[nRF9160] Override DTS File Used for S/NS Build

[phipi]

I have created an out of tree board folder following the same pattern as the Nordic PCA10090 and that is working as expected. What I would like to do now is have 2 versions of my dts. For the purpose of this let's say one would be a debug version where the UART logs are written to the USB port and one is a release version where UART is output to some other pins.

The current structure in the boards folder is:

board_name
└── board_name_common.dts
└── board_name_common_debug.dts
└── board_name_ns.dts
└── board_name.dts

And according to the Zephyr documentation:

The Zephyr build system begins creation of a devicetree by running the C preprocessor on a file which includes the following:

    The board’s devicetree source file, which by default is the Zephyr file boards/<ARCHITECTURE>/<BOARD>/<BOARD>.dts. (This location can be overridden by setting the DTS_SOURCE CMake variable.)

    Any file or files given by the DTC_OVERLAY_FILE CMake variable.

However, I'm not sure how/if the DTS_SOURCE flag is able to work with the NCS build system since I know there is some renaming of the board throughout the build process to facilitate the building of the two images.

Is this possible? If so, how do I do it?

[Didrik Rokhaug]

Hi.

You could make a separate .dts file and when building use a one time CMake argument: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.2.0/zephyr/guides/west/build-flash-debug.html#one-time-cmake-arguments

E.g. put the differences between the "normal" and "debug" board in an overlay file. Then, when you build your project for the "debug" board, you provide the overlay file as a CMake argument on the command line.

Best regards,

Didrik

[phipi]

Is it possible to have multiple overlays? I'm guessing in this case there would be an overlay in the boards directory but it may still be necessary to have one in the application as well.

[Didrik Rokhaug]

Do you mean a per-project overlay in addition to a debug overlay?

The point of the device tree is to describe the hardware (and other non-changing properties) of a board.

It might be easier to simply have two different boards, one for "debug" and one for "production". You can then take out the common part and put it in a common .dtsi file that is included in both the boards.

Another thing you can look at is whether you can do the configuration in Kconfig, which is much better suited for per-build configuration than the device tree.