System Off mode in between beacon advertisement

[mariamb]

Hi,

We are developing an application with a custom nrf5340 board in which beacons are sent periodically every 100ms. We have been analyzing power consumption with a Power Profiler Kit and we have been able to send the device, whenever necessary, to System Off mode, which obviously stops the advertising and therefore drastically reduces consumption. 

After reading this post (https://devzone.nordicsemi.com/f/nordic-q-a/15062/power-optimizing-nrf-beacon) we got a bit confused and wonder if it is even possible to go into System Off mode and get those 17mA every time the device is not advertising, by means of waking up with a timer or any other option, considering we want it to be automatic and don't rely on any GPIO, NFC sense... 

Thank you so much!

Cheers!

[Simonr]

Hi

The case you have linked to is rather old, so when it was written, the nRF53 was not even announced yet. The nRF53 has one big difference from the nRF52 and nRF51 series, and that is the fact that it has two cores. This means that, in the nRF5340, you can put the Network core that is running the radio and advertisements to sleep (System OFF) while the Application core is doing something else entirely, for example keeping a timer of when to wake the network core up.

Best regards,

Simon

[mariamb]

Hi again,

We were trying to put the Network core to sleep as you pointed out, but we are not able to find its System OFF register direction in the documentation, apparently it only specifies the APPLICATION base addresses:

We wonder what the implementation would be like in case there is a register for it... From this list, how exactly would we wake the network core up from System OFF mode with the application core?:

• The DETECT signal, generated by the GPIO peripheral

• The ANADETECT signal, generated by the LPCOMP peripheral

• The SENSE signal, generated by the NFCT peripheral to wake-on-field

• A valid USB voltage on the VBUS pin is detected

• A debug session is started

• Pin reset

Or maybe we should use FORCE OFF mode instead? Is there any example available of any of this approaches?

Thanks again for your support!!