[ntp:questions] Using PPS

David Taylor david-taylor at blueyonder.co.uk.invalid
Fri Dec 28 12:31:27 UTC 2012


On 28/12/2012 10:00, Joshua Small wrote:
> Hi,
>
> I've just sorted this out.
>
> Although I followed the guide I linked mostly, I did read this page regarding "known issues" and used the configure flags recommended there:
> http://ml.linuxpps.org/wiki/index.php/LinuxPPS_NTPD_support
>
> That page has bad advice it appears. After recompiling with the originally recommended flags, I get the desired PPS output on ntpq.
>
> It does feel like a bug though. Clearly I missed the flags required for both driver 20 and 22 in my configure script. If I put 22 in my ntp.conf, I got an event telling me, and you know it's broken. With driver 20, it said "ok" and never did anything.
>
> David, I tried alternating 20 and 22, they both work now for me. I didn't do anything special afaik.
>
> -Josh

Good to hear you're making progress, Josh.

There is information on NTP bugs here:
   http://www.ntp.org/bugs.html

although you may have to register to file the report:
   http://bugs.ntp.org/index.cgi

I'm used to the Windows implementation of NTP, which doesn't have the 
same PPS implementation.  I guess that the Linux type 20 driver must 
call PPS support internally.  I used the type 28 ref-clock initially, as 
the GPS/PPS source I had talked TSIP (Trimble) protocol over USB (not 
serial), and I used gpsd to see that was working, and make it available 
as NMEA messages to NTP.

Likely there are many ways of skinning this cat!
-- 
Cheers,
David
Web: http://www.satsignal.eu



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