Not able to access/find /dev/ttyTHS0 on Jetson Orin Nano Devkit – NVIDIA Official Board

Issue Overview

Users are experiencing difficulties accessing the UART interface on the Nvidia Jetson Orin Nano Dev board, specifically the inability to find the device node /dev/ttyTHS0. The issue arises when attempting to connect using 3-wire UART (TX, RX, and Ground) at the designated pin locations: Pin 9 (GND), Pin 8 (UART1_TX), and Pin 10 (UART1_RX).

Symptoms include:

• The command ls -l /dev | grep ttyTHS returns only /dev/ttyTHS1 and /dev/ttyTHS2, with no mention of /dev/ttyTHS0.
• Users have reported successful access to /dev/ttyTHS1 after changing the port designation.

The context of the problem typically occurs during setup or while trying to interface with external devices via UART. Users have indicated that they are using the official development kit, and some have noted that they are running Jetpack version JP6.0GA with a specific kernel version (5.15.136-tegra).

This issue seems to be relatively common among users, impacting their ability to establish serial communication, which is crucial for various applications.

Possible Causes

Several potential causes for this issue have been identified:

• Hardware Incompatibilities or Defects: The UART pins may not be correctly mapped or could be defective on certain boards.

• Software Bugs or Conflicts: There may be bugs in the Jetpack software or conflicts with other drivers that prevent proper recognition of the UART ports.

• Configuration Errors: Incorrect configurations in the device tree or system settings might lead to missing device nodes.

• Driver Issues: The kernel version in use might not support certain features or configurations expected by users.

• Environmental Factors: Power supply issues or overheating could affect hardware performance and functionality.

• User Errors or Misconfigurations: Users may mistakenly reference incorrect device nodes due to a lack of documentation or understanding of the mapping.

Troubleshooting Steps, Solutions & Fixes

To resolve the issue of accessing /dev/ttyTHS0, users can follow these troubleshooting steps and solutions:

1. Verify Hardware Connections:

   • Ensure that the UART wires are properly connected to the correct pins (Pin 8 for TX and Pin 10 for RX).
   • Check for any visible damage on the board or connectors.

2. Check Device Node Availability:

   • Run the command:

     ls -l /dev | grep ttyTHS
     

   • Confirm whether /dev/ttyTHS1 and /dev/ttyTHS2 are present, as these may be usable alternatives.

3. Consult Device Tree Information:

   • Access the device tree configuration to verify how UART ports are defined. This can typically be done by checking relevant files in /boot/dtb/ or using tools like dtc (Device Tree Compiler).

4. Modify Port Reference:

   • If /dev/ttyTHS0 is not found, try changing your code or application settings to use /dev/ttyTHS1, as this has been successful for other users.

5. Update Software and Drivers:

   • Ensure that you are running the latest version of Jetpack and related drivers. Check for updates that might address known issues.
   • Use commands such as:

     sudo apt update
     sudo apt upgrade
     

6. Review Documentation:

   • While there is limited documentation on device node mapping, refer to any available resources related to Jetpack versions and UART configurations. Community forums may also provide additional insights.

7. Test with Different Configurations:

   • If possible, test with another Jetson Orin Nano Dev board to determine if the issue is hardware-specific.
   • Experiment with different UART settings in your application code.

8. Best Practices for Future Prevention:

   • Document any changes made during setup for future reference.
   • Regularly check for firmware updates and community discussions regarding known issues.

If problems persist after following these steps, further investigation may be necessary, potentially involving NVIDIA support channels or community forums for additional assistance.