External Hardware Trigger for CSI Cameras on Nvidia Jetson: Timeout Issues and Solutions

Issue Overview

Users of the Nvidia Jetson Orin Nano Dev board are experiencing challenges when implementing an external hardware trigger for CSI cameras. The specific issue involves:

• A system with 4 CSI cameras triggered by a GPIO signal from a PLC
• Long periods (minutes) without image capture, followed by bursts of ~30 FPS for 5-10 seconds
• Concerns about potential timeout issues with the camera connection
• Uncertainty about the ability to continuously listen for image frames using OpenCV image capture

The impact of this issue affects the functionality of systems requiring synchronized, externally triggered image capture, particularly in applications with irregular or burst-mode imaging requirements.

Possible Causes

1. Default Timeout Settings: The Jetson’s default camera capture timeout is set to 2500ms, which is insufficient for the described use case with long periods of inactivity.

2. Nvargus-daemon Configuration: The default configuration of the nvargus-daemon service may not support the required extended waiting periods for frames.

3. Camera Connection Instability: Extended periods without frame capture may lead to connection instability or disconnection of the CSI cameras.

4. Software Limitations: Standard image capture methods may not be designed to handle extremely irregular frame arrival patterns.

Troubleshooting Steps, Solutions & Fixes

1. Modify Timeout Settings:

   • Enable infinite timeout for the camera capture:

     export enableCamInfiniteTimeout=1
     

   • Note that this may cause the application to crash if no frames are received for an extended period.

2. Reconfigure Nvargus-daemon:

   • Stop the default nvargus-daemon service:

     sudo pkill nvargus-daemon
     

   • Set the infinite timeout environment variable:

     export enableCamInfiniteTimeout=1
     

   • Restart the nvargus-daemon with the new settings:

     sudo nvargus-daemon &
     

3. Implement Proactive Reconnection:

   • If possible, implement a system to reconnect cameras before the image capture burst:
     • Monitor the PLC signal or use a separate notification mechanism to predict when image capture will begin
     • Initiate a camera reconnection sequence just before the expected capture period

4. Optimize OpenCV Image Capture:

   • Modify the OpenCV capture code to handle potential timeouts or connection drops gracefully
   • Implement a retry mechanism for frame capture

5. Consider Alternative Capture Methods:

   • Explore using the GPIO signal to trigger the start of frame reception in software, rather than relying solely on continuous listening

6. Monitor System Logs:

   • Regularly check system logs for any camera-related errors or warnings
   • Use this information to fine-tune the timeout and reconnection strategies

7. Test Different Timeout Values:

   • If infinite timeout causes stability issues, experiment with longer, finite timeout values that exceed the expected gap between image bursts

8. Implement Watchdog Timer:

   • Create a software watchdog to monitor camera connections and automatically reinitialize them if no frames are received within a specified period

9. Optimize Camera Pipeline:

   • Ensure that the camera pipeline is optimized for quick startup and frame capture to minimize delays when triggering occurs

10. Consider Hardware Solutions:

    • If software solutions prove insufficient, explore hardware-level solutions such as camera interface boards designed for long-duration standby and rapid wake-up

By implementing these solutions and troubleshooting steps, users should be able to overcome the timeout issues and successfully use external hardware triggers for CSI cameras on the Nvidia Jetson platform, even with long periods of inactivity between capture bursts.