nrf54l15 bluetooth stretching spi clock

RE: nrf54l15 bluetooth stretching spi clock

Vidar Berg — Wed, 25 Feb 2026 17:53:03 GMT

Hi,

Good to hear, thanks for confirming that this was the issue.The nrf_sys_event_request_global_constlat() API is reference counted, so when it's called from the application, it prevents other modules such as the Bluetooth controller, from switching back to low-power mode until the application releases its request by calling nrf_sys_event_release_global_constlat(). The Bluetooth controller is using the constant latency sub power mode during BLE events to reduce interrupt latency.

RE: nrf54l15 bluetooth stretching spi clock

DannyDS — Wed, 25 Feb 2026 16:53:58 GMT

Hi,

Thank you for the quick reply,

Wrapping my SPI commands in nrf_sys_event_request_global_constlat() seems to have solved the problem,

I had already come across the power modes and thought that setting nrf_power_task_trigger(NRF_POWER, NRF_POWER_TASK_CONSTLAT);

would have been sufficient.

Many thanks,

Danny

RE: nrf54l15 bluetooth stretching spi clock

Vidar Berg — Wed, 25 Feb 2026 16:37:26 GMT

Hi,

I don't immediately see how you are applying the pin assignments, it doesn't seem to be through pinctrl, but your zephyr user node suggests your are using the dedicated pins on port 2 with the spim21 so I suspect you may be experiencing the same as discussed in this case: https://devzone.nordicsemi.com/f/nordic-q-a/126270/nrf54l15-spi-corruption-on-gpio2-p2-when-rtt-is-disconnected/557576

Best regards,

Vidar

RE: nrf54l15 bluetooth stretching spi clock

DannyDS — Wed, 25 Feb 2026 16:16:31 GMT

Hi,

here is a minimal reproducible project.

Just to note I have also discovered if you debug the application or connect to it via RTT viewer then the clock is fine.

Thanks,

Danny

devzone.nordicsemi.com/.../nrf54l15_5F00_spi_5F00_ble_5F00_demo.zip

RE: nrf54l15 bluetooth stretching spi clock

PaKa — Wed, 25 Feb 2026 12:03:33 GMT

Which SPI and which port are you using?

RE: nrf54l15 bluetooth stretching spi clock

Vidar Berg — Wed, 25 Feb 2026 07:00:46 GMT

Hello Danny,

I have not seen this before. Are you able to share a minimal version of your project so I can try to see if this issue is reproducible on a nRF54l15 DK?

Best regards,

Vidar