[ntp:questions] Timing issue with Linux and kernel PPS?

David Taylor david-taylor at blueyonder.co.uk.invalid
Sun Nov 18 07:22:29 UTC 2012

On 17/11/2012 21:57, Uwe Klein wrote:
> David Taylor wrote:
>> I'm seeing behaviour on rebooting a Raspberry Pi Linux system which is
>> stopping the PPS signal getting through to NTP.  It seems that the GPS
>> device does not emit any pulses on the PPS line for some time after it
>> has been powered up.  This I understand and it's the time taken for a
>> good enough lock to be acquired.
>> However, it seems that if the PPS part of the kernel hasn't seen a
>> transition, it does not create the pps device at least until the first
>> transition is seen.  The delay seems to be some 133 seconds here:
>> Does this seem possible, and how might it be fixed?
> helps?:
>      http://www.raspberrypi.org/phpBB3/viewtopic.php?f=41&t=1970&start=150
> uwe

Thanks, uwe, but I'm not sure that it does - perhaps I cannot see the 
wood for the trees!  I have seen that article before, but I am very new 
to Linux.  I /am/ seeing the PPS start, but it needs a reboot before NTP 
sees it.  Am I correct in thinking that the 133 seconds delay before 
"PPS line discipline registered" is significant in this problem?

Which part of the article or what keyword should I be looking for?
Web: http://www.satsignal.eu

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