MKL04Z32VFK4 Datasheet, PDF (231/658 Pages) Freescale Semiconductor, Inc – KL04 Sub-Family Reference Manual

Chapter 15 Low-Leakage Wakeup Unit (LLWU)
For internal module wakeup operation, the WUMEx bit enables the associated module as
a wakeup source.
15.4.1 LLS mode
Wakeup events triggered from either an external pin input or an internal module input
result in a CPU interrupt flow to begin user code execution.
15.4.2 VLLS modes
In the case of a wakeup due to external pin or internal module wakeup, recovery is
always via a reset flow and the 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.
15.4.3 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 5 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 ACKISO. In particular, pin
configuration for enabled LLWU wakeup pins must be restored
to avoid any LLWU flag from being falsely set when ACKISO
is cleared.
The signal selected as a wakeup source pin must be a digital
pin, as selected in the pin mux control.
KL04 Sub-Family Reference Manual, Rev. 3.1, November 2012
Freescale Semiconductor, Inc.
231