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The problem as logs follow.
The Orin develop kit will reset the rtc after reboot.
I am sure, I have inset a RTC battery, which voltage is 3.0 V.
nvidia@orin:~$ cat /etc/nv_tegra_release
R35 (release), REVISION: 1.0, GCID: 31346300, BOARD: t186ref, EABI: aarch64, DATE: Thu Aug 25 18:41:45 UTC 2022
nvidia@orin:~$ sudo dmesg | grep DTB
[sudo] password for nvidia:
[ 0.003912] DTB Build time: Aug 10 2022 20:31:40
nvidia@orin:~$ sudo dmesg | grep DTS
[ 0.003900] DTS File Name: /dvs/git/dirty/git-master_linux/kernel/kernel-5.10/arch/arm64/boot/dts/…/…/…/…/…/…/hardware/nvidia/platform/t23x/concord/kernel-dts/tegra234-p3701-0000-p3737-0000.dts
nvidia@orin:~$ uname -a
Linux orin 5.10.104-tegra #1 SMP PREEMPT Wed Aug 10 20:17:07 PDT 2022 aarch64 aarch64 aarch64 GNU/Linux
nvidia@orin:~$ date
Thu 21 Apr 2022 08:58:36 AM EDT
nvidia@orin:~$ date -s “2022-09-19 17:23:00”
date: cannot set date: Operation not permitted
Mon 19 Sep 2022 05:23:00 PM EDT
nvidia@orin:~$ sudo date -s “2022-09-19 17:23:00”
Mon 19 Sep 2022 05:23:00 PM EDT
nvidia@orin:~$ sudo hwclock -w -f /dev/rtc1
[sudo] password for nvidia:
nvidia@orin:~$ sudo hwclock -r -f /dev/rtc1
2022-09-19 17:23:59.442610-04:00
nvidia@orin:~$ sudo hwclock
hwclock: select() to /dev/rtc0 to wait for clock tick timed out
nvidia@orin:~$ timedatectl **
** Local time: Mon 2022-09-19 17:25:10 EDT **
** Universal time: Mon 2022-09-19 21:25:10 UTC **
** RTC time: Mon 2022-09-19 21:25:10 **
** Time zone: America/New_York (EDT, -0400)
System clock synchronized: no **
** NTP service: inactive **
** RTC in local TZ: no
nvidia@orin:~$ sudo reboot
After reboot. … the RTC time was reset to “Thu 1970-01-01 00:02:04”
How can I fixed it? The develop kit can’t always connet to network.
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nvidia@orin:~$ date
Thu 21 Apr 2022 08:55:58 AM EDT
nvidia@orin:~$ timedatectl
** Local time: Thu 2022-04-21 08:56:05 EDT **
** Universal time: Thu 2022-04-21 12:56:05 UTC **
** RTC time: Thu 1970-01-01 00:02:04 **
** Time zone: America/New_York (EDT, -0400)**
System clock synchronized: no **
** NTP service: inactive **
** RTC in local TZ: no