UART1 still conflict with SPI1 even if the status of UART1 is "disabled" in the zephyr.dts

[peter_liu]

I'm working on ncs 1.6.1 and nrf9160-DK.

I need to use SPI1, so i confirmed that UART1 is already disabled by default in  ncs\v1.6.1\zephyr\boards\arm\nrf9160dk_nrf9160\nrf9160dk_nrf9160ns.dts

and i also add a &uart1 status = "disabled" in my overlay files. however, the SPI1 didn't work , 

finally, the SPI1 works successfully only if i disable uart1 in ncs\v1.6.1\zephyr\boards\arm\nrf9160dk_nrf9160\nrf9160dk_nrf9160_common.dts

but i don't want to modify files in SDK like this, so, is there any way to  solve this in project files like overlay file?

[Vidar Berg]

Hello,

Please try to add the DTS overlay for the SPM subimage as well by adding a overlay named "nrf9160dk_nrf9160.overlay" in <project directory>\child_image\spm\nrf9160dk_nrf9160.overlay".

&uart1 {
	    status = "disabled";
};

Then to confirm that UART1 is indeed disabled by opening the <build directory>\spm\zephyr\zephyr.dts file and confirm that UART1 status is set to disabled:

Best regards,

Vidar

[peter_liu]

Hi,

I tried to add the <project directory>\child_imagespm\nrf9160dk_nrf9160.overlay, but the uart1's status is still "okay" in the <build directory>\spm\zephyr\zephyr.dts.

however, i found that the application sample "serial lte modem" doesn't have this problem (even its uart1's status is "okay" in the \spm\zephyr\zephyr.dts). so, after analyzing the differences, i find that adding "<project directory>\child_image\spm.conf" and only "CONFIG_SERIAL=n" in the spm.conf file can solve this problem.

do you know why?

[Vidar Berg]

Hi,

Yes, that will also work because it will prevent the SPM from initializing UART1. However, I'm not sure why status didn't change to "disabled". It worked when I tried it here.

[peter_liu]

So, the root cause of this problem is that the SPM occupies the uart1. correct?

and after all, I can change the spm\zephyr\zephyr.dts only if i add following script in my CmakeList.txt. 

set(spm_DTC_OVERLAY_FILE "${CMAKE_CURRENT_SOURCE_DIR}/${BOARD}.overlay")

while the spm.conf doesn't need any scripts to add, i wonder where is the file to define the locations of these .conf .overlay files? 

[Vidar Berg]

Yes, that's the root cause.

There are several ways you can apply overlays for a child images as described here: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/ug_multi_image.html#child-image-devicetree-overlays. I find it easiest to just add the overlay in the child_image folder like I suggested earlier.

<project directory>\child_image\spm\nrf9160dk_nrf9160.overlay"

peter_liu said:

I tried to add the <project directory>\child_imagespm\nrf9160dk_nrf9160.overlay, but the uart1's status is still "okay" in the <build directory>\spm\zephyr\zephyr.dts.

Is it a typo in your path here? It should be \child_image\spm\

[peter_liu]

Oh, It's just a typo here, i actually use the right path with my test.

[Vidar Berg]

OK, thanks for confirming. Either way, it's perfectly fine to point to the board overlay from your Cmakelist file.