For internal module wakeup operation, the WUMEx bit enables the associated module asa wakeup source.15.4.1 LLS modeWakeup events triggered from either an external pin input or an internal module inputresult in a CPU interrupt flow to begin user code execution.15.4.2 VLLS modesIn the case of a wakeup due to external pin or internal module wakeup, recovery isalways via a reset flow and the RCM_SRS[WAKEUP] is set indicating the low-leakagemode was active. State retention data is lost and I/O will be restored afterPMC_REGSC[ACKISO] has been written.15.4.3 InitializationFor an enabled peripheral wakeup input, the peripheral flag must be cleared by softwarebefore 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 bysoftware prior to entry to LLS or VLLSx mode.After enabling an external pin filter or changing the source pin, wait at least 5 LPO clockcycles before entering LLS or VLLSx mode to allow the filter to initialize.NOTEAfter recovering from a VLLS mode, user must restore chipconfiguration before clearing ACKISO. In particular, pinconfiguration for enabled LLWU wakeup pins must be restoredto avoid any LLWU flag from being falsely set when ACKISOis cleared.The signal selected as a wakeup source pin must be a digitalpin, as selected in the pin mux control.Chapter 15 Low-Leakage Wakeup Unit (LLWU)KL04 Sub-Family Reference Manual, Rev. 3.1, November 2012Freescale Semiconductor, Inc. 231
