2.5.5.1.2 Wait for Event

The wait for event instruction, WFE, causes entry to sleep mode dependent on the value of a one-bit event register. When the processor executes a WFE instruction, it checks the value of the event register:

0: The processor stops executing instructions and enters Sleep mode.

1: The processor clears the register to 0 and continues executing instructions without entering Sleep mode.

For more information, see 2.6.10.12 WFI.

If the event register is 1, this indicate that the processor must not enter Sleep mode on execution of a WFE instruction. Typically, this is because an external event signal is asserted, or a processor in the system has executed an SEV instruction, see 2.6.10.9 SEV. Software cannot access this register directly.