Tx2 rtc

Autonomous Machines Jetson & Embedded Systems Jetson TX2
#1

hello,all

I have a questions about TX2 rtc. from the OEM file, I know that VDD_RTC pin connects the backup cell for BPMP RTC. in /dev/ path，I see rtc0 and rtc1. rtc0 is BPMP RTC，rtc1 is rtc@c2a0000. so both of the two rtc work, is that right? and which is the default system rtc? when the carrier board poweroff, only the BPMP RTC alive, right ?

#2

Yes, both of them are working. Current RTC1 should be the default.
Both are alive if the adapter not remove.

#3

ok thank you.
you mentioned that"Both are alive if the adapter not remove.", but when remove the adapter only the rtc0 alive. so you then device power again ,will the system check the rtc0 time and set as system clock ?

will the system make the two rtc time sync?

how to change the defaut from rtc1 to rtc0? in /dev i see that rtc present as a link of rtc1, so is that the key to set default system rtc?

is there some files to help make the rtc part clearly ?

#4

You can just disable the RCT1 by change the status in the device tree.

    rtc@c2a0000 {
            compatible = "nvidia,tegra18-rtc";
            reg = <0x0 0xc2a0000 0x0 0x100>;
            interrupt-parent = <0x3a>;
            interrupts = <0x0 0xa 0x4>;
            status = "okay";
    };
#5

thank you

I suggest could you give more information as I list in #3, plz, thank you!

#6

Below link should help.

https://unix.stackexchange.com/questions/246605/how-can-the-link-target-of-dev-rtc-be-changed

#7

Hi,

can you please explain how these two rtc time sync after device power up ?
and why there are two rtc used in board ?

1 Like
#8

  1. in my opinion， you can use ntp to sync throught net.

  2. one is from tegra ,another is from max77620

#9

Thank you for reply,

Is it possible or is there any other way to sync rtc if board is not connected to wifi or net ?

#10

I suppose you have gps module in your board, so you can you use ntp service and gps time is the source

#11