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Re: [gpsd-dev] Problem with PPS detection - using Centos 7 and gpsd dev-

From: Gary E. Miller
Subject: Re: [gpsd-dev] Problem with PPS detection - using Centos 7 and gpsd dev-3.19a
Date: Mon, 14 Jan 2019 10:13:59 -0800

Yo Mick!

On Mon, 14 Jan 2019 13:27:20 +0000 (UTC)
Mick Durkin <address@hidden> wrote:

> 1) The Perle driver.
> I could attach this, but it is a largish source RPM, so it may be
> better if you access it directly from Perle's website.

Since you proved below that the problem is in the Perle driver I
don't need to look at the source for confirmation.  Complain to them.

> 2) Compile gpsd without kpps.
> This took a bit of doing, but eventually I was able to make it
> compile by

All you need to do was remove /usr/include/sys/timepps.h

> it ran
> nicely and detected my PPS via the "ioctl (TIOCMIWAIT)" path.

Yup, that proves it, your Perle driver does not support PPS.  The
TIOCMIWAIT times will be almost as good as the KPPS times, so you
can start there while waiting for Perle.

> I included the messages from "NTP:" this time as
> it shows timevalues with -20 and -30 precision, so it looks like gpsd
> is shipping both sets of data to ntp.

The 'precision' is a made up number.  It is not telling you anything
useful.  Use ntpmon and ntpviz to see how well your PPS is working.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin

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