Unable to Use Only MOSI Line in SPI Configuration (Zephyr, WS2812)

RE: Unable to Use Only MOSI Line in SPI Configuration (Zephyr, WS2812)

SwRa — Fri, 06 Feb 2026 12:51:19 GMT

Hi Brent,

You are right. For nRF54L15, there’s no such requirement to have SCK connect to a pin input buffer for SPI to work.

Regards,

Swathy

RE: Unable to Use Only MOSI Line in SPI Configuration (Zephyr, WS2812)

Toastus — Wed, 04 Feb 2026 12:42:14 GMT

Is there any update on this?

Update: I have verified that I can build on nrf54L15 under 3.2.1 without assertions after defining a spi with only the MOSI pin defined, so this check has apparently been corrected. Note however in my case that I am not disconnecting pins in the source code, but instead used a device tree overlay in my application to simply remove the other pins from the pinctrl routines, removing the unused NRF_PSEL mappings.

RE: Unable to Use Only MOSI Line in SPI Configuration (Zephyr, WS2812)

SwRa — Thu, 03 Apr 2025 13:28:09 GMT

Hi Oleksander,

There was this limitation that the SCK pin needs to be connected in the nrf52 series where it states: "The SCK must always be connected to a pin, and that pin's input buffer must always be connected for the SPI to work." See here: https://docs.nordicsemi.com/bundle/ps_nrf52832/page/spi.html#d945e156

We will need to check if this is still a limitation on the nRF54L15 SPIM since the zephyr driver still enforces this limitation as of this day. If it is not, then the Zephyr driver can be updated to remove this limitation.. I will heck internally and get back to you with the updates.

Best Regards,

Swathy