S12 Clock, Reset and Power Management Unit (S12CPMU)
MC9S12G Family Reference Manual Rev.1.27
356 NXP Semiconductors
— The Bus Clock is based on the Oscillator Clock (OSCCLK).
— The PLLCLK is always on to qualify the external oscillator clock. Therefore it is necessary to
make sure a valid PLL configuration is used for the selected oscillator frequency.
— This mode can be entered from default mode PEI by performing the following steps:
– Make sure the PLL configuration is valid for the selected oscillator frequency.
– Enable the external oscillator (OSCE bit)
– Wait for oscillator to start up (UPOSC=1)
– Select the Oscillator Clock (OSCCLK) as Bus Clock (PLLSEL=0).
— The PLLCLK is on and used to qualify the external oscillator clock.
10.1.2.2 Wait Mode
For S12CPMU Wait Mode is the same as Run Mode.
10.1.2.3 Stop Mode
This mode is entered by executing the CPU STOP instruction.
The voltage regulator is in Reduced Power Mode (RPM).
The API is available.
The Phase Locked Loop (PLL) is off.
The Internal Reference Clock (IRC1M) is off.
Core Clock, Bus Clock and BDM Clock are stopped.
Depending on the setting of the PSTP and the OSCE bit, Stop Mode can be differentiated between Full
Stop Mode (PSTP = 0 or OSCE=0) and Pseudo Stop Mode (PSTP = 1 and OSCE=1). In addition, the
behavior of the COP in each mode will change based on the clocking method selected by
COPOSCSEL[1:0].
• Full Stop Mode (PSTP = 0 or OSCE=0)
External oscillator (XOSCLCP) is disabled.
— If COPOSCSEL1=0:
The COP and RTI counters halt during Full Stop Mode.
After wake-up from Full Stop Mode the Core Clock and Bus Clock are running on PLLCLK
(PLLSEL=1). COP and RTI are running on IRCCLK (COPOSCSEL0=0, RTIOSCSEL=0).
— If COPOSCSEL1=1:
During Full Stop Mode the COP is running on ACLK (trimmable internal RC-Oscillator clock)
and the RTI counter halts.
After wake-up from Full Stop Mode the Core Clock and Bus Clock are running on PLLCLK
(PLLSEL=1). The COP runs on ACLK and RTI is running on IRCCLK (COPOSCSEL0=0,
RTIOSCSEL=0).
To Next Page
Loading...
