S12 Clock, Reset and Power Management Unit (S12CPMU)
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 7-34.
Figure 7-34. Enabling the External Oscillator
enable external oscillator by writing OSCE bit to one.
OSCE
crystal/resonator starts oscillating
EXTAL
UPOSC flag is set upon successful start of oscillation
UPOSC
OSCCLK
PLLSEL
select OSCCLK as Core/Bus Clock by writing PLLSEL to zero
based on OSCCLK
based on PLLCLK
Core
Clock
S12P-Family Reference Manual, Rev. 1.13
Freescale Semiconductor
241
FREESCALE [ Freescale ]
