Real Time Clock Questions (DS 1307)

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Real Time Clock Questions (DS 1307)

Postby Balzy » Mon Mar 30, 2015 8:34 pm

Hello Archlinux ARM community!
I'm a proud user of Arch ARM and I'm running it on a small raspberry server.

I've decided to build a ds1307 I2C hardware clock to have consistent log timestamps between each reboot (and for fun of course).
All guides / instructions I've found around boil down to:

1. Install i2c-tools
2. Enable i2c-bcm2708 and i2c-dev modules
3. Enable rtc-ds1307 module
4. Run echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device

This allow me to read from/write to/ set the RTC within user land. I read in a couple of topic around the web (I'm sorry I cannot find those pages any more) that it is possible to read the RTC immediately at boot from kernel land. By the way that article wasn't very useful, it didn't mention how to do it and I can't find anything else online. Can you give me any hints?

I'd also like to achieve something like this:

1. System boots and loads immediately time from RTC
2. System checks time periodically during running time and sync both RTC and system time with internet time

It would allow me to keep the RTC updated in case a shut-down or a reboot occurs at any time.

Any help in achieving this is very appreciated, I know how a Linux system work but I've never "messed up" with system time, ntpd and hwclock, I just need few hints to get things run the right way.

Regards,
Stefano
Balzy
 
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Joined: Mon Mar 30, 2015 6:35 pm

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