About removing the 32.768kHz crystal oscillator

RE: About removing the 32.768kHz crystal oscillator

PaKa — Mon, 27 Oct 2025 14:09:39 GMT

Power On All Idle is the mode with the lowest power consumption when using the LFRC. This means the device is active but everything can be stopped.

RE: About removing the 32.768kHz crystal oscillator

Rekolhy — Mon, 27 Oct 2025 13:08:16 GMT

Thanks for the reminder. May I ask which sleep mode I can enter and use the RTC for wake-up when only using a 32MHz external crystal?

RE: About removing the 32.768kHz crystal oscillator

PaKa — Mon, 27 Oct 2025 12:59:10 GMT

Note: for GRTC in system off you need to have the 32KHz crystal mounted, this mode is not available with the LFRC

RE: About removing the 32.768kHz crystal oscillator

Ressa — Mon, 27 Oct 2025 12:29:38 GMT

Hi,
You can check the below sample as it can be used for evaluating different power modes:
Bluetooth: Peripheral power profiling

Best regards,
Ressa

RE: About removing the 32.768kHz crystal oscillator

Rekolhy — Mon, 27 Oct 2025 11:39:24 GMT

Hello,
Could you please provide relevant examples for entering system off mode and RTC wake-up from system off mode?
Thank you.

RE: About removing the 32.768kHz crystal oscillator

Ressa — Wed, 22 Oct 2025 10:38:09 GMT

Glad to hear it is working. Yes you can have only 32MHz external crystal and still enter and wake up from sleep mode, in that case internal LFRC will be used.

Best regards,
Ressa

RE: About removing the 32.768kHz crystal oscillator

Rekolhy — Wed, 22 Oct 2025 06:18:36 GMT

Thank you very much，
My issue has been resolved. I have an additional question: Can the system enter sleep mode and wake up periodically when using only a 32MHz crystal oscillator?
Thank you.

RE: About removing the 32.768kHz crystal oscillator

Ressa — Mon, 20 Oct 2025 09:29:10 GMT

Hi,

Thanks for contacting us. When using only 32 MHz crystal oscillator (and no 32.768 kHz crystal), special software configuration is required. By default, SDK expects a 32.768 kHz crystal (LFXO) for the LFCLK, which is used by system timers, the RTC, and functions like k_msleep.
You need to configure your firmware to use the internal RC oscillator (LFRC) as the LFCLK source instead of external crystal. For that purpose, please add the following line to your prj.conf file (project configuration file):

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y

This tells the system to use the internal RC oscillator.

Best regards,
Ressa