Set Hardware clock on Am335x

Nina Weber

Hello,

I am running ti-sdk-am335x-evm-06.00.00.00 on my AM335x. Now, in my application I want to display time and date, so I manually set the date with

date 102211442015.00

But after a reboot the date is reset to January 2000. So I tried to set the hardware clock to system time with

hwclock -w, but it didn't work. I can't even figure out how to set the hardware clock time to anything, it always stays the same:

root@am335x-evm:~# hwclock
Sat Jan 1 00:00:00 2000 0.000000 seconds

Could someone please help me? Thanks a lot

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi Nina,

This should be the correct procedure:
1. At kernel prompt set the system date and time:
date MMDDhhmmYYYY

2. Update the RTC:
hwclock -w

3. For verification you can read the RTC with:
hwclock -r

0 Nina Weber over 9 years ago in reply to Biser Gatchev-XID

Intellectual 445 points

Hi,
thanks for your fast response. My output is this:
root@am335x-evm:~# date 102213292015
Thu Oct 22 13:29:00 UTC 2015
root@am335x-evm:~# hwclock -w
root@am335x-evm:~# hwclock -r
Sat Jan 1 00:00:00 2000 0.000000 seconds

I don't seem to be able to change the hardware clock at all. Is there another way to do this? Or a possible way around it?

0 Biser Gatchev-XID over 9 years ago in reply to Nina Weber

TI__Guru**** 393215 points

Nina,

Do you have a 32.768kHz crystal for the AM335X RTC? Is it enabled? Or are you using an external RTC?

0 Brad Griffis over 9 years ago in reply to Biser Gatchev-XID

TI__Guru*** 125430 points

It sounds like perhaps the RTC subsystem is being reset during the board-level reset. Does your hardware properly separate RTC_PWRONRSTn from PWRONRSTn? Can you verify that RTC_PWRONRSTn is not being asserted when you reboot? Does the RTC power supply stay alive throughout the entire reboot?

0 Nina Weber over 9 years ago in reply to Brad Griffis

Intellectual 445 points

Thanks for your help. I didn't configure the board, I just use it. I got a new image for my Am355x, on which this problem is resolved. I can't tell you the difference between the two images, but it works now. Thanks again!

0 Biser Gatchev-XID over 9 years ago in reply to Nina Weber

TI__Guru**** 393215 points

Thanks for updating the thread!

0 Brad Griffis over 9 years ago in reply to Biser Gatchev-XID

TI__Guru*** 125430 points

It would be a nice contribution to the community if you could find out what was changed in the new software that solved the issue.

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Set Hardware clock on Am335x