HD6475328-CP10 Datasheet, PDF (221/459 Pages) Hitachi Semiconductor – original Hitachi CMOS microcomputer unit (MCU)

Table 10-5 Effect of Changing Internal Clock Sources
No. Description
1
Low → Low:
CKS1 and CKS0 are
rewritten while both
clock sources are Low.
Timing Chart
Old clock
source
New clock
source
FRC clock
pulse
FRC
N
N+1
2
Low → High:
CKS1 and CKS0 are
rewritten while old
Old clock
source
clock source is Low and
new clock source is High.
New clock
source
CKS rewrite
FRC clock
pulse
FRC
N
N+1
N+2
3
High → Low:
CKS1 and CKS0 are
rewritten while old
Old clock
source
clock source is High and
new clock source is Low.
New clock
source
*
FRC clock
pulse
FRC
N
N+1
N+2
CKS rewrite
∗ The switching of clock sources is regarded as a falling edge that increments the FRC.
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