Jetson.GPIO lib – PWM not working on Orin Nano Dev Kit

Issue Overview

Users are encountering difficulties with the PWM functionality on the Jetson Orin Nano Dev Kit, specifically regarding PIN32 (GPIO07). The main symptoms include:

• Error Messages: Users receive an "Errno 16 Device or resource busy" error when attempting to modify the device tree for PWM usage on PIN32.

• Context of the Problem: The issue arises during attempts to enable PWM functionality through the Jetson.GPIO library after users have already enabled all PWMs in the device tree. Despite successful detection of other PWM pins, PIN32 does not appear to be properly configured as a PWM pin in the library.

• Hardware and Software Specifications: Users are working with the Jetson Orin Nano Dev Kit, utilizing the Jetson.GPIO library for GPIO manipulation. The specific hardware details include:

  • Processor: A78AE
  • Memory: 32GB or 64GB RAM variants

• Frequency of the Issue: The problem appears to be consistent among multiple users who have reported similar experiences in the forum.

• Impact on User Experience: The inability to utilize PWM on PIN32 limits functionality for projects relying on PWM control, which can significantly hinder development efforts.

Possible Causes

Several potential causes for this issue have been identified:

• Hardware Incompatibilities: The pin mapping in the Jetson.GPIO library may not accurately reflect the capabilities of the Orin Nano Dev Kit, leading to missing references for certain PWM pins.

• Software Bugs or Conflicts: There may be bugs in the Jetson.GPIO library that prevent it from recognizing PIN32 as a PWM-capable pin.

• Configuration Errors: Incorrect settings in the device tree or pinmux configuration may lead to improper functionality.

• Driver Issues: Outdated or incompatible drivers could affect GPIO and PWM functionality.

• User Misconfigurations: Users might not have correctly configured their environment or device tree settings, leading to these issues.

Troubleshooting Steps, Solutions & Fixes

To address the PWM issue on the Jetson Orin Nano Dev Kit, users can follow these comprehensive troubleshooting steps:

1. Verify Device Tree Configuration:

   • Ensure that all necessary PWMs are enabled in the device tree. Use commands like:

     sudo cat /sys/kernel/debug/gpio | grep PG.06
     

2. Check Pin Mapping:

   • Review the pin mapping in the Jetson.GPIO library source code to confirm that PIN32 is defined correctly. Modify if necessary:

     (41, 'PG.06', "tegra234-gpio", 32, 12, 'GPIO07', 'GP113_PWM7', '32a0000.pwm', 0)
     

3. Use Alternative Libraries/Methods:

   • If Jetson.GPIO is not functioning as expected, consider using sysfs directly for PWM control. Example commands include:

     echo 1 > /sys/class/pwm/pwmchip0/export
     echo 1000000 > /sys/class/pwm/pwm0/period
     echo 500000 > /sys/class/pwm/pwm0/duty_cycle
     echo 1 > /sys/class/pwm/pwm0/enabled
     

4. Modify Pinmux Settings:

   • Utilize tools like Jetson-IO to modify pinmux settings for enabling PWM usage on specific pins.

5. Consult Documentation and Community Resources:

   • Refer to NVIDIA’s official documentation and community discussions for updates regarding Jetson.GPIO compatibility with Orin Nano.

6. Report Issues and Contribute Code:

   • If users have identified specific code changes that resolve their issues, they should consider submitting a pull request to the Jetson.GPIO GitHub repository to facilitate broader compatibility.

7. Monitor GitHub for Updates:

   • Keep an eye on NVIDIA’s GitHub page for any updates or fixes related to this issue.

8. Best Practices for Future Prevention:

   • Regularly check for software updates and documentation changes from NVIDIA.
   • Engage with community forums for shared experiences and solutions.

By following these steps, users can troubleshoot and potentially resolve issues related to PWM functionality on their Jetson Orin Nano Dev Kit effectively.