RTC with battery connected does not survive power cycle

Robotics & Edge Computing Jetson Systems Jetson AGX Orin
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1

I have been working with some Orin dev kits and have been having issues with the real time clock. Our systems will not be connected to the network, As long as I have set the clock and power has stayed on, it keeps time just fine. If I remove system power, the time is gone and I have to reset it again. We also have the RTC CMOS battery connected and checked to see if it is not drained. I’d love to hear from anyone who has had luck getting the time to be persistent.

Jetpack version:
Package: nvidia-jetpack
Version: 5.1.1-b56
Priority: standard
Section: metapackages
Maintainer: NVIDIA Corporation
Installed-Size: 199 kB
Depends: nvidia-jetpack-runtime (= 5.1.1-b56), nvidia-jetpack-dev (= 5.1.1-b56)
Homepage: Jetson - Embedded AI Computing Platform | NVIDIA Developer
Download-Size: 29.3 kB
APT-Manual-Installed: yes
APT-Sources: https://repo.download.nvidia.com/jetson/common r35.3/main arm64 Packages
Description: NVIDIA Jetpack Meta Package

timedatectl status
Local time: Wed 2023-03-15 17:57:59 CDT
Universal time: Wed 2023-03-15 22:57:59 UTC
RTC time: Thu 1970-01-01 07:54:26
Time zone: America/Chicago (CDT, -0500)
System clock synchronized: no
NTP service: inactive
RTC in local TZ: no

Also, for the version of Jetpack I have, is it necessary for /dev/rtc(symbolic linked with /dev/rtc1) or rct0?

Instructions on getting the rtc to work even after powercycles when not connected to the internet will be highly appreciated.

3

Have reference to below topic.

4

Hi Shane,

Thank you for the response. I just want to confirm to see if all 3 steps are required to get the rtc with no network connection and the battery connected: build kernel with CONFIG_RTC_HCTOSYS_DEVICE option, edit 50-udev-default.rules, and modify symbolic link.
If yes, Can your reference on how to build the kernel and deploy a new kernel be patched/updated in an already deployed unit without needing to blow away the existing file system?

5

Please reference to below document for kernel customized.

https://docs.nvidia.com/jetson/archives/r35.3.1/DeveloperGuide/text/SD/Kernel.html

6

Thank you. This worked.

8

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