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Re: [gpsd-users] GPSD SOCK output without PPS

From: Zach LaCelle
Subject: Re: [gpsd-users] GPSD SOCK output without PPS
Date: Wed, 12 Sep 2018 16:28:30 -0400

Hi Gary,

Per my parallel thread, the environment is Ubuntu 16.04, kernel 4.15.0-34-generic, gpsd 3.15-2build1 from the PPA.

I don't have PPS because I'm using the USB connection to the EVK-7P initially (I will eventually wire it in, but haven't yet). So I don't believe the PPS is supported through this connection. Indeed, when I connect this way I get the following:

"KPPS:/dev/ublox kernel PPS unavailable, PPS accuracy will suffer"

The kernel module is definitely there:
$ lsmod | grep pps
pps_core               20480  1 ptp

Like you pointed out, SOCK doesn't give me any value over SHM for now. It will once I have PPS working, and I was hoping to have the environment already configured by that point. No big deal, just wanted to see if I had the configuration working. I'll give your command for looking at socket traffic a try once I can go outside with the GPS again.



On Wed, Sep 12, 2018 at 3:52 PM Gary E. Miller <address@hidden> wrote:
Yo Zach!

On Wed, 12 Sep 2018 11:00:48 -0400
Zach LaCelle <address@hidden> wrote:

> I'm testing out a u-blox EVK-7P, and would like to get the
> gpsd->chrony pipeline working well on the bench before building out
> the system. I have the SHM interface working for normal, rough
> synchronization, but I'd eventually like to wire in and use the PPS
> output.

Sounds like you are almost there with SHM.

> I understand that the PPS source won't work until I do, but I was
> hoping to test out the SOCK interaction, even without the PPS
> accuracy wired in.

SOCK should work fine without PPS.  But is SHM is working, what value
does SOCK give you?

> However, I don't receive any messages over the
> socket connection.

How do you know that?

> I used strace to look for send.* = (32|40)$ messages out of GPSD, and
> I don't see any. But, when I run it with debugging flags, I do see a
> line saying "PPS:/dev/ublox using chrony
> socket: /var/run/chrony.ublox.sock"

Much easier ways to sew what is happening.  Try this:

gpsd -nND 6 /dev/ttyUSB0 |& fgrep socket

> Is this something I can use without PPS wired in?

Yes.  But why do you not have PPS?

Also, you left out key details.  What gpsd version are you using?
How was it built?  How are you starting gpsd?  Hwat is your GPS?

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

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    "If you can’t measure it, you can’t improve it." - Lord Kelvin

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