CAN Bus Signal Issues on Nvidia Jetson Orin Nano Dev Board

Issue Overview

Users have reported difficulties in receiving CAN bus signals when using the Nvidia Jetson Orin Nano Development Kit. The specific symptoms include:

• Successful loopback tests but no signal detected on external devices such as a PCAN dongle or an oscilloscope when attempting to send CAN messages.
• The issue arises after rebooting the system and connecting a Waveshare SH65HVD230 CAN transceiver to the Jetson Orin Nano.
• The operating system in use is Jetpack 5.1.2, and users have confirmed proper wiring between the transceiver and the Jetson board.

The problem appears to be consistent, as multiple users have experienced similar issues. The impact on user experience is significant, as it prevents effective communication over the CAN bus, which is critical for applications requiring real-time data exchange.

Possible Causes

Several potential causes for the issue have been identified:

• Hardware Incompatibilities: There may be compatibility issues between the Jetson Orin Nano and the Waveshare CAN transceiver.

• Software Bugs or Conflicts: The installed version of Jetpack (5.1.2) may contain bugs affecting CAN bus functionality.

• Configuration Errors: Incorrect configuration of CAN settings or failure to properly initialize the CAN interface could lead to communication failures.

• Driver Issues: Missing or improperly loaded drivers for CAN communication might prevent successful signal transmission.

• Environmental Factors: Inadequate power supply or incorrect termination of the CAN bus could affect signal integrity.

• User Errors or Misconfigurations: Mistakes in wiring or configuration settings, such as bitrate mismatches or missing ground connections, can lead to issues.

Troubleshooting Steps, Solutions & Fixes

To diagnose and resolve the issue, follow these comprehensive troubleshooting steps:

1. Verify Hardware Connections:

   • Ensure proper wiring between the Jetson Orin Nano and the Waveshare transceiver:
     • 3.3V to 3.3V
     • GND to GND
     • CAN RX to CAN RX
     • CAN TX to CAN TX
   • Connect CANH and CANL to a DB9 connector that interfaces with the PCAN dongle.
   • Check for proper 120-ohm termination resistors at both ends of the CAN bus.

2. Check Ground Connections:

   • Ensure that all devices on the bus share a common ground connection. This is crucial for differential signaling integrity.

3. Run Diagnostic Commands:

   • Execute the following command to check the status of can0:

     sudo ip -d -s link show can0
     

   • Look for errors in transmission or reception that may indicate configuration issues.

4. Setup CAN Communication:

   • Use these commands to configure the CAN interface:

     sudo busybox devmem 0x0c303018 w 0xc458
     sudo busybox devmem 0x0c303010 w 0x400
     sudo busybox devmem 0x0c303010 w 0xc400
     sudo modprobe can
     sudo modprobe can_raw
     sudo modprobe mttcan
     sudo ip link set can0 up type can bitrate 1000000 sjw 4
     

5. Test Signal Transmission:

   • Send a test message using:

     cansend can0 123#abcdabcd
     

   • Monitor for signals on both PCAN Explorer and an oscilloscope.

6. Check Configuration Settings:

   • If issues persist, consider adjusting bitrate settings or adding parameters like sjw (Synchronization Jump Width) to optimize communication:

     sudo ip link set can0 up type can bitrate 1000000 sjw 4
     

7. Consult Documentation & Updates:

   • Ensure that you are using the latest drivers and firmware for both the Jetson Orin Nano and the Waveshare transceiver.
   • Review relevant documentation for any specific setup instructions related to your hardware.

8. Isolate Hardware Issues:

   • If possible, test with another Jetson Orin Nano or a different CAN transceiver to rule out hardware defects.

9. Best Practices:

   • Maintain proper cabling practices by using twisted pair cables for CANH and CANL.
   • Ensure that devices are spaced adequately (at least 0.5m apart) to avoid interference.

Unresolved aspects of this issue may include specific software bugs in Jetpack 5.1.2 that require further investigation by Nvidia support or community forums for updates or patches.