Disabling RTC for low power mode

[StanislavDimitrov]

Dears, I want to disable the RTC for low power completly, and not populate the quartz used for it. The system will not go to sleep. Is this possible?

[Einar Thorsrud]

Hi,

The 32.768 kHz clock is optional, you can use the LFRC instead (if using the nRF Connect SDK, see this post for how to use it). With this, the RTC runs of the internal LFRC instead. Most applications use the RTC though, regardless of which SDK you use.

[StanislavDimitrov]

Thanks. What about NRF5 SDK17 ?

[Einar Thorsrud]

Virtually all nRF5 SDK examples use the RTC as it is used for time keeping while in low power mode. The SoftDvice also use the RTC and that is not confiugrable, so if you are using the SoftDevice (that would be in any BLE application), one RTC will always run.

Can you elaborate a bit more about why you don't what the RTC? I am wondering if ther eis perhaps a misunderstanding, as it is difficult to see many application sthat would benefit from it.

Note that there is one special case: In system off low powe rmode, you shut down everything, including the low frequency clcok and RTCs. But then the wake up sources are limtied to a few selected, most importantly GPIO, LPCOMP and pin reset, and wakeup is always in form of a reset.

[StanislavDimitrov]

We do not want to use low-power mode at all. The system only connects at power up, sends some data, and that's all. Nothing more.

[Einar Thorsrud]

I see. Then I don't see any problem? (But regardless, you will need to rune the RTC and a 32.768 kHz internal LFRC oscillator)

[StanislavDimitrov]

Thanks !