Raspberry Pi hardware real-time-clock?

[Oliver Grawert]

hi,
On Mi, 2016-12-28 at 16:40 +0000, roger peppe wrote:
> Hi,
> 
> Not sure if this is the right place to ask this question - apologies
> if not.
> 
> I need a hardware RTC on my Raspberry Pi model B and I have
> acquired one of these https://www.abelectronics.co.uk/p/52/RTC-Pi-Plu
> s
> 
> I'm running a reasonably recent version of Ubuntu Core with snappy
> version 2.18.1.
> 
> What's the best way of adding this to my Pi so that it gets the time
> on bootstrap and keeps it in sync? The instructions I've found rely
> on changing configuration files that are on the read-only filesystem,
> such as /etc/init.d/hwclock.sh. I'd be happy to make a new snap
> to do this if that's what's needed.
> 
> Thanks for any pointers,
> 

i2c is enabled by default, you will likely have to edit
/boot/uboot/config.txt to additionally enable the i2c-rtc and ds1307
device trees, like:

dtoverlay=i2c-rtc,ds1307

on reboot i would expect the rtc-ds1307 module to be loaded
automatically and the hwclock boot job to set/get the hwclock time...

if you run into any issues with this, please make sure to file the
respective bugs.

i dont think anyone of us has yet used a battery driven rtc module to
actually verify it works, so your feedback will be very appreciated ...

ciao
	oli

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