linux-mips
[Top] [All Lists]

Re: Power loss and system time when not having a battery backed RTC

To: Attila Kinali <attila@kinali.ch>
Subject: Re: Power loss and system time when not having a battery backed RTC
From: Markus Gothe <markus.gothe@27m.se>
Date: Wed, 28 Mar 2007 16:47:48 +0200
Cc: linux-mips@linux-mips.org
In-reply-to: <20070328163914.b7187fcb.attila@kinali.ch>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20070328163914.b7187fcb.attila@kinali.ch>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Icedove 1.5.0.10 (X11/20070307)
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

Attila Kinali wrote:
> Moin,
>
> I have a little bit more general question than usual. I have here a
> system that should be deployed in Joe Average's house as a small
> appliance. While it is powered it will gather information and store
> them on its flash.
>
> Now, this system does not contain a battery backed RTC (not enough
> space) and thus does not know what date/time it is after boot. At a
> later time the device will be able to get a time quote from a time
> server using a wireless connection. But as the wireless connection
> is triggered by a user action, it can happen hours after boot. This
> means that there is a quite long period whithin which the device
> does not know what time it is and hence assumes it's 1970.
>
> My problem lies now in the back jumps that the device makes, when
> unplugged and replugged. On the filesystem there will be files from
> 2007, while the system still thinks it's 1970.
>
> How do you handle this issue with the back jumps, if you cannot
> stick in a batter backed RTC?
>
>
> Thanks for your help
>
> Attila Kinali
Be creative or use the battery, you could for example set a timestamp
in a file at shutdown and use it to set the date on power up, alas
this would be incorrect, so go for the battery.

- --
_______________________________________

Mr Markus Gothe
Software Engineer

Phone: +46 (0)13 21 81 20 (ext. 1046)
Fax: +46 (0)13 21 21 15
Mobile: +46 (0)73 718 72 80
Diskettgatan 11, SE-583 35 Linköping, Sweden
www.27m.com
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (GNU/Linux)

iD8DBQFGCoAR6I0XmJx2NrwRCNbtAJ9jMBSxe0WOvv3o844TCqbHKbmgOwCeNmOR
Uot4Bwa7+EYx3/8b7h4bVcM=
=X6k4
-----END PGP SIGNATURE-----


<Prev in Thread] Current Thread [Next in Thread>