Before configuring the asynchronous partial wakeup function of a peripheral, check that the PIDx bit in PMC_PCSR is set. This ensures that the peripheral clock is enabled.
The steps to enable the asynchronous partial wakeup function of a peripheral are the following:
If an activity has started during the enable phase, the asynchronous partial wakeup function must be immediately disabled by writing a ‘1’ to the PIDx bit in the PMC SleepWalking Disable register (PMC_SLPWK_DR). Wait for the end of peripheral activity before reinitializing the procedure.