Options for peforming SPI i/o from the nrf54lm20 FLPR core

[pertan]

Hello,

I have a tight loop with strict timing requirements that I'd like to run on the FLPR core of the nrf54lm20. In each iteration of the loop, i need to write data to an IC over SPI. As far as I can tell, it's not possible to access the SPI peripheral from the FLPR. If this is indeed the case, I'm wondering what my options are. Can I somehow use the app core to set up autonomous SPI transfers and trigger these from the FLPR core somehow?

Any help would be much appreciated.

[Vidar Berg]

Hello,

The FLPR can actually access the peripherals, and it is possible to use the nrfx SPIM driver directly in the FLPR core firmware. However, please note that this is not officially listed as supported, so it should be considered experimental (https://nrfconnectdocs.nordicsemi.com/ncs/latest/nrf/app_dev/device_guides/nrf54l/vpr_flpr.html). The main thing to remember if you want to experiment with this is to assign the pins you want to use with SPI (e.g., SPI00 with GPIO P2) from the app core to the FLPR core through the devicetree similar to how it is done in the overlay here :https://github.com/nrfconnect/sdk-nrf/blob/633720f029ff76ccafcc780371138795d983690f/tests/zephyr/drivers/disk/disk_performance/boards/nrf54l15dk_nrf54l15_cpuapp.overlay#L46 

Best regards,

Vidar

[pertan]

Hi Vidar, thank you for the answer. Does "experimental" mean that it will be properly supported at some point in the future?

[Vidar Berg]

Hi, yes, plan is to support it. Unfortunately, I am not able to provide any timelines. If this is something that is important for your project, I recommend you reach out to our sales team at https://www.nordicsemi.com/About-us/Contact-Us