GPS as a source of time like NTP

Mike (mwester) mwester at
Sun Jul 27 04:25:28 CEST 2008

Joerg Reisenweber wrote:
> Am So  27. Juli 2008 schrieb Daniel Willmann:
>> Hi,
>> On Sat, 26 Jul 2008 19:42:43 -0500
>> "Dale Schumacher" <dale.schumacher at> wrote:
>>> On Sat, Jul 26, 2008 at 6:28 PM, Daniel Willmann
>>> <daniel at> wrote:
>>>> Yeah, currently a signal is emitted if the current
>>>> location/accuracy/whatever packet contains a different value than
>>>> before. So If nothing changes you wont get a Signal either. The one
>>>> exception is time because I don't want to send that every second for
>>>> nothing. The idea at the moment is to just send a TimeChanged signal
>>>> once as soon as the time is valid. After that you can request the
>>>> time if you so desire.
>>> Is the GPS time used as a source for the system, like an NTP server?
>> There's no code for it yet, but yeah, that is being taken into
>> consideration. Basically I want to send a TimeChanged signal once after
>> I got the valid time from GPS (and not every second as gypsy specifies
>> as that is just wasting resources - although that probably matters if
>> we really route accelerometer through dbus...) and whenever a program
>> asks for it via a method.
>> Then you would have a program listening on dbus for the TimeChanged
>> signal and set the system clock (and rtc) according to that.
>>> That seems like it would be a very useful option.  It would take
>>> advantage of the special capabilities of the FreeRunner beyond a
>>> typical Linux box.
>> That and auto timezone selection based on your location will be some
>> nice features, yes.
>> Regards,
>> Daniel Willmann
> please consider using ntpd. There should be standard "modules" for using GPS 
> for a timeserver.
> see:
> man ntpd
> xntp-doc
> /etc/ntp.conf
> /jOERG

ntpd should be an option, I agree -- but it's rather heavyweight for
such a simple task.  Those who need micro-second accuracy, or need the
freerunner to be a time-source for other systems will probably not be
majority of users; let's save space in flash and more importantly, lets
save some RAM for other apps.

Mike (mwester)

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