Using Real Time clock overlay

[zacha...@gmail.com]

I am trying to use a RTC click overlay. I installed the file in uEnv.txt, however I don't know how to utilize the RTC. Is there some way to set the time and use it as the hardware time so that every time the pocketbeagle boots it uses the RTC time?

[John Syne]

There is a very good book that explains everything you will need in embedded systems using Linux. I has a complete chapter on RTC.

Linux Device Drivers Development by John Madieu, published by Packt Publishing 2017.

This book doesn’t cover BBB directly, but it covers all Linux subsystems, such as SPI, I2C, RTC, DMA, etc

If you are looking for a book that covers BBB and the build cycle and root file system, then this book is very helpful:

Mastering Embedded Linux Programming - Second Edition by Chris Simmons, published by Packt Publishing 2017.

These two books will get you up and running so you are able to help yourself. I wish I had these books 10 years ago. These are the only two books that deal with the latest kernels and Device Tree. 

Regards,

John

On Feb 23, 2018, at 2:35 PM, zacha...@gmail.com wrote:

I am trying to use a RTC click overlay. I installed the file in uEnv.txt, however I don't know how to utilize the RTC. Is there some way to set the time and use it as the hardware time so that every time the pocketbeagle boots it uses the RTC time?

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[Robert Nelson]

So one thing the RTC click overlays does, it swap's the am335x rtc
(normally found on /dev/rtc0) with the click RTC (which would normally
be /dev/rtc1)

So as long as you have any network plugged in, systemd-timesyncd will
pretty much properly set /dev/rtc0 for you..

ARCh has a good doc here:

https://wiki.archlinux.org/index.php/time#Set_system_clock

Regards,

--
Robert Nelson
https://rcn-ee.com/