Chapter 7 Mode Entry Module (MC_ME)
MPC5602P Microcontroller Reference Manual, Rev. 4
Freescale Semiconductor
169
7.4.3.14
Clock Sources (with no Dependencies) Switch-Off
Based on the device mode and the <clock source>ON bits of the ME_<mode>_MC registers, if a given
clock source is to be switched off and no other clock source needs it to be on, the MC_ME requests the
clock source to power down and updates its availability status bit S_<clock source> of the ME_GS register
to ‘0’. The following clock sources switched off at this step:
•
the 4 MHz crystal oscillator
•
the system PLL
This step is executed only after the
process has completed.
7.4.3.15
Clock Sources (with Dependencies) Switch-Off
Based on the device mode and the <clock source>ON bits of the ME_<mode>_MC registers, if a given
clock source is to be switched off and all clock sources which need this clock source to be on have been
switched off, the MC_ME requests the clock source to power down and updates its availability status bit
S_<clock source> of the ME_GS register to ‘0’. The following clock sources switched off at this step:
•
the 16 MHz internal RC oscillator
This step is executed only after
•
the
process has completed in order not to lose the current system clock
during mode transition
•
the
Clock Sources (with no Dependencies) Switch-Off
process has completed in order to, for
example, prevent unwanted lock transitions
7.4.3.16
Flash Switch-Off
Based on the CFLAON and DFLAON bit fields of the ME_<current mode>_MC and
ME_<target mode>_MC registers, if any of the flashes is to be put in its low-power or power-down mode,
the MC_ME requests the flash to enter the corresponding power mode and waits for the flash to
acknowledge. The exact power mode status of the flashes is updated in the S_CFLA and S_DFLA bit
fields of the ME_GS register. This step is executed only when the
Processor and System Memory Clock
7.4.3.17
Current Mode Update
The current mode status bit field S_CURRENT_MODE of the ME_GS register is updated with the target
mode bit field TARGET_MODE of the ME_MCTL register when:
•
all the updated status bits in the ME_GS register match the configuration specified in the
ME_<target mode>_MC register
•
power sequences are done
•
clock disable/enable process is finished
•
processor low-power mode (halt/stop) entry and exit processes are finished