NXP Semiconductors MKW01Z128, Reference Manual

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11.5.2 VLLS modes
For any wakeup from VLLS, recovery is always via a reset flow and
RCM_SRS[WAKEUP] is set indicating the low-leakage mode was active. State retention
data is lost and I/O will be restored after PMC_REGSC[ACKISO] has been written.
A VLLS exit event due to RESET pin assertion causes an exit via a system reset. State
retention data is lost and the I/O states immediately return to their reset state. The
RCM_SRS[WAKEUP] and RCM_SRS[PIN] bits are set and the system executes a reset
flow before CPU operation begins with a reset vector fetch.
11.5.3 Initialization
For an enabled peripheral wakeup input, the peripheral flag must be cleared by software
before entering LLS or VLLSx mode to avoid an immediate exit from the mode.
Flags associated with external input pins, filtered and unfiltered, must also be cleared by
software prior to entry to LLS or VLLSx mode.
After enabling an external pin filter or changing the source pin, wait at least five LPO
clock cycles before entering LLS or VLLSx mode to allow the filter to initialize.
NOTE
After recovering from a VLLS mode, user must restore chip
configuration before clearing PMC_REGSC[ACKISO]. In
particular, pin configuration for enabled LLWU wake-up pins
must be restored to avoid any LLWU flag from being falsely set
when PMC_REGSC[ACKISO] is cleared.
The signal selected as a wake-up source pin must be a digital
pin, as selected in the pin mux control.
Functional description
MKW01Z128 MCU Reference Manual, Rev. 3, 04/2016
222 Freescale Semiconductor, Inc.