Re: [gpsd-users] gpsd:WARN: PPS TIOCMIWAIT returns unchanged state, ppsmonitor sleeps 10

[Gary E. Miller]

Yo folkert!

On Tue, 2 Jul 2013 20:36:56 +0200
folkert <address@hidden> wrote:

> > > Ok I added an extra serial card but that did not help.
> > Too bad, but not unexpected.  One 16550A clone is much like another.
> 
> I had lots of problems finding one that works via pci-e.
> 
> > > gpsd:INFO: KPPS cycle:  999928, duration:  779940 @
> > > 1372789172.778096721 gpsd:PROG: KPPS assert 1372789172.778096721,
> > > sequence: 4 - clear  1372789172.998064460, sequence: 5 gpsd:PROG:
> > > KPPS data: using clear gpsd:INFO: KPPS cycle:  999908, duration:
> > > 219967 @ 1372789172.998064460 gpsd:PROG: KPPS assert
> > [...]
> > 
> > That actually looks pretty good, most of the time.  Then it just
> > seems to miss some pulses.
> 
> Odd.
> Is that really fatal?

No, but it is the cause of the 10 second back off.

> Because minpoll is 4 only 1 in 16 seconds should matter, right?

Somewhat unrelated.  Minpoll is the gpsd->ntp interface.  We are
discussing the GPS/PPS-> gpsd interface.

But, yes, it does matter.  NTP is doing some pretty fanccy phase
locked loop things, having the sampling interval move around randomly 
affects that badly.

> > > What I don't understand: what does it need TIOCMIWAIT for? It
> > > already has the assert/clears?
> > Looks to me like it is missing a pulse now and then.  Can you
> > confirm your GPS is outputting true RS-232 levels?  That is plus
> > and minus 12 Volts.  Could also be a problem with interrupts on
> > your motherboard.
> 
> According to the manual it is TIA-232-F which according to wikipedia
> is true rs232.

Put a voltmeter or a scope on it.  I can count on one hand the number of
people I have met that have actually read that spec.  Unless it explicitly
says +/-12V you do not know.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
        address@hidden  Tel:+1(541)382-8588

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