18.7.1 Sleep

When a device enters Sleep mode, the system clock used by the core processor and peripherals is halted. To use run in Sleep mode, a clock source other than the system clock must be selected and the SLPEN bit (UxCON[31]) is set. Clock sources are device-specific (see Clocking and Baud Rate Configuration for details). This allows the UART to request the selected clock source and keep it active. The UART has the ability to continue transmitting the contents of UxTXB, receiving data and storing them in UxRXB.

The UART can also wake the processor from Sleep mode (when SPLEN = 0) on the detection of an incoming byte, including Break and Sync characters used for auto-baud. To enable the wake feature, set the WUE bit (UxCON[12]). When a wake from Sleep occurs, the WUIF (UxUIR[7]) bit is set and an event interrupt is generated, effectively waking the processor. If auto-baud is desired on wake, set the ABDEN bit before executing a SLEEP command.