4.4 Low-Power Modes

The various low-power modes (Backup, Wait and Sleep modes) are described below. Note that the SLCDC can be used in all low-power modes.

The Wait For Event instruction (WFE) of the Cortex-M4 core can be used to enter any of the low-power modes, however this may add complexity to the design of application state machines. This is due to the fact that the WFE instruction is associated with an event flag of the Cortex core that cannot be managed by the software application. The event flag can be set by interrupts, a debug event or an event signal from another processor. When an event occurs just before WFE execution, the processor takes it into account and does not enter Low-power mode. Microchip has made provision to avoid using the WFE instruction. The workarounds to ease application design, including the use of the WFE instruction, are given in the following descriptions of the Low-Power mode sequences.