nRF52's RTC in sleep mode

[msu7xi]

Hello,

My question is about the nRF52 DK's (nRF52832) RTC (Real Time Counter). Is there an sleep mode where the RTC continues counting while sleeping? In the application I'm developing I need to keep the time running while the microcontroller is in sleeping mode.

[khelmutlord]

Hello,

Are you using the nRF5 SDK or nRF Connect SDK? In either case, the RTC peripheral can be connected to the low frequency clock.

https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.nrf52832.ps.v1.1%2Frtc.html

The RTC can be configured to use the low frequency clock and can be used to generate an interrupt with most other system peripherals off. This would mean the microcontroller is in "system on sleep."

Hope this helps,

Helmut Lord

[msu7xi]

Hello,

Thanks for your reply. I'm using nRF Connect SDK in VS Code. If the microcontroller is in "system on sleep" can I wake it up with an external interruption? Or the only way to wake it up is with the RTC?

[khelmutlord]

Yes, in system on sleep the microcontroller can be interrupted by external sources using a GPIOTE interrupt. System off can also support a GPIOTE interrupt but most other peripherals (including the RTC) are shut down.

[msu7xi]

Thanks. Moreover I'd like to know if I must put the microcontroller in "system on sleep" with RAM retention or without it and if there is an example in Nordic's Github repository?

[Karl Ylvisaker]

Hello,

Unknown said:

Moreover I'd like to know if I must put the microcontroller in "system on sleep" with RAM retention or without it and if there is an example in Nordic's Github repository?

You could take a look at this example to see how this can be done.

Best regards,
Karl