MC9S08QE16CLC Datasheet, PDF (186/350 Pages) Freescale Semiconductor, Inc – Low-power wireless applications, Gas, water and heater meters

Internal Clock Generator (S08ICGV4)
Bits 11:0 FLT
No need for user initialization
ICGTRM = $xx
Bits 7:0 TRIM Only need to write when trimming internal oscillator; not used when external 
crystal is clock source
Figure 10-14 shows flow charts for three conditions requiring ICG initialization.
RESET
INITIALIZE ICG
ICGC1 = $38
ICGC2 = $00
CHECK
FLL LOCK STATUS. ^NO
LOCK = 1?
YES
QUICK RECOVERY FROM STOP
RECOVERY FROM STOP
OSCSTEN = 1
CHECK
FLL LOCK STATUS. ^NO
LOCK = 1?
YES
CONTINUE
MINIMUM CURRENT DRAW IN STOP
RECOVERY FROM STOP
OSCSTEN = 0
CHECK
FLL LOCK STATUS. ^NO
LOCK = 1?
YES
CONTINUE
CONTINUE
NOTE: THIS WILL REQUIRE THE OSCILLATOR TO START AND
STABILIZE. ACTUAL TIME IS DEPENDENT ON CRYSTAL /RESONATOR
AND EXTERNAL CIRCUITRY.
Figure 10-14. ICG Initialization for FEE in Example #1
MC9S08AC60 Series Data Sheet, Rev. 3
186
Freescale Semiconductor