Devicetree overlay for simple GPIO

RE: Devicetree overlay for simple GPIO

Menon — Wed, 28 Dec 2022 10:05:33 GMT

Hello,

Glad to hear it worked.

Kind Regards,

Abhijith

RE: Devicetree overlay for simple GPIO

Lorozco — Tue, 27 Dec 2022 02:36:17 GMT

Just to close this out - your link above helped me figure out my issue (which was due to my unfamiliarity with devicetree syntax!)

To add new nodes, the correct syntax is

/{
SampleSignals
    {
     compatible = "gpio-keys";
      input_signal1: input_signal1
      {
         gpios = <&gpio0 2 GPIO_ACTIVE_HIGH>;
          label = "Name your GPIO Signal";
        };
    };
};

However, if you are overriding something like an i2c bus, then no 'root' syntax is required:

&i2c0
{
    new_i2c_device0: i2c_device@30
    {
        compatible = "i2c-device";
        reg = < 0x30 >;
        label = "First new I2C device";
    };
};

Adding the two snippets above to an .overlay file works and does not require modifying the original .dts file in the sdk directories.

Thanks again for the help!

RE: Devicetree overlay for simple GPIO

Menon — Thu, 22 Dec 2022 12:54:11 GMT

Hello,

Thank you for clarifying your issue.

But I think this has been discussed in various other tickets. For eg: Look at this ticket from my colleague there he shows how to add this in overlay file.

Let me know if this not what you are looking for. Please expect a delay after this response as I will be away for Christmas vacation and whole Devzone is working understaffed.

Kind Regards,

Abhijith

RE: Devicetree overlay for simple GPIO

Lorozco — Wed, 21 Dec 2022 22:41:02 GMT

Also, just to be clear, if I add

sample_gpio_signals

{

compatible = "gpio-keys";

columnswitchint: column_switch_input

{

gpios = <&gpio0 2 GPIO_ACTIVE_LOW>;

label = "Column Switch Interrupt Signal";

};

To the .dts file (and not the overlay file), the project builds and works just fine. My concern with this is that now I've modified a file that is not in my project directory and I can't easily commit it to my repository.

RE: Devicetree overlay for simple GPIO

Lorozco — Wed, 21 Dec 2022 22:00:28 GMT

Actually, if you can just point me to an example that toggles a GPIO pin on the nrf52840dk that is NOT one of the on-board LEDs, that will probably be enough to get me pointed in the right direction.

Ideally the example should use a .overlay file (and not modify the original .dts file).

RE: Devicetree overlay for simple GPIO

Lorozco — Wed, 21 Dec 2022 16:16:38 GMT

Hi Abhijith,

I understand what you're saying, but the "gpio-keys" binding I am trying to use is already present at

ncs\v2.1.2\zephyr\dts\bindings\gpio

The file nrf52840dk_nrf52840.dts generated by the blinky example uses the 'gpio-keys' binding with no issues, so why can't I use it as well on my .overlay file?

Also, if I am going to create my own binding files (which I've tried and not been successful yet), I would like to create them in my own application directory (and not in the ncs\xx\xx structure) so that I can commit them to my repository with the rest of my project files, but this is a separate topic. For now, I just want to be able to use the 'gpio-keys' binding in my overlay file (or any other binding in the ncs\v2.1.2\zephyr\dts\bindings for that matter).

Thanks

RE: Devicetree overlay for simple GPIO

Menon — Wed, 21 Dec 2022 15:40:31 GMT

Hello,

I think the issue is with the compatible section here. AFAIK, the system always looks for the matching binding file and for this compatible properties are used. Take a look at this page which explains more on this. I think you need to create a binding file inside ncs\v2.x.x\nrf\dts\bindings and then add this to your dts node.
Creating binding file is explained here. Something like below need to be created. Each section inside the yaml file is described here.

description: GPIO test

compatible: "xyz,test"

include: base.yaml

properties:
  status:
    required: true

  gpios:
    type: phandle-array
    required: true
    description: |
      GPIO to use as testpin.

Try adding this to your dts node. Something like below

xyz: test {
	compatible = "xyz,test";
	gpios = <&gpio0 29 GPIO_ACTIVE_HIGH>;
};

I am not completely sure on this as I haven't tried this before. Give it a shot and let me know.

Kind Regards,

Abhijith

RE: Devicetree overlay for simple GPIO

Lorozco — Wed, 21 Dec 2022 00:09:54 GMT

..and I apologize in advance for the terrible formatting!