NRF51 SYSTEM ON - RTC + external interrupt

[Gavin]

Is it possible to program an NRF51 to wake-up from SYSTEM ON by either RTC or external interrupt?

I have some sensors programmed to wake-up by RTC but I would also like the option of interrupting the sleep with a button press if I cannot wait. In essence, I would like the sleep to be interrupted by either - whichever happens first.

I'm working without a soft device.

[endnode]

Hi Gavin,

Sure it has. Both RTCx HW peripheral as well as GPIOTE can wake you by interrupt if your code entered "sleep" by WFI/WFE ARM instructions. You can also be woken up from System OFF by GPIO signal (e.g. button press) but RTC cannot run so this is not available.

Cheers Jan

[Gavin]

Thanks Jan. If I wanted it to wake on either RTC or external interrupt, would I call WFI or WFE? At the moment I am calling WFE (see below) but it does not respond to the external interrupt.

					// Enter System ON sleep mode
				__WFE();  
				// Make sure any pending events are cleared
				__SEV();
				__WFE();