Multiple nexus nodes, and using I2C on a nexus node

RE: Multiple nexus nodes, and using I2C on a nexus node

ljking2 — Sat, 14 Mar 2026 15:24:04 GMT

Followup: by following the example at https://github.com/zephyrproject-rtos/zephyr/tree/main/boards/shields/st_b_lcd40_dsi1_mb1166 I was able to get variants working.

I can now select which host connector the shield is connected to by accessing a variant. example: myshield_con1 or myshield_con2.

since I now have variants, each one calling a different overlay, I can define in the overlay which connector is in use, then call a common .dtsi that is the same for all of the variants.

similarly the nexus file can define several i2c different pinctrl sections and the shield overlay doesn't need know where the i2c is connected on the processor, the shield just needs to know which pinctrl to access. All of the cpu board connectivity information is hidden in the nexus file, the shields don't need to know about the board wiring.

example shield overlay:

#define CONNECTOR mycpu_con2
#define I2C_DEFAULT i2c_con2_default
#define I2C_SLEEP i2c_con2_sleep
#include "myshield.dtsi"

I then use CONNECTOR, I2C_DEFAULT, and I2C_SLEEP in myshield.dtsi.

RE: Multiple nexus nodes, and using I2C on a nexus node

ljking2 — Sat, 14 Mar 2026 14:52:20 GMT

I have figured out that the correct way to do this is with shield variants, Unfortunately....

I am having difficulty getting shield variants to work. I read the documentation here docs.zephyrproject.org/.../shields.html . I have locally setup the directory `zephyr/boards/shields/myshield/` with two files `myshield_v1.overlay` and `myshield_v2.overlay`, but I always get a compile error "Invalid SHIELD" when I add "--shield myshield_v2" to the west build command. myshield is in the list of shields to choose from, but the two variants are not. Is there something else I need to add (maybe a CMakeLists.txt?) to make shield variants work? I couldn't find an example to copy.

RE: Multiple nexus nodes, and using I2C on a nexus node

Kazi Afroza Sultana — Sun, 08 Mar 2026 09:36:26 GMT

Hello,

There is no documentation about passing a variable into a shield overlay to which nexus node it references.

Shield variants ([Shield variants]) documentation shows that some shields may support several variants or revisions. In that case, it is possible to provide multiple versions of the shields description each with its own overlay/defconfig, selected by --shield <shield_v2> etc.

Board compability (Board compatibility) shows how to configure shield per board (boards/shields/<shield>/boards/<board>*.overlay).

So, there both are static. There will be separate overlay for each case.

Regarding NRF_PSEL for nexus node, nexus nodes is only used for GPIO specifiers. There is no information indicating that NRF_PSEL can use nexus nodes or that pinctrl psels can be resolved via a nexus mapping. You can read this documentation Sound & edge blog; GPIO nexus nodes.

However, I will ask relevant team to get more insight. I will come back to you lately.

Thanks.

BR
Kazi