Inadequate GPIO Current Output from Nvidia Jetson Orin Nano Dev Kit

Issue Overview

Users of the Nvidia Jetson Orin Nano Developer Kit are experiencing issues when attempting to drive DC motors using the "HandsOn Tech 7A/160W H-Bridge High Power DC Motor Driver Module." The main symptoms reported include:

• Low Current Output: The GPIO pins (specifically pin 33 and 15) are only providing approximately 0.5mA, which is insufficient for switching the logical levels required by the motor driver.
• Context of the Issue: This problem arises during the setup phase when users attempt to connect the Jetson’s GPIO pins to the motor driver after enabling PWM signals through a Python script.
• Hardware Specifications: The GPIO pins on the Orin Nano operate at 1.8V signals, while the carrier board utilizes TI TXB0108 level shifters to provide 3.3V signals.
• Frequency of Occurrence: This issue appears consistently among users attempting similar setups.
• Impact on User Experience: The inability to drive motors effectively limits the functionality of projects that rely on motor control, causing frustration and additional work for users.
• Additional Context: Users have noted that similar setups work with other boards like Raspberry Pi and ESP32, suggesting a specific limitation with the Jetson Orin Nano’s GPIO capabilities.

Possible Causes

Several potential causes have been identified for this issue:

• Hardware Limitations: The GPIO pins are designed to output low current (approximately 0.5mA), which may not be adequate for switching external devices.
• Driver Issues: The level shifters used in the carrier board may not support sufficient current output due to their automatic direction control feature, which can be sensitive to load conditions.
• Configuration Errors: Incorrect configuration of GPIO settings or PWM signals may lead to inadequate performance.
• Environmental Factors: Insufficient power supply or temperature variations could affect performance, although this is less likely given user reports.
• User Misconfigurations: Users may not be aware of necessary components such as buffer chips or current-limiting resistors that can enhance performance.

Troubleshooting Steps, Solutions & Fixes

To address the issues with GPIO output current on the Jetson Orin Nano Dev Kit, users can follow these troubleshooting steps and solutions:

1. Use a Buffer Chip:

   • Implement an 74LVC541A buffer chip between the Jetson GPIOs and the motor driver. This chip can handle up to 25mA per output, significantly improving current delivery.
   • Ensure a 100nF capacitor is placed between VCC (Pin 20) and GND (Pin 10) of the buffer chip.

2. Configuration Adjustments:

   • Verify that PWM signals are correctly configured using:

     sudo python3 /opt/nvidia/jetson-io/jetson-io.py
     

   • Ensure that unused inputs are tied to GND or VCC and unused outputs are left open.

3. Consider Alternative Drivers:

   • If issues persist, consider using a different motor driver that does not rely on optocouplers or has built-in digital isolators.

4. Testing with Different Components:

   • Test with other level shifters, such as SN74AXC8T245, which offer manual direction control and higher output current capabilities.

5. Check for Current Limiting Resistors:

   • Review the motor driver’s user manual for any requirements regarding current limiting resistors and ensure they are properly implemented.

6. Documentation and Updates:

   • Regularly check for updates or patches related to JetPack and driver support that may address GPIO performance issues.

7. Best Practices:

   • Use proper wiring techniques to minimize interference and ensure stable connections.
   • Monitor power supply conditions to ensure adequate voltage and current delivery.

8. Unresolved Aspects:

   • Users should remain aware that while these solutions may resolve many issues, there may still be hardware limitations inherent to the Jetson Orin Nano’s design that could require further investigation or alternative approaches.

By following these steps, users should be able to troubleshoot and potentially resolve issues related to inadequate GPIO current output on their Nvidia Jetson Orin Nano Developer Kit.