Can’t use CAM0_PWDN on Jetson Orin Nano DevKit over script

Issue Overview

Users are experiencing difficulties utilizing the CAM0_PWDN pin on the Nvidia Jetson Orin Nano Developer Kit while attempting to control a MIPI CSI camera. The main symptoms include:

• Invalid Channel Errors: When users try to set up the CAM0_PWDN pin (pin 114 on the J20 connector) using a Python script with the Jetson GPIO library, they receive an error stating that the channel is not valid.

• Inconsistent Pin Numbering: There is confusion regarding the correct GPIO number associated with CAM0_PWDN, with users reporting different values, such as 394 and 397, leading to further issues in script execution.

• Platform Specifications: The issue occurs on a platform running Jetpack 5.1.2 with Jetson Linux 35.4.1. The camera in use is a MIPI CSI IMX568c from Vision Components.

• Impact on Functionality: The inability to control the camera via the CAM0_PWDN pin affects users’ ability to capture images at specific moments, which is crucial for applications requiring precise triggering.

Possible Causes

• Incorrect Pin Numbering: Users may be referencing incorrect GPIO numbers for CAM0_PWDN, leading to invalid channel errors.

• Driver Conflicts: The GPIO pin may be reserved by a driver associated with the camera sensor, preventing user access.

• Software Bugs: There may be bugs in the Jetson GPIO library or conflicts between different versions of libraries or drivers.

• Configuration Errors: Misconfigurations in the device tree or GPIO setup may prevent proper access to the desired pin.

• User Errors: Incorrect usage of GPIO modes (BOARD vs BCM) or misinterpretation of documentation could lead to errors in setup.

Troubleshooting Steps, Solutions & Fixes

1. Verify Pin Numbering:

   • Check the correct GPIO number for CAM0_PWDN using:

     sudo cat /sys/kernel/debug/gpio
     

   • Confirm that it corresponds to PH.06 (which is reported as gpio-397).

2. Use Correct GPIO Mode:

   • Ensure you are using the correct numbering scheme (BCM or BOARD). For example, if using BCM:

     import Jetson.GPIO as GPIO
     GPIO.setmode(GPIO.BCM)
     

3. Test GPIO Access:

   • Attempt to control the pin using gpioset:

     gpioset gpiochip0 49=1  # To enable
     gpioset gpiochip0 49=0  # To disable
     

   • If errors persist, ensure that no other processes are using the GPIO pin.

4. Check Driver Usage:

   • If the output indicates that PH.06 is "used," you may need to unload any drivers associated with it:

     sudo rmmod <driver_name>
     

   • Replace <driver_name> with the actual driver name used for your camera module.

5. Modify Device Tree:

   • If you need to control the pin via gpiofs, consider modifying the device tree by removing references to PH.06 from it.
   • This can typically be done by editing .dtsi files and recompiling them, but ensure you understand how this affects your camera functionality.

6. Consult Documentation:

   • Review Nvidia’s documentation and community forums for updates or patches related to Jetpack and GPIO usage.
   • Check for any firmware updates that may resolve existing bugs.

7. Testing with Alternative Libraries:

   • Consider trying other libraries or methods for controlling GPIO pins if issues persist with Jetson.GPIO.

8. Future Prevention:

   • Keep your software and drivers updated to avoid conflicts.
   • Regularly consult community forums for new insights or solutions related to common issues.

9. Unresolved Aspects:

   • Further investigation may be needed regarding how to balance using both software control via GPIO and maintaining camera functionality.
   • Users should explore whether there are alternative methods for triggering without losing access to camera features.

By following these steps, users should be able to diagnose and potentially resolve issues related to controlling the CAM0_PWDN pin on their Jetson Orin Nano Developer Kit effectively.