Configuring GPIO as Wake-Up Source for Jetson Orin Nano Deep Sleep

Issue Overview

Users of the Nvidia Jetson Orin Nano Developer Kit are seeking a method to implement a deep sleep state and wake-up functionality using GPIO pins instead of the power pin. The specific use case involves putting the Orin Nano into sleep mode when there is no detection from an Ultrasonic Sensor (USS) and waking it up when the USS detects an object. Currently, the system is put to sleep using the command echo mem > /sys/power/state, and an external microcontroller sends a pulse to the power pin for wake-up. The user wants to transition from using the power pin to using GPIO for the wake-up process.

Possible Causes

1. Lack of GPIO Configuration: The GPIO pins may not be properly configured as wake-up sources in the device tree.

2. Incompatible JetPack Version: Certain JetPack versions might not support GPIO wake-up functionality or may require specific configurations.

3. Hardware Limitations: The specific Orin Nano model or custom board being used might have limitations on which GPIOs can be used as wake-up sources.

4. Incorrect Power Management Settings: The system’s power management settings may not be configured to allow GPIO wake-up from deep sleep states.

5. Software Conflicts: Existing software or drivers might be interfering with the GPIO wake-up functionality.

Troubleshooting Steps, Solutions & Fixes

1. Verify Hardware and Software Configuration:

   • Confirm whether you are using the Jetson Orin Nano Developer Kit or a custom board.
   • Identify and document the JetPack version installed on your system.

2. Enable GPIO as Wake-Up Source:

   • Refer to the NVIDIA documentation on "Enabling GPIO as a Wake-Up Source".

   • Modify the device tree to configure the desired GPIO pin as a wake-up source.

   • Example device tree modification (adjust according to your specific GPIO):

     {
         gpio@2200000 {
             wake-gpio = <&gpio TEGRA234_MAIN_GPIO(A, 0) GPIO_ACTIVE_LOW>;
         };
     }
     

3. Update Device Tree:

   • Compile the modified device tree:

     dtc -I dts -O dtb -o /boot/tegra234-p3767-0000-p3509-a02.dtb /boot/tegra234-p3767-0000-p3509-a02.dts
     

   • Reboot the system for changes to take effect.

4. Configure Power Management:

   • Ensure the system is configured to enter the correct sleep state:

     echo mem > /sys/power/state
     

   • Verify that the chosen GPIO is set as a wake-up source:

     cat /sys/devices/platform/gpio@2200000/gpio/gpiochip0/events/wakeup
     

5. Test GPIO Wake-Up:

   • Use a simple script to monitor the GPIO state and trigger wake-up:

     import RPi.GPIO as GPIO
     import time
     
     GPIO.setmode(GPIO.BOARD)
     GPIO_PIN = 18  # Adjust to your specific GPIO pin
     GPIO.setup(GPIO_PIN, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
     
     while True:
         if GPIO.input(GPIO_PIN):
             print("Wake-up signal detected!")
         time.sleep(0.1)
     

6. Troubleshoot Unresponsive Wake-Up:

   • Check system logs for any errors related to power management or GPIO:

     journalctl -b | grep -i "gpio\|power\|wake"
     

   • Verify that the GPIO pin is not being used by other processes:

     gpio readall
     

7. Consult NVIDIA Developer Forums:

   • If issues persist, share your full device tree and JetPack version on the NVIDIA Developer Forums for more specific assistance.

8. Consider Alternative Wake-Up Methods:

   • If GPIO wake-up proves challenging, explore other wake-up methods supported by the Jetson Orin Nano, such as RTC alarms or network wake-on-LAN.

Remember to thoroughly test the wake-up functionality in various scenarios to ensure reliability in your project’s specific use case.