How to select UART pins for nRF9160

[CWallach]

How exactly are the UART pins selected for the nRF9160?  I've searched and am unable to find a file to configure pins.  I need to change to pins from the development board to the target hardware.

Thanks

[Didrik Rokhaug]

Hi.

Hardware specific configuration is (usually, there are some samples and modules that break this rule) done by the device tree of your device.

If you have created custom HW, I would recommend that you define your own board in NCS. Documentation on how to do that can be found here:

https://devzone.nordicsemi.com/nordic/cellular-iot-guides/b/getting-started-cellular/posts/nrf-connect-sdk-tutorial---part-2

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/application/index.html#custom-board-devicetree-and-soc-definitions

If you want to keep using the DK (either the physical HW or the board definition), you can change the pin assignment using an overlay file:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/application/index.html#device-tree-overlays

Note that if you are using SPM (which you are if your application is running in the non-secure domain), or MCUBoot and using pre-defined boards, you must add overlay files to SPM and MCUBoot as well. As these are running as secure, the overlay file must be for the secure variant of the board (not ns).

For more general documentation about device trees, see here: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/guides/dts/index.html

Best regards,

Didrik