Guidance on Enabling GPS PPS Input on Jetson Orin Nano Developer Kit

[yamuna.g]

Dear NVIDIA Support Team,

I am working on a project using the Jetson Orin Nano Developer Kit with JetPack 6.2.1. I need to interface a GPS module that provides a 1-PPS (Pulse Per Second) signal and use it for accurate timestamp synchronization in my application.

I have verified the following on my system:

• Jetson Orin Nano Developer Kit
• JetPack 6.2.1
• PPS kernel support is enabled:
  • CONFIG_PPS=y
  • CONFIG_PPS_CLIENT_GPIO=y
  • CONFIG_PPS_CLIENT_KTIMER=y
• /sys/class/pps/pps0 is present and corresponds to the kernel timer (ktimer) PPS source.

I would like to use one of the 40-pin header GPIOs (currently considering pin 7, although I am open to using another recommended GPIO) as the PPS input.

I have a few questions regarding the correct implementation:

1. Which GPIO pins on the Jetson Orin Nano Developer Kit are officially recommended for receiving an external PPS signal?
2. What is the mapping between the 40-pin header GPIOs and the corresponding Tegra GPIO identifiers required in the device tree (for example, the value used in the gpios = <&tegra_main_gpio ...> property)?
3. Could you provide an example Device Tree Overlay (DTO) for enabling the pps-gpio driver on the Jetson Orin Nano Developer Kit?
4. Is there an officially supported procedure for enabling GPIO PPS on JetPack 6.2.1 without rebuilding the entire kernel?
5. After enabling the overlay, what is the recommended method to verify that the GPIO PPS source has been successfully registered (for example, creation of /dev/pps1 and expected dmesg messages)?
6. Are there any pinmux or GPIO configuration changes required before the selected header pin can be used by the pps-gpio driver?
7. Is there any NVIDIA documentation or sample project demonstrating GPIO-based PPS input on the Jetson Orin Nano Developer Kit?

Thank you in advance. I look forward to your guidance.

[KevinFFF]

Hi yamuna.g,

@yamuna.g

1. Which GPIO pins on the Jetson Orin Nano Developer Kit are officially recommended for receiving an external PPS signal?

You can select the desired pin from 40-pins header for this use case(GPIO/Input).
Please just configure it as GPIO/Input in pinmux spreadsheet before use.

@yamuna.g

2. What is the mapping between the 40-pin header GPIOs and the corresponding Tegra GPIO identifiers required in the device tree (for example, the value used in the gpios = <&tegra_main_gpio ...> property)?

Let me take PIN7 of 40 pins as example.
It is PAC.06 from the following table.

So, you need to configure gpios = <&gpio TEGRA234_MAIN_GPIO(AC, 6) GPIO_ACTIVE_HIGH>; in device tree.

@yamuna.g

3. Could you provide an example Device Tree Overlay (DTO) for enabling the pps-gpio driver on the Jetson Orin Nano Developer Kit?
4. Is there an officially supported procedure for enabling GPIO PPS on JetPack 6.2.1 without rebuilding the entire kernel?
5. After enabling the overlay, what is the recommended method to verify that the GPIO PPS source has been successfully registered (for example, creation of /dev/pps1 and expected dmesg messages)?
6. Are there any pinmux or GPIO configuration changes required before the selected header pin can be used by the pps-gpio driver?
7. Is there any NVIDIA documentation or sample project demonstrating GPIO-based PPS input on the Jetson Orin Nano Developer Kit?

You may refer to the following threads for the example configuration.
Pps_gpio interrupt not asserted - #8 by KevinFFF
PPS input to GPIO on Jetpack 6.1 - #8 by erik93
Pps_gpio interrupt not asserted - #8 by KevinFFF