In System OFF, core system functionality is powered down and ongoing tasks are terminated. SRAM is not retained. Network registration is retained, and the module wakes from a defined set of sources.
Wake-up sources from System OFF:
- UART1 incoming data, if UART1 baud rate is configured to 9600 bps or lower before entering sleep.
- USB VBUS detect, wake when USB power is presented.
- POWERKEY signal pulled low.
- Internal paging timer, modem-internal wake on the next configured PSM or eDRX paging occasion.
- SIM hot-swap detect, wake when SIM presence transitions on a slot configured for detection.
Note: The System OFF configuration set by AT%SYSOFF=1 survives nRESET and a POWERKEY power
cycle. After a reset the module returns to System OFF rather than to normal operation. Disable
System OFF with AT%SYSOFF=0 before changing the UART configuration.