RFComm TTY Support Not Available on Nvidia Jetson Orin Nano

Issue Overview

Users of the Nvidia Jetson Orin Nano Developer Kit are encountering an issue when attempting to establish Bluetooth serial communication using RFCOMM. The specific error message received is "RFCOMM TTY support not available" when executing the command:

sudo rfcomm bind 0 00:1A:7D:DA:71:13

This problem arises during the setup phase, specifically when users try to connect their Jetson device to a PC via Bluetooth for serial data transfer. The hardware specifications for the affected device include:

• Module: NVIDIA Jetson Orin Nano (Developer Kit)
• Release: 5.10.120-tegra
• L4T: 35.4.1
• Jetpack: 5.1.2

The issue appears to be consistent across multiple attempts, significantly impacting the ability to utilize Bluetooth for communication, which may hinder projects reliant on wireless data transfer.

Possible Causes

Several potential causes have been identified for this issue:

• Kernel Configuration: The absence of the CONFIG_BT_RFCOMM_TTY module in the kernel configuration may prevent RFCOMM TTY support.

• Driver Issues: Missing or improperly configured Bluetooth drivers can lead to communication failures.

• Software Bugs or Conflicts: Incompatibilities between software versions or bugs in the current L4T or Jetpack releases may contribute to this problem.

• User Configuration Errors: Incorrect settings or commands during setup could also result in this error.

• Environmental Factors: Issues such as power supply instability or temperature extremes might affect Bluetooth performance.

Each of these causes can lead to the observed problem by either preventing necessary modules from loading or misconfiguring the Bluetooth stack on the device.

Troubleshooting Steps, Solutions & Fixes

To resolve the "RFCOMM TTY support not available" issue, follow these troubleshooting steps and potential solutions:

1. Check Kernel Configuration:

   • Run the following command to check if RFCOMM TTY support is enabled:

     zcat /proc/config.gz | grep -i rfcomm
     

   • Look for CONFIG_BT_RFCOMM and CONFIG_BT_RFCOMM_TTY. If CONFIG_BT_RFCOMM_TTY is not set, it needs to be enabled.

2. Build CONFIG_BT_RFCOMM_TTY as a Module:

   • Download the kernel source for your specific L4T release (R35.4.1).
   • Configure the kernel:
     • Use a configuration editor like nconfig to enable CONFIG_BT_RFCOMM_TTY as a module:

       make tegra_defconfig
       make nconfig
       

     • Search for bt_rfcomm_tty and set it to =m.

3. Compile and Install Module:

   • Compile the kernel or module:

     make modules
     

   • Copy the compiled module to the appropriate directory and update module dependencies:

     sudo depmod -a
     

4. Cross-Compiling (if applicable):

   • If using an Ubuntu host PC for cross-compilation, follow official documentation for cross-compiling from L4T release pages, skipping installation instructions that mention flashing.

5. Testing Configuration:

   • After recompiling and installing, reboot your Jetson device.
   • Retry connecting using the rfcomm bind command.

6. Documentation and Resources:

   • Refer to Nvidia’s official documentation for detailed build steps and kernel configuration guidelines.
   • Ensure all relevant packages for Bluetooth communication are installed on your Jetson device.

7. Best Practices:

   • Regularly check for updates to L4T and Jetpack that may resolve underlying issues.
   • Maintain backups of working configurations before making changes.

Unresolved Aspects

While several users have reported success with enabling CONFIG_BT_RFCOMM_TTY as a module, further investigation may be needed regarding specific driver updates or compatibility issues with newer versions of L4T or Jetpack that could affect Bluetooth functionality on the Jetson Orin Nano.