: * If the count input of channel 0 (channel 2) is the TCNT1 (TCNT3) overflow signal and that of
channel 1 (channel 3) is the TCNT0 (TCNT2) compare match signal, no incrementing clock
is generated. Do not use this setting.
636
Description
Clock input disabled
Internal clock, counted at falling edge of ø/8
Internal clock, counted at falling edge of ø/64
Internal clock, counted at falling edge of ø/8192
For channel 0: count at TCNT1 overflow signal*
For channel 1: count at TCNT0 compare match A*
For channel 2: count at TCNT3 overflow signal*
For channel 3: count at TCNT2 compare match A*
External clock, counted at rising edge
External clock, counted at falling edge
External clock, counted at both rising and falling edges
(Initial value)