• The maximum frequencies of the system, bus, flash, and core are restricted. See the
Power Management details about which frequencies are supported.
• Mode protection must be set to allow VLP modes, that is, PMPROT[AVLP] is 1.
• PMCTRL[RUNM] is set to 10b to enter VLPR.
• Flash programming/erasing is not allowed.
NOTE
Do not change the clock frequency while in VLPR mode,
because the regulator is slow responding and cannot manage
fast load transitions. In addition, do not modify the clock source
in the MCG module, the module clock enables in the SIM, or
any clock divider registers.
To reenter Normal Run mode, clear RUNM. The PMSTAT register is a read-only status
register that can be used to determine when the system has completed an exit to RUN
mode. When PMSTAT=RUN, the system is in run regulation and the MCU can run at
full speed in any clock mode. If a higher execution frequency is desired, poll the
PMSTAT register until it is set to RUN when returning from VLPR mode.
Any reset always causes an exit from VLPR and returns the device to RUN mode after
the MCU exits its reset flow.
13.4.4 Wait modes
This device contains two different wait modes:
• Wait
• Very-Low Power Wait (VLPW)
13.4.4.1 WAIT mode
WAIT mode is entered when the ARM core enters the Sleep-Now or Sleep-On-Exit
modes while SLEEDEEP is cleared. The ARM CPU enters a low-power state in which it
is not clocked, but peripherals continue to be clocked provided they are enabled. Clock
gating to the peripheral is enabled via the SIM..
When an interrupt request occurs, the CPU exits WAIT mode and resumes processing in
RUN mode, beginning with the stacking operations leading to the interrupt service
routine.
A system reset will cause an exit from WAIT mode, returning the device to normal RUN
mode.
Functional description
KL02 Sub-Family Reference Manual, Rev. 2.1, July 2013
176
Freescale Semiconductor, Inc.