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Re: [gpsd-dev] PPS not showing in gpsmon/gpsd on RPi 3


From: Eric S. Raymond
Subject: Re: [gpsd-dev] PPS not showing in gpsmon/gpsd on RPi 3
Date: Mon, 25 Apr 2016 09:30:28 -0400
User-agent: Mutt/1.5.23 (2014-03-12)

Hal Murray <address@hidden>:
> 
> address@hidden said:
> > Nothing confusing to gpsd at all.  gpsd is just reporting there is no PPS or
> > PPS available on that serial line.  Which is exactly true.  Maybe the
> > message could be clearer. 
> 
> Just to add to the confusion....
> 
> There are two cases of "no PPS".  One is that nothing is wired to that pin.  

Right.  We know this isn't the problem as ppstest can see RFC2783 events through
.dev/pps0

> The other is that everything is wired up correctly, but the GPS device is 
> smart enough to mask off the PPS when it isn't valid, for example when first 
> powered on and it isn't listening to any satellites yet.

I can see by the blinkenlight that the HAT has a fix.

> After you get going, there are still two cases when things stop working.  Did 
> rain or whatever cause the number of satellites the receiver can hear to fall 
> too low, or did the cable get unplugged?

No, I can check that by seeing fixes with gpsmon.

Currently leaning towards the theory that there's a previously undiagnosed
race conedition in /de/pps opening.
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>



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