Extending Jetson.GPIO to support gpio pins that are not on the 40 pin header

Robotics & Edge Computing Jetson Systems Jetson Orin NX
1

Hello,

I have an Orin Nano Devkit and I’m prototyping an AR0821 camera module.

I am trying to use the CAM0_MCLK signal as a gpio line(gpio-440/GPIO3_PP.00) to use as a trigger for the camera.
I assumed that I would have to update the pinmux, so I changed it from EXT_PERIPH1_CLK to GPIO3_PP.00. This created a change in the DTSI file to

 extperiph1_clk_pp0 {
                            nvidia,pins = "extperiph1_clk_pp0";

  •                           nvidia,function = "extperiph1";

  •                           nvidia,function = "rsvd1";
                          nvidia,pull = <TEGRA_PIN_PULL_NONE>;
                          nvidia,tristate = <TEGRA_PIN_DISABLE>;
                          nvidia,enable-input = <TEGRA_PIN_DISABLE>;

Now I want to use the Jetson.GPIO python library to manage this pin.
What are the values for the fields in the table, JETSON_ORIN_NX_PIN_DEFS, in the file gpio_pin_data.py for a GPIO pin that is NOT on the 40 pin header, or does Jetson.GPIO only support the 40 pin header?

If I can’t use Jetson.GPIO, what is the best way for me to manage this particular GPIO pin?

Thanks!

3

Hi Blair010,

What’s the Jetpack version in use?

How do you configure it in pinmux spreadsheet?
Except for configuring it as GPIO3_PP.00 in “Customer Usage”, do you also configure it as Input/Int PD for your use case?

Jetson.GPIO is designed for 40-pins header, but you also can customize it for your use case.
e.g. if you want to add the support for PP.00, please try to configure it as following.

JETSON_ORIN_NX_PIN_DEFS = [
+   (92, 'PP.00', "tegra234-gpio", 41, 28, 'CAM0_MCLK', 'GP52_CLK1', None, None),
    (144, 'PAC.06', "tegra234-gpio", 7, 4, 'GPIO09', 'GP167', None, None),
    (112, 'PR.04', "tegra234-gpio", 11, 17, 'UART1_RTS', 'GP72_UART1_RTS_N', None, None),
4

Thanks for the quick response. Here’s the answers to your questions:
Jetpack version is 5.1.4
CAM0_MCLK is tied to the CAM_TRIGGER line on the AR0821 Camera.
I think I want the gpio pin to be an output, not an input, as toggling this pin will provide the trigger. Am I missing something?

Thanks for the JETSON_ORIN_NX_PIN_DEFS line.
How did you determine the values for fields 4 (41), 5 (28), and 7 (GP52_CLK1)?

Thanks!

5

Okay, sorry that I’m not clear about camera. It should be okay if you’ve configured it as Output in pinmux spreadsheet.

41 and 28 are just 2 unused number in the list.
You can find GP52_CLK1 in column E of pinmux spreadsheet as following
image

6

Thanks! That solved the problem. I had to “unhide” the columns in the Tegra pinmux Excel spreadsheet to see everything.