Hitachi H8/329 Series Hardware Manual page 151

Table 6-5. Effect of Changing Internal Clock Sources (cont.)
No. Description
High → Low:
CKS1 and CKS0 are
3 rewritten while old
clock source is High and
new clock source is Low.
High → High:
CKS1 and CKS0 are
4 rewritten while both
clock sources are High.
Note: * The switching of clock sources is regarded as a falling edge that increments the FRC.
Timing chart
Old clock
source
New clock
source
FRC clock
pulse
FRC N
Old clock
source
New clock
source
FRC clock
pulse
N
FRC
142
*
N + 1 N + 2
CKS rewrite
N + 1 N + 2
CKS rewrite