S9S12GN32F0MLC Datasheet, PDF (377/1292 Pages) Freescale Semiconductor, Inc – MC9S12G Family Reference Manual and Data Sheet

S12 Clock, Reset and Power Management Unit (S12CPMU)
Table 10-5. CPMUCLKS Descriptions
Field
Description
7
PLLSEL
6
PSTP
4
COP
OSCSEL1
3
PRE
2
PCE
PLL Select Bit
This bit selects the PLLCLK as source of the System Clocks (Core Clock and Bus Clock).
PLLSEL can only be set to 0, if UPOSC=1.
UPOSC= 0 sets the PLLSEL bit.
Entering Full Stop Mode sets the PLLSEL bit.
0 System clocks are derived from OSCCLK if oscillator is up (UPOSC=1, f_bus = f_osc / 2.
1 System clocks are derived from PLLCLK, f_bus = f_PLL / 2.
Pseudo Stop Bit
This bit controls the functionality of the oscillator during Stop Mode.
0 Oscillator is disabled in Stop Mode (Full Stop Mode).
1 Oscillator continues to run in Stop Mode (Pseudo Stop Mode), option to run RTI and COP.
Note: Pseudo Stop Mode allows for faster STOP recovery and reduces the mechanical stress and aging of the
resonator in case of frequent STOP conditions at the expense of a slightly increased power consumption.
Note: When starting up the external oscillator (either by programming OSCE bit to 1 or on exit from Full Stop
Mode with OSCE bit is already 1) the software must wait for a minimum time equivalent to the startup-time
of the external oscillator t_UPOSC before entering Pseudo Stop Mode.
COP Clock Select 1 — COPOSCSEL0 and COPOSCSEL1 combined determine the clock source to the COP
(see also Table 10-6).
If COPOSCSEL1 = 1, COPOSCSEL0 has no effect regarding clock select and changing the COPOSCSEL0 bit
does not re-start the COP time-out period.
COPOSCSEL1 selects the clock source to the COP to be either ACLK (derived from trimmable internal
RC-Oscillator) or clock selected via COPOSCSEL0 (IRCCLK or OSCCLK).
Changing the COPOSCSEL1 bit re-starts the COP time-out period.
COPOSCSEL1 can be set independent from value of UPOSC.
UPOSC= 0 does not clear the COPOSCSEL1 bit.
0 COP clock source defined by COPOSCSEL0
1 COP clock source is ACLK derived from a trimmable internal RC-Oscillator
RTI Enable During Pseudo Stop Bit — PRE enables the RTI during Pseudo Stop Mode.
0 RTI stops running during Pseudo Stop Mode.
1 RTI continues running during Pseudo Stop Mode if RTIOSCSEL=1.
Note: If PRE=0 or RTIOSCSEL=0 then the RTI will go static while Stop Mode is active. The RTI counter will not
be reset.
COP Enable During Pseudo Stop Bit — PCE enables the COP during Pseudo Stop Mode.
0 COP stops running during Pseudo Stop Mode if: COPOSCSEL1=0 and COPOSCSEL0=0
1 COP continues running during Pseudo Stop Mode if: PSTP=1, COPOSCSEL1=0 and COPOSCSEL0=1
Note: If PCE=0 or COPOSCSEL0=0 while COPOSCSEL1=0 then the COP is static during Stop Mode being
active. The COP counter will not be reset.
MC9S12G Family Reference Manual, Rev.1.23
Freescale Semiconductor
379