GPIO Configuration Issues on Nvidia Jetson Orin Nano Custom Board

Issue Overview

Users are experiencing difficulties with GPIO configuration and functionality on a custom board based on the Nvidia Jetson Orin Nano Dev board. The main symptoms include:

• Inability to change GPIO pin output levels despite modifying pinmux configurations
• GPIO pins not responding to value changes in sysfs
• Issues observed on both custom and DevKit boards
• Problems persist across multiple GPIO pins (PG.06, PN.01, PQ.06, PZ.07, PY.02, PY.03)
• Voltage measurements show no change when attempting to set GPIO values

The issue occurs during setup and testing of GPIO functionality, impacting the ability to control external hardware through these pins. This problem significantly hinders the development and integration of custom hardware solutions using the Jetson Orin Nano platform.

Possible Causes

1. Incorrect Pinmux Configuration: The pinmux settings may not be properly applied or may be incorrect for the desired GPIO functionality.

2. Sysfs GPIO Interface Issues: There might be problems with the sysfs GPIO interface, especially considering the transition from JetPack 5 to JetPack 6.

3. Hardware Design Flaws: The custom board’s circuitry might have issues preventing proper GPIO operation, such as incorrect pull-up/pull-down resistors or other components affecting the GPIO lines.

4. Kernel Configuration Problems: The kernel may not be properly configured to support GPIO sysfs or other required features.

5. Driver Issues: There could be problems with the GPIO driver implementation or compatibility with the custom board.

6. Bootloader Configuration: The bootloader might not be correctly applying the modified device tree and pinmux settings.

7. Power Management Issues: The system’s power management settings might be affecting GPIO functionality.

Troubleshooting Steps, Solutions & Fixes

1. Verify Pinmux Configuration:

   • Use the method described in the Nvidia documentation to read pinmux registers and confirm your settings.
   • Command to check pinmux (replace ADDRESS with the appropriate register address):

     sudo busybox devmem ADDRESS 32
     

2. Correct GPIO Sysfs Usage:

   • Ensure you’re using the correct sysfs commands for your JetPack version.
   • For JetPack 6, use the following commands:

     echo 389 > /sys/class/gpio/export
     echo out > /sys/class/gpio/PG.06/direction
     echo 1 > /sys/class/gpio/PG.06/value
     echo 0 > /sys/class/gpio/PG.06/value
     

3. Isolate Hardware Issues:

   • Test the same GPIO configuration on a DevKit board to rule out custom hardware problems.
   • Use an oscilloscope or multimeter to measure GPIO pin voltages directly on the board.

4. Check Kernel Configuration:

   • Verify that GPIO_SYSFS is enabled in the kernel configuration.
   • Review the kernel log for any GPIO-related errors:

     dmesg | grep -i gpio
     

5. Inspect Device Tree:

   • Review the generated device tree file (tegra234-mb1-bct-gpio-p3767-dp-a03.dtsi) for correct GPIO configurations.
   • Ensure the bootloader is using the updated device tree by reflashing:

     ./flash.sh -c bootloader/generic/cfg/flash_t234_qspi.xml $BOARD nvme0n1p1
     

6. Verify GPIO Debug Information:

   • Check the GPIO debug output for correct status:

     cat /sys/kernel/debug/gpio
     

7. Test Multiple GPIO Pins:

   • Try configuring and testing different GPIO pins (e.g., PN.01, PQ.06, PZ.07, PY.02, PY.03) to identify any pin-specific issues.

8. Consult Nvidia Documentation:

   • Review the Jetson Module Adaptation and Bring-Up guide for Orin NX/Nano series.
   • Download and refer to the Orin Series SoC Technical Reference Manual for detailed hardware specifications.

9. Check for Software Updates:

   • Ensure you’re using the latest JetPack 6 release and BSP (Board Support Package) for your custom board.

10. Analyze Power Management:

    • Investigate if power management settings are affecting GPIO functionality:

      sudo cat /sys/kernel/debug/tegra_pmc/rail_stats
      

If the issue persists after trying these steps, consider reaching out to Nvidia developer support or consulting with a hardware engineer to review the custom board design, especially focusing on the GPIO circuitry and power distribution.