2. Requests are made to all non-CPU bus masters to enter Stop mode.
3. After all masters have acknowledged they are ready to enter Stop mode, requests are
made to all bus slaves to enter Stop mode.
4. After all slaves have acknowledged they are ready to enter Stop mode, all system and
bus clocks are gated off.
5. Clock generators are disabled in the MCG.
6. The on-chip regulator in the PMC and internal power switches are configured to
meet the power consumption goals for the targeted low-power mode.
15.4.2.2 Stop mode exit sequence
Exit from a low-power stop mode is initiated either by a reset or an interrupt event. The
following sequence then executes to restore the system to a run mode (RUN or VLPR):
1. The on-chip regulator in the PMC and internal power switches are restored.
2. Clock generators are enabled in the MCG.
3. System and bus clocks are enabled to all masters and slaves.
4. The CPU clock is enabled and the CPU begins servicing the reset or interrupt that
initiated the exit from the low-power stop mode.
15.4.2.3
Aborted stop mode entry
If an interrupt occurs during a stop entry sequence, the SMC can abort the transition early
and return to RUN mode without completely entering the stop mode. An aborted entry is
possible only if the interrupt occurs before the PMC begins the transition to stop mode
regulation. After this point, the interrupt is ignored until the PMC has completed its
transition to stop mode regulation. When an aborted stop mode entry sequence occurs,
SMC_PMCTRL[STOPA] is set to 1.
15.4.2.4
Transition to wait modes
For wait modes (WAIT and VLPW), the CPU clock is gated off while all other clocking
continues, as in RUN and VLPR mode operation. Some modules that support stop-in-
wait functionality have their clocks disabled in these configurations.
Chapter 15 System Mode Controller (SMC)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 363
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