Issue regarding the Configuration of GRTC in nRf54L15-DK

RE: Issue regarding the Configuration of GRTC in nRf54L15-DK

Mohammed Hashir P — Thu, 31 Jul 2025 05:16:33 GMT

Thanks for your response.

RE: Issue regarding the Configuration of GRTC in nRf54L15-DK

Håkon Alseth — Tue, 29 Jul 2025 08:48:14 GMT

Hi,

The sample zephyr/samples/boards/nordic/system_off, when setting CONFIG_GRTC_WAKEUP_ENABLE=y, supports this.

Add a line like this:

printk("Uptime: %d\n", k_uptime_get_32());

And you will see that the uptime is not reset after each wake up period.

Kind regards,

Håkon

RE: Issue regarding the Configuration of GRTC in nRf54L15-DK

Mohammed Hashir P — Tue, 29 Jul 2025 06:59:41 GMT

Hi Håkon,

Thanks for your response.

However, my use case specifically requires the system to wake up from system-off (deep sleep) mode using the GRTC peripheral, not just timekeeping or delays in active mode.

As far as I understand, in system-off mode, the normal Zephyr k_timer or kernel tick-based mechanisms (like k_sleep) are not functional, and GRTC is the only available wake-up source via its compare channels.

Could you please clarify:

How to correctly configure the GRTC for wake-up from system-off on the nRF54L15-DK (SDK v3.0.2)?
Are there any required configurations in the DeviceTree, prj.conf, or special APIs (such as nrfx_grtc) to enable this?

Thanks,
Mohammed Hashir P

RE: Issue regarding the Configuration of GRTC in nRf54L15-DK

Håkon Alseth — Mon, 28 Jul 2025 12:53:46 GMT

Hi,

The GRTC is already in use by the kernel, so you can use the k_timer instance for time keeping (or k_sleep() for waits):

https://docs.zephyrproject.org/latest/kernel/services/timing/timers.html

Kind regards,

Håkon