[Voyage-linux] Re: PPS kernel patches

Thu Dec 27 23:17:11 HKT 2007

I have to echo Clark's comments. 

I did solder the PPS output of my RX (no-name $5 board from ebay) to pin
1 DCD. This is pretty common on most OEM boards.

Like Clark I'm looking to build an appliance that "just works".

Thanks again for looking into this Punky!

Mark

On Wed, 2007-12-26 at 22:42 -0800, Clark Hartsock wrote:
> I have been using Garmin GPS25 and GPS18 gps receivers, both of which
> have rs232 compatible outputs. They also have a hard wired 1pps port
> that I connected to the DCD pin (pin 1 on a 9 pin) of the connector.
> Yes, I did need to do some soldering.
> 
> These work well on the big bells an whistles linux distros, but my
> goal is an appliance that "just works" when you turn it on. The work
> on Voyage is greatly appreciated by me because it is perfect for this
> goal.
> 
> I haven't followed the kernel very closely to see if the pps patch has
> been added to the source tree. But the links you show are for the
> kernel. ntpd has the interface already built-in to accept pps and
> serial data - you won't need to patch it.
> 
> Thanks!
> 
> Clark
> kr6au
> 
> On Dec 26, 2007 5:34 PM, Kim-man 'Punky' TSE <punkytse at punknix.com> wrote:
> > Mark and Clark,
> >
> > Don't get me wrong, but I spend a few minutes on the links below and I
> > found that it is indeed for 2.0/2.2/2.4 kernel!?
> >
> > Luckily I find this one.
> >     http://wiki.enneenne.com/index.php/LinuxPPS_support
> > and patches here:
> >     http://ftp.enneenne.com/pub/misc/linuxpps/patches/
> >
> > Including patch is OK, but patching ntpd may be a issue ... (for me).
> >
> > Instead, you need special equipment for getting PPS signal, at least you
> > need soldering things.  What GPS device you usually uses for 1PPS?
> >
> > Regards,
> > Punky
> >
> > Mark Phillips wrote:
> > > You need to look at the NTP sources. These contain a kernel patch. If I
> > > understand it correctly, GPSD and others pick up the 1PPS via the kernel
> > > (usually connected to the DCD pin on the serial port).
> > >
> > > They are available here ftp://ftp.kernel.org/pub/linux/daemons/ntp/PPS/
> > > and a rough howto is available here http://etienne.favey.ch/ntp/
> > >
> > > Thanks very much for looking at this!
> > >
> > > Mark
> > >
> > > On Mon, 2007-12-24 at 09:27 +0800, Kim-man 'Punky' TSE wrote:
> > >
> > >> Hi ,
> > >>
> > >> But where can I get the 1PPS patch for Linux and instruction?  As far as
> > >> I read gpsd documentation, it indeed support 1PPS as long as you have
> > >> the proper equipment.
> > >>
> > >> What is the different between gpsd support for 1PPS and the 1PPS patch
> > >> for the time server?
> > >>
> > >> Regards,
> > >> Punky
> > >>
> > >> Mark Phillips wrote:
> > >>
> > >>> Any thoughts/comments on this Punky?
> > >>>
> > >>>
> > >>>
> > >>> On Mon, 2007-12-10 at 14:33 -0500, Mark Phillips wrote:
> > >>>
> > >>>
> > >>>> I have mine setup in a similar way but it is not a true time server in
> > >>>> that because of the lack of a disciplining kick on a regular basis it is
> > >>>> able to drift between time updates.
> > >>>>
> > >>>> The problem with NMEA time strings is that they tend to come in a
> > >>>> cluster and not at all every second or 3 seconds or 5 seconds. They come
> > >>>> along whenever the GPS processor has time to spit them out.
> > >>>>
> > >>>> The 1PPS pulse from the GPS system is not derived from the decoded data
> > >>>> but rather is an inherant component of the GPS signal along with the
> > >>>> 10KHz pulse and thus is more reliable.
> > >>>>
> > >>>> I'd still like to see a 1PPS patched kernel particularly as it would
> > >>>> then allow for connections to things like Frequency Standards and LORAN
> > >>>> RX's etc. Heck, one could even connect it up to the mains after a very
> > >>>> simple signal divider (trick used on clock radios etc) is added.
> > >>>>
> > >>>> Mark
> > >>>>
> > >>>> On Thu, 2007-12-06 at 19:24 +0800, Kim-man 'Punky' TSE wrote:
> > >>>>
> > >>>>
> > >>>>> Hi guys,
> > >>>>>
> > >>>>> Forget to mention, I have setup voyage attached to Garmin GPS18/USB and
> > >>>>> get NTP time sync'd.  Of course, this device is not PPS-capable, but it
> > >>>>> works without any patch to the kernel and NTP daemon.   See my blog article:
> > >>>>>
> > >>>>>     http://www.punknix.com/?q=node/116
> > >>>>>
> > >>>>> Regards,
> > >>>>> Punky
> > >>>>>
> > >>>>> Mark Phillips wrote:
> > >>>>>
> > >>>>>
> > >>>>>> Now I think about it, updating the gpsd package would also be useful for
> > >>>>>> this purpose.
> > >>>>>>
> > >>>>>> FYI, my NTP server is running Voyage on a Neoware N3000 thin client
> > >>>>>> (ebay $20). It has a 300MHz via processor in it as well as an IDE
> > >>>>>> interface which is now running a CF card. The GPS RX plugs into ttyS0
> > >>>>>> and I'm running gpspipe on ttyS1 to allow my Nixie tube clock to correct
> > >>>>>> itself.
> > >>>>>>
> > >>>>>> Mark
> > >>>>>>
> > >>>>>> On Fri, 2007-11-30 at 05:10 +0000, Clark wrote:
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>> Mark Phillips <g7ltt at ...> writes:
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>> Hi all,
> > >>>>>>>>
> > >>>>>>>> Is there anywhere that I can register a feature request for adding PPS
> > >>>>>>>> to the kernel for use in NTP apps? This would be really handy I think.
> > >>>>>>>>
> > >>>>>>>> Thanks
> > >>>>>>>>
> > >>>>>>>> Mark
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>>>
> > >>>>>>> I would really like that too!
> > >>>>>>>
> > >>>>>>> I have been using Voyage to try to create an NTP appliance  'cause the
> > >>>>>>> commercial ones are WAY beyond my budget!
> > >>>>>>>
> > >>>>>>> I appreciate the work on Voyage so far!
> > >>>>>>>
> > >>>>>>> Thanks!
> > >>>>>>>
> > >>>>>>>
> > >>>>>>> _______________________________________________
> > >>>>>>> Voyage-linux mailing list
> > >>>>>>> Voyage-linux at list.voyage.hk
> > >>>>>>> http://list.voyage.hk/mailman/listinfo/voyage-linux
> > >>>>>>>
> > >>>>>>>
> > >>>>>>>
> > >>>>>
> > >>>>>
> > >>
> >
> >
> > --
> > Regards,
> > Punky
> >
> > Voyage Solutions (http://solution.voyage.hk)
> > * Embedded Solutions and Systems
> >   - Mesh Networking, Captive Portal, IP Surveillance, VoIP/PBX
> >   - Network Engineering, Development Platform and Consultation
> >
> >
> >
> >
-- 

Mark Phillips, G7LTT/NI2O
Randolph, NJ