MC9S12P128 Datasheet, PDF (235/564 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

S12 Clock, Reset and Power Management Unit (S12CPMU) Block Description
Disable PLL Lock interrupt (LOCKIE=0) and Oscillator status change interrupt (OSCIE=0) before going
into Full Stop Mode.
Figure 7-34. Stop Mode using Oscillator Clock as Bus Clock
wakeup
CPU execution
Core
Clock
PLLCLK
STOP instruction
t_{STP_REC}
interrupt continue execution
t_lock
OSCCLK
UPOSC
PLLSEL
select OSCCLK as Core/Bus Clock by writing PLLSEL to “0”
automatically set when going into Full Stop Mode
7.4.5 External Oscillator
7.4.5.1 Enabling the External Oscillator
An example of how to use the Oscillator as Bus Clock is shown in Figure 7-35.
S12P-Family Reference Manual, Rev. 1.12
Freescale Semiconductor
235