Unexpected data on ttyTCU0

Issue Overview

Users are experiencing unexpected behavior when sending data through the UART channel "ttyTCU0" on the Nvidia Jetson Orin Nano Dev board. The specific issue involves the transmission of hex data, where an extra byte "FF" is appended to the data being sent. For instance, when sending the sequence “00 11 22 33 FF”, the external device receives “00 11 22 33 FF FF”. This duplication occurs particularly when the data stream includes the byte “0xFF”, leading to further complications in communication.

The problem arises during data transmission using the third-party tool "cutecom". Users have confirmed that this issue consistently manifests when utilizing ttyTCU0 for communication, which is primarily intended for serial console logs. The impact of this issue can severely disrupt data integrity and communication with external devices, leading to errors and misinterpretations of transmitted information.

Possible Causes

• Hardware Incompatibility: The use of ttyTCU0, which is designed for console logging, may not support standard UART communication effectively, leading to unexpected byte duplication.

• Software Bugs or Conflicts: There may be bugs in the Jetpack version or conflicts with the third-party tool "cutecom" that affect how data is processed and transmitted through ttyTCU0.

• Configuration Errors: Incorrect settings or configurations in the UART setup may result in improper handling of transmitted data.

• Driver Issues: The drivers associated with ttyTCU0 might not handle certain byte sequences correctly, especially those involving “0xFF”.

• User Errors or Misconfigurations: Users might be unintentionally using ttyTCU0 for purposes it was not designed for, such as direct communication with external devices.

Troubleshooting Steps, Solutions & Fixes

1. Verify Jetpack Version:

   • Check the version of Jetpack being used as it may contain relevant fixes or updates. Use the command:

     dpkg -l | grep jetpack
     

2. Switch UART Interfaces:

   • Instead of using ttyTCU0, try using UART1 (/dev/ttyTHS0) for communication with external devices. This interface is more suitable for general UART tasks and may resolve issues related to data duplication.

3. Test Data Transmission:

   • Use a different terminal program (e.g., minicom or screen) to send data and observe if the duplication still occurs. This can help isolate whether the issue is with "cutecom".

4. Check Hardware Configuration:

   • Ensure that the custom carrier board is properly configured and that all connections are secure. Misconnections can lead to erratic behavior.

5. Inspect Driver Installation:

   • Ensure that all necessary drivers are installed and up-to-date. Reinstalling or updating drivers related to UART communication might help resolve underlying issues.

6. Monitor Console Logs:

   • Use dmesg or check /var/log/syslog to see if there are any error messages related to UART communication that could provide insight into what might be going wrong.

7. Testing with Different Data Patterns:

   • Experiment by sending different byte sequences (avoiding “0xFF”) to see if similar duplication occurs with other patterns, which could help identify if this is an isolated case.

8. Consult Documentation:

   • Refer to Nvidia’s documentation on UART interfaces for Orin Nano/NX for additional insights and best practices regarding UART configurations.

9. Best Practices for Future Communication:

   • Always use designated UART interfaces for specific tasks (e.g., avoid using ttyTCU0 for device communication).
   • Regularly update software and firmware to benefit from patches and improvements.

10. Further Investigation Needed:

    • If issues persist after trying these steps, consider reaching out to Nvidia support or community forums for additional assistance as there may be unresolved bugs or hardware-specific issues at play.

By following these steps, users should be able to diagnose and potentially fix the issue related to unexpected data transmission on ttyTCU0 while maximizing their Jetson Orin Nano Dev board’s functionality.