Freescale Semiconductor MC9S12XDP512 The sequence for clock quality check is shown in Figure 5-20.

Chapter 5 Clocks and Reset Generator (S12CRGV6)
MC9S12XDP512 Data Sheet, Rev. 2.11
294 Freescale Semiconductor
A number greater equal than 4096 rising OSCCLK edges within a check window is called osc ok. Note that
osc ok immediately terminates the current check window. See Figure 5-19 as an example.
Figure 5-19. Check Window Example
The sequence for clock quality check is shown in Figure 5-20.
Figure 5-20. Sequence for Clock Quality Check
12 49999 50000
VCO
Clock
check window
12345
4095
4096
3
OSCCLK
osc ok
check window
osc ok
?
SCM
active? Switch to OSCCLK
Exit SCM
Clock OK
num = 50
num > 0
?
num=num–1
yes
no
yes
SCME=1
?
no
Enter SCM
SCM
active?
yes
Clock Monitor Reset
no
yes
no
num = 0
yes
no
POR
exit full stop
CM fail
LVR
yes
no
?
FSTWKP = 0
no
num = 0 Enter SCM
yes
SCME = 1 &
FSTWKP = 1
?