Jetson Orin Nano: Issues with I2C Bus 7 Not Working

Issue Overview

Users are experiencing issues with the I2C bus 7 on the Jetson Orin Nano Developer Kit. Specifically, the user reports that the I2C pins (3 and 5) are not functioning as expected when connected to an Arduino Uno. The command i2cdetect -y -r 7 does not display any detected addresses, indicating that the bus is not operational. In contrast, when the Arduino is connected to I2C bus 1 (pins 27 and 28), it is successfully detected. This inconsistency raises concerns about the functionality of I2C bus 7.

Relevant Hardware and Software Specifications

• Device: Jetson Orin Nano Developer Kit (8GB)
• JetPack Version: 6.0 DP
• Connection: Arduino Uno connected to I2C pins 3 (SDA) and 5 (SCL) on the Orin Nano.

Symptoms

• The command i2cdetect -y -r 7 returns no addresses found.
• The same Arduino Uno works correctly when connected to I2C bus 1 (pins 27 and 28).
• Users report timeout errors related to I2C communication in kernel logs.

Possible Causes

1. Pin Configuration Issues: The pinmux settings for I2C bus 7 may not be configured correctly, preventing proper operation of the SDA and SCL lines.
2. Driver Issues: There may be bugs or conflicts in the drivers that affect I2C communication on specific buses.
3. Hardware Connections: Physical connections or wiring issues could prevent proper communication over I2C bus 7.
4. Device Tree Configuration: The device tree may not correctly reflect the intended use of I2C bus 7, leading to misconfiguration.

Troubleshooting Steps, Solutions & Fixes

Step-by-Step Instructions

1. Verify Pin Connections:

   • Ensure that the SDA and SCL lines from the Arduino are securely connected to pins 3 and 5 on the Jetson Orin Nano.

2. Check Pin Configuration:

   • Use dmesg to check for any relevant error messages related to I2C:

     dmesg | grep i2c
     

3. Inspect Device Tree Settings:

   • Review and modify the device tree source files if necessary to ensure that I2C bus 7 is configured correctly.

4. Test with Different Devices:

   • If possible, connect a different I2C device to pins 3 and 5 to see if it is recognized, which can help determine if the issue lies with the Arduino or the Jetson board.

5. Use i2cdetect Command:

   • Run the command again after ensuring connections are correct:

     sudo i2cdetect -y -r 7
     

6. Check GPIO Configuration:

   • Ensure that GPIO settings do not conflict with I2C usage by checking GPIO states:

     sudo busybox devmem <address> 
     

7. Consult Documentation and Community Resources:

   • Refer to NVIDIA’s official documentation for guidance on configuring I2C buses and troubleshooting common issues.

Recommended Fixes

• Users have found success by ensuring correct pin configurations in the device tree and verifying physical connections.
• Modifying pinmux settings through device tree files has also been highlighted as a necessary step for proper functionality.

Best Practices for Future Prevention

• Document all configurations and changes made during development for future reference.
• Regularly check NVIDIA forums and documentation for updates regarding known issues with specific JetPack versions.

Unresolved Aspects and Further Investigation

• Users continue to seek clarity on how to effectively manage pinmux settings without extensive kernel modifications.
• There may be additional debugging steps required that are not fully documented in existing resources.

By following these troubleshooting steps and solutions, users can effectively address issues related to using I2C bus 7 on their Jetson Orin Nano platform while ensuring compatibility with their hardware configurations.