Hitachi H8S/2633 Hardware Manual page 565

Table 13-5 Switching of Internal Clock and TCNT Operation
Timing of Switchover
by Means of CKS1
No. and CKS0 Bits
1 Switching from
low to low*
2 Switching from
low to high*
3 Switching from
high to low*
544
TCNT Clock Operation
Clock before
1
switchover
Clock after
switchover
TCNT clock
TCNT
Clock before
2
switchover
Clock after
switchover
TCNT clock
TCNT
Clock before
3
switchover
Clock after
switchover
TCNT clock
TCNT
N
CKS bit write
N N+1
CKS bit write
N N+1
CKS bit write
N+1
N+2
*4
N+2