(4) Incrementation Caused by Changing of Internal Clock Source: When an internal clock
source is changed, the changeover may cause the FRC to increment. This depends on the time at
which the clock select bits (CKS1 and CKS0) are rewritten, as shown in table 6-5.
The pulse that increments the FRC is generated at the falling edge of the internal clock source. If
clock sources are changed when the old source is High and the new source is Low, as in case No. 3
in table 6-5, the changeover generates a falling edge that triggers the FRC increment clock pulse.
Switching between an internal and external clock source can also cause the FRC to increment.
Table 6-5. Effect of Changing Internal Clock Sources
No.
Description
Timing chart
Low
→
Low:
CKS1 and CKS0 are
1
rewritten while both
clock sources are Low.
Low
→
High:
CKS1 and CKS0 are
2
rewritten while old
clock source is Low and
new clock source is High.
Old clock
source
New clock
source
FRC clock
pulse
FRC
CKS rewrite
N
N + 1
Old clock
source
New clock
source
FRC clock
pulse
FRC
CKS rewrite
N
N + 1
N + 2
141
Содержание H8/326 Series
Страница 67: ...58 ...
Страница 121: ...112 ...
Страница 274: ... 3 Clock Settling Timing Ø VCC RES STBY tOSC1 tOSC1 Figure 14 8 Clock Setting Timing 265 ...
Страница 279: ...270 ...