GPIO Issues in Jetpack 6.0 with Linux 36.3

Issue Overview

Users are experiencing difficulties with the GPIO (General Purpose Input/Output) functionality on the Nvidia Jetson Orin AGX when using Jetpack 6.0 (specifically version 36.3). The main symptoms include the inability to dynamically set GPIO pins, which previously worked in Jetpack 5.0 using both the /sys/class/gpio interface and gpioset commands. In Jetpack 6.0, the /sys/class/gpio interface has been removed, and users report that gpioset commands do not produce any output on the specified GPIO pins, such as GPIO09 (pin 32).

The issue occurs during attempts to configure GPIO pins after flashing the latest Jetpack release. Users have confirmed that the same hardware operates correctly under Jetpack 5.0, indicating a regression in functionality with Jetpack 6.0. The impact of this problem is significant, as it hinders the ability to control hardware components connected to these GPIO pins, affecting various applications and projects reliant on GPIO functionality.

Possible Causes

1. Hardware Incompatibilities or Defects: Although unlikely, there could be issues with the hardware configuration or defects in specific units.
2. Software Bugs or Conflicts: The removal of the /sys/class/gpio interface in Jetpack 6.0 may have introduced bugs affecting GPIO functionality.
3. Configuration Errors: Users must manually modify pin configurations in a pinmux spreadsheet to enable GPIO functionality, which may not be clear or straightforward.
4. Driver Issues: Changes in driver support for GPIO in Jetpack 6.0 could lead to failures in setting pin states.
5. Environmental Factors: External factors such as power supply issues could affect GPIO performance, although this is less common.
6. User Errors or Misconfigurations: Incorrectly configured pinmux settings or failure to reflash after modifications can lead to non-functional GPIO pins.

Troubleshooting Steps, Solutions & Fixes

1. Verify Pin Configuration:

   • Check the pinmux spreadsheet for your specific Jetson module and ensure that the desired GPIO pins are configured correctly as outputs.
   • Ensure that the "Pin Direction" is set to "Bidirectional" for GPIO usage.

2. Modify Pinmux Settings:

   • Download the relevant pinmuxing spreadsheet from Nvidia’s developer website.
   • Open the spreadsheet (note: it requires Excel for full functionality) and modify the settings for your desired GPIO pins.
   • Generate new device tree source files (dtsi) based on your modifications.

3. Reflash Device:

   • After modifying the pinmux settings, reflash your Jetson device with the updated dtsi files using SDK Manager or command line tools.

4. Testing with Commands:

   • Use gpioinfo to verify that your pins are recognized and their states can be changed:

     gpioinfo | grep PBB.00
     

   • To test setting a GPIO pin high and low:

     sudo gpioset gpiochip1 8=1 # Set high
     sudo gpioset gpiochip1 8=0 # Set low
     

5. Check for Updates:

   • Regularly check Nvidia’s forums and documentation for any updates regarding Jetpack 6.x that may address known issues with GPIO functionality.

6. Use Alternative Libraries:

   • If issues persist with Jetson.GPIO, consider using libgpiod, which may provide better support for GPIO operations under Jetpack 6.x.

7. Documentation and Community Support:

   • Refer to Nvidia’s official documentation for detailed instructions on modifying pinmux settings and troubleshooting GPIO issues.
   • Engage with community forums for shared experiences and solutions from other users facing similar challenges.

8. Persistent Changes:

   • Remember that changes made directly through register modifications will not persist after a reboot; use the pinmux spreadsheet for permanent configurations.

9. Unresolved Aspects:

   • Users have reported confusion regarding whether certain behaviors constitute bugs or expected changes in functionality; further clarification from Nvidia may be necessary.
   • Consider feedback mechanisms to inform Nvidia of user experiences regarding GPIO handling in future releases.

By following these steps, users should be able to diagnose and potentially resolve issues related to GPIO functionality on their Nvidia Jetson Orin AGX devices running Jetpack 6.x versions.