MC9S08DN60 Datasheet, PDF (152/354 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 8 Multi-Purpose Clock Generator (S08MCGV1)
START
IN BLPI MODE
MCGC2 = $00
OPTIONAL: _NO
CHECK LOCK
= 1?
YES
MCGC2 = $36
CHECK
NO
OSCINIT = 1 ?
YES
MCGC1 = $38
CHECK
NO
IREFST = 0?
YES
OPTIONAL: _NO
CHECK LOCK
= 1?
YES
CHECK
NO
CLKST = %00?
YES
CONTINUE
IN FEE MODE
Figure 8-11. Flowchart of BLPI to FEE Mode Transition using a 4 MHz crystal
8.5.2.4 Example # 4: Moving from FEI to PEE Mode: External Crystal = 8 MHz,
Bus Frequency = 8 MHz
In this example, the MCG will move through the proper operational modes from FEI to PEE mode until
the 8 MHz crystal reference frequency is set to achieve a bus frequency of 8 MHz.
This example is similar to example number one except that in this case the frequency of the external crystal
is 8 MHz instead of 4 MHz. Special consideration must be taken with this case since there is a period of
time along the way from FEI mode to PEE mode where the FLL operates based on a reference clock with
a frequency that is greater than the maximum allowed for the FLL. This occurs because with an 8 MHz
MC9S08DN60 Series Data Sheet, Rev 2
152
Freescale Semiconductor