mc9s12xs128 Freescale Semiconductor, Inc, mc9s12xs128 Datasheet - Page 50

• Manufacturer Part Number: mc9s12xs128
• Description: Hcs12 Microcontrollers 16-bit Automotive Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Device Overview S12XS Family
1.4.1.2
This mode is used for debugging single-chip operation, boot-strapping, or security related operations. The
background debug module BDM is active in this mode. The CPU executes a monitor program located in
an on-chip ROM. BDM firmware waits for additional serial commands through the BKGD pin.
1.4.2
The MCU features two main low-power modes. Consult the respective section for module specific
behavior in system stop, system pseudo stop, and system wait mode. An important source of information
about the clock system is the Clock and Reset Generator section (CRG).
1.4.2.1
The system stop modes are entered if the CPU executes the STOP instruction unless an NVM command
is active. Depending on the state of the PSTP bit in the CLKSEL register the MCU goes into pseudo stop
mode or full stop mode. Please refer to CRG section. Asserting RESET, XIRQ, IRQ or any other interrupt
that is not masked exits system stop modes. System stop modes can be exited by CPU activity, depending
on the configuration of the interrupt request.
If the CPU executes the STOP instruction whilst an NVM command is being processed, then the system
clocks continue running until NVM activity is completed. If a non-masked interrupt occurs within this time
then the system does not effectively enter stop mode although the STOP instruction has been executed.
1.4.2.2
The oscillator is stopped in this mode. By default all clocks are switched off and all counters and dividers
remain frozen. The Autonomous Periodic Interrupt (API) and ATD module may be enabled to self wake
the device. A Fast wake up mode is available to allow the device to wake from Full Stop mode immediately
on the PLL internal clock without starting the oscillator clock.
1.4.2.3
In this mode the system clocks are stopped but the oscillator is still running and the real time interrupt
(RTI) and watchdog (COP), API and ATD modules may be enabled. Other peripherals are turned off. This
mode consumes more current than system stop mode but, as the oscillator continues to run, the full speed
wake up time from this mode is significantly shorter.
1.4.2.4
This mode is entered when the CPU executes the WAI instruction. In this mode the CPU will not execute
instructions. The internal CPU clock is switched off. All peripherals can be active in system wait mode.
For further power consumption the peripherals can individually turn off their local clocks. Asserting
RESET, XIRQ, IRQ or any other interrupt that is not masked ends system wait mode.
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Power Modes
Special Single-Chip Mode
System Stop Modes
Full Stop Mode
Pseudo Stop Mode
Wait Mode
S12XS Family Reference Manual, Rev. 1.10
Freescale Semiconductor