NCS/Zephyr - Dynamically modifying pin's function at runtime

[eyalasko]

Hi,

What would be the best way to alter pin's functionality from UART TX ->RX->GPOUT ->GPIN in runtime? (NCS2.5/Zephyr nRF52840)

• Is it supported by Zephyr/devicetree (this old thread says it's not, but maybe it has changed since)?
• If such functionality is not supported, how do I modify the dt overlay to exclude these multi-function pins but keep rest of the dt functions intact?
• What examples can I follow?

Thanks for any advice

[Maria Gilje]

Hello,

Zephyr offers Dynamic pin control now, but it is only meant to be used for uninitialized devices. The recommendation is to use only in early boot stages. From your description it seems the Dynamic pin control is not a good match, but I wanted to include it for completeness.

A possibility is to use nrfx drivers instead of Zephyr drivers. There is an nrfx driver and HAL for UART and HAL for GPIO. Note that when assigning pins with nrfx you can't use them with Zephyr. This option requires that you have full control over what you are doing, though.

Some examples using the nrfx drivers and HAL is the nrfx peripheral resource sharing example and nrfx use example.

Best regards,

Maria

[eyalasko]

Thanks for your prompt response.

If going for NRFX drivers as you advised, should I remove all references to this UARTE from the devicetree as well (or would it suffice just not to use it in the Zephyr way?)

What *.h files should be included  (I tried to #include <nrf_gpio.h> but got a build error)

btw,

be advised the NRFX UARTE doumentation mentions tx_cache/rx_cache which are not available in nrfx_uarte.h...

[Maria Gilje]

Sorry about the delay.

Your devicetree can stay as it was.

eyalasko said:

What *.h files should be included  (I tried to #include <nrf_gpio.h> but got a build error)

Did you look at the samples I linked in my previous answers? Here is a link to the 2.5.0 versions on github as well: nrfx prs and nrfx use

eyalasko said:

be advised the NRFX UARTE doumentation mentions tx_cache/rx_cache which are not available in nrfx_uarte.h...

tx_cache and rx_cache are in the main branch of NCS but not in any of the currently tagged releases (latest is v2.5.1).

Best regards,

Maria