Interrupt-capability of GPIOs

Issue Overview

The discussion revolves around the interrupt capability of General Purpose Input/Output (GPIO) pins on the Nvidia Jetson Orin Nano Dev board. Users, particularly a user named Sven, are seeking clarification on whether all GPIOs, including both "native" GPIOs (GPIO00 to GPIO14) and those designated for secondary functions (e.g., GPIO3_PA.xx to GPIO3_PZ.xx), can trigger hardware interrupts.

Symptoms and Context

• Symptoms: Users are uncertain if specific GPIOs can generate hardware interrupts, which is critical for their custom carrier board designs.
• Context: The issue arises during the design phase when users need to understand the capabilities of the GPIOs for implementing features such as CAN communication.
• Hardware/Software Specifications: The discussion references the Pinmux Config Template, which outlines the functionality of various GPIOs.
• Frequency: This issue appears to be a common point of confusion among users designing custom boards.
• Impact: The inability to confirm interrupt capabilities could hinder development and functionality in projects requiring multiple GPIOs.

Possible Causes

• Hardware Incompatibilities: Misunderstandings regarding which GPIOs can serve dual functions might lead to incorrect assumptions about their capabilities.

• Software Bugs or Conflicts: There may be inconsistencies in documentation or firmware that do not clearly define interrupt capabilities for all GPIOs.

• Configuration Errors: Users might not be configuring the GPIOs correctly in their applications, leading to failures in triggering interrupts.

• Driver Issues: Outdated or incompatible drivers may not support interrupt functionality for certain GPIOs.

• User Errors or Misconfigurations: Lack of clarity in documentation could lead users to misconfigure their setups, resulting in unexpected behavior.

Troubleshooting Steps, Solutions & Fixes

Step-by-Step Troubleshooting

1. Verify Documentation:

   • Review the Pinmux Config Template thoroughly to understand which GPIOs are designated for interrupt capability.

2. Check Firmware Version:

   • Ensure that you are using the latest firmware version for the Jetson Orin Nano. Update if necessary.

3. Test GPIO Configuration:

   • Use a simple test script to configure each GPIO for interrupt handling. Example code snippet in Python:

   import Jetson.GPIO as GPIO
   import time
   
   # Set up GPIO pin
   pin = 12  # Replace with your specific pin number
   GPIO.setmode(GPIO.BOARD)
   GPIO.setup(pin, GPIO.IN, pull_up_down=GPIO.PUD_UP)
   
   def callback(channel):
       print("Interrupt detected!")
   
   # Add event detection
   GPIO.add_event_detect(pin, GPIO.FALLING, callback=callback)
   
   try:
       while True:
           time.sleep(1)
   except KeyboardInterrupt:
       print("Exiting...")
       GPIO.cleanup()
   

4. Isolation Testing:

   • Test each type of GPIO individually to determine if they can trigger interrupts when configured correctly.

5. Consult Community Resources:

   • Engage with forums or community discussions for additional insights or similar experiences from other users.

Recommended Solutions

• Use All Available GPIOs: Based on community feedback, all GPIOs on the Jetson Orin Nano should have similar interrupt capabilities as those on other Jetson models. Thus, it is generally safe to assume that they can be used interchangeably.

• Clarify Terminology: Understand that terms like "native" and "secondary function" are often used interchangeably in this context. Focus on practical testing rather than terminology.

Preventive Best Practices

• Regularly update firmware and drivers to ensure compatibility and access to new features.

• Maintain clear documentation within projects regarding which GPIOs are used and their intended functions to avoid future confusion.

Unresolved Aspects

While many users have successfully utilized various GPIOs for interrupts, there remains some ambiguity regarding specific configurations and potential limitations based on individual setups. Further investigation may be needed into particular use cases or hardware configurations that deviate from standard practices.