How to Install an RTC Battery on the Jetson Orin Nano

Issue Overview

Users are experiencing difficulties in setting up a Real-Time Clock (RTC) on the Jetson Orin Nano Developer Kit. The main symptoms include the RTC resetting between power cycles, indicating that the RTC battery is not functioning as expected. This issue arises during the installation of an RTC battery holder, specifically when users attempt to connect a CR1220 battery holder to the designated pins on the board. Users have reported that despite following documentation and verifying connections, the RTC does not retain time after power loss. The problem appears to be consistent among multiple users, significantly impacting their ability to maintain accurate timekeeping for applications reliant on RTC functionality.

Context

• Hardware Specifications: Users mention using a CR1220 battery holder and a 1K ohm resistor near the J3 connector on the Jetson Orin Nano.
• Software Context: Issues arise during hardware setup, particularly when configuring the RTC.
• Frequency: The problem seems prevalent among users attempting similar setups, suggesting a common underlying issue.
• User Experience Impact: The inability to maintain time across power cycles hinders projects that depend on accurate timing.

Possible Causes

1. Hardware Incompatibilities or Defects: The absence of a pre-installed connector or housing for the RTC battery may lead to improper connections.
2. Configuration Errors: Incorrect installation of components like resistors could prevent proper functionality.
3. Driver Issues: Software drivers responsible for interfacing with the RTC may not be correctly configured or updated.
4. Environmental Factors: Power supply inconsistencies or temperature variations could affect RTC performance.
5. User Errors or Misconfigurations: Misunderstanding of pin configurations and component placements may lead to installation errors.

Troubleshooting Steps, Solutions & Fixes

1. Verify Connections:

   • Ensure that pin 1 (power) and pin 2 (ground) are correctly identified and connected.
   • Use a multimeter to check voltage across the pins; it should be approximately +3 volts.

2. Install Correct Resistor:

   • Users have reported success with a 560 ohm resistor (ERJ-2BQJR56X). If a different resistor was used, replace it with this specific value.

3. Check Documentation:

   • Refer to the Jetson Orin Nano Developer Kit Carrier Board Specification for detailed diagrams and component placements. Specifically, review pages that indicate resistor placements and pin configurations.

4. Use External RTC via I2C:

   • If internal RTC setup fails, consider using an external RTC module connected via I2C as an alternative solution.

5. Modify Udev Rules:

   • Ensure that /dev/rtc is correctly mapped to /dev/rtc0 by modifying udev rules if necessary.

6. Firmware and Driver Updates:

   • Ensure that the latest firmware is installed on the Jetson Orin Nano by using NVIDIA SDK Manager to flash JetPack 5.x or later versions.

7. Testing with Different Configurations:

   • Test with another Jetson Orin Nano board if available, to rule out hardware defects.

8. Documentation References:

   • For further assistance, refer to NVIDIA’s official documentation for setup instructions and troubleshooting tips related to RTC configurations.

Code Snippets and Commands

• To check device mapping:

  ls /dev/rtc*
  

• To update udev rules:

  sudo nano /etc/udev/rules.d/99-rtc.rules
  

• To shut down safely before making hardware changes:

  sudo shutdown -h now
  

Best Practices

• Always double-check component specifications before installation.
• Keep firmware updated to ensure compatibility with new features and fixes.
• Consider documenting your setup process for future reference or community sharing.

Unresolved Aspects

Some users still report inconsistencies in RTC functionality despite following these steps, indicating potential undiscovered issues with specific board revisions or configurations that may require further investigation from NVIDIA support or community forums.