TASKS_CONSTLAT is not working on NRF54L15

[gandyhuang]

HI,

I am using "NRF_POWER->TASKS_CONSTLAT = 1;" to enable CONSTLAT, but when i  printf("TASKS_CONSTLAT %d",NRF_POWER->CONSTLATSTAT); the result is still 0; how can i  config it? thanks

  

[Emil Lenngren]

Do you use BLE or MPSL? In that case I guess you need to use this function https://github.com/NordicSemiconductor/nrfx/blob/32f47b3f6cadb175266e3a9c5faf4a730ad76ac0/drivers/include/nrfx_power.h#L361 because MPSL will also switch to/from constant latency during radio events. Note that I haven't tested if it works myself nor checked which Kconfig settings must be applied.

[Ramakrishnan]

I found this reply helpful as I was facing an issue with cross-domain and  SPI access failing. Setting CONFIG_SOC_NRF_FORCE_CONSTLAT=y wasn't helpful and mpsl ( mpsl_init ) was bringing it out of that mode.

Issuing nrfx API call from application to set the constlat mode again before pulling down the CS helped resolving the issue.

[Vidar Berg]

For Cross power-domain use, please refer to the SDK documentation here: https://docs.nordicsemi.com/bundle/ncs-3.2.4/page/nrf/app_dev/device_guides/nrf54l/pinmap.html. Keep in mind that the sleep current increases while constant latency is enabled (typ. from 3 ua to 500ua).