CSI Interface Speed Discrepancy on Jetson Orin Nano Module

Issue Overview

Users have identified a discrepancy between the stated and actual CSI (Camera Serial Interface) speeds supported by the Nvidia Jetson Orin Nano Module. The datasheet indicates support for MIPI D-PHY 2.1 with 8 lanes, suggesting a theoretical maximum speed of 36 Gbps. However, the actual supported speed is limited to 20 Gbps, causing confusion among developers and potential users.

Possible Causes

1. Outdated Documentation: The datasheet may not reflect the current design specifications of the Orin Nano Module.

2. Hardware Limitations: The actual hardware implementation may not fully utilize the theoretical capabilities of the D-PHY 2.1 standard.

3. Design Changes: Recent design modifications may have altered the CSI interface configuration, moving from an 8-lane to a 4-brick system.

4. Misinterpretation of Specifications: There could be a misunderstanding of how the lanes and speeds are calculated or presented in the documentation.

Troubleshooting Steps, Solutions & Fixes

1. Consult Updated Documentation:

   • Download the latest design guide from the Nvidia download center.
   • Review the most recent datasheet for the Jetson Orin Nano Module to ensure you have the latest specifications.

2. Understand Current Design Specifications:

   • The current design supports 4 lanes per brick with 4 bricks, not the 8-lane mode mentioned in older documentation.
   • Maximum DPHY speed is currently limited to 2.5 Gbps per lane.

3. Calculate Actual Bandwidth:

   • Use the formula: (2.5 Gbps/lane * 4 lanes/brick * 4 Bricks) = 40 Gbps theoretical maximum.
   • Note that the actual usable bandwidth may be lower due to overhead and other factors.

4. Check for Software Limitations:

   • Ensure that your software and drivers are up to date, as they may impact the achievable speeds.
   • Use the following command to check the current CSI configuration:

     sudo nvargus-daemon --query-sensors
     

5. Contact Nvidia Support:

   • If discrepancies persist between documentation and actual performance, reach out to Nvidia support for clarification.
   • Provide them with the specific version numbers of your datasheets and the model of your Jetson Orin Nano Module.

6. Community Forums:

   • Engage with the Nvidia developer community forums for peer support and the latest information on hardware capabilities.
   • Share your findings to help others who may encounter similar issues.

7. Hardware Verification:

   • If possible, use oscilloscope or logic analyzer to verify the actual signaling rates on the CSI lanes.
   • Compare the measured values with the stated specifications in the documentation.

8. Application Optimization:

   • Design your applications to work within the confirmed 20 Gbps bandwidth limitation.
   • Consider data compression or frame rate adjustments if higher throughput is required.

9. Stay Informed:

   • Regularly check for firmware updates that may address or improve CSI performance.
   • Subscribe to Nvidia’s developer newsletter for announcements on hardware updates or specification changes.