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

[Markus Gothe <markus.gothe@27m.se>]

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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
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