------------------------------
Message: 2
Date: Tue, 1 Dec 2020 13:52:23 -0800
From: "Gary E. Miller" <gem@rellim.com>
To: <gpsd-users@nongnu.org>
Subject: Re: NMEA but no PPS in ntp, Ubuntu 18.04.5
Message-ID: <20201201135223.361f4bb7@spidey.rellim.com>
Content-Type: text/plain; charset="utf-8"
Yo Steve!
On Tue, 1 Dec 2020 15:24:18 -0600
Steve Bourland <sbourland@swri.org> wrote:
Super happy to learn about new places to look for information :)
So much internet, so little time.
> But no PPS. You also do not have enough other chimers. Hard to
> vote with only 2 voters.
I have 4 other voters but figured their info wasn't relevant, and
knew I was already going to have a long message, just trying to keep
it as short as possible.
When removing data, this tells us you did: [...]
> That is good. What is your gpsd command line? See it this way:
> # pstree -paul | fgrep gpsd
# pstree -paul | fgrep gpsd
|-gpsd,25099,nobody -b -n /dev/ttyS0
| `-{gpsd},25100
| |-grep,25730 -F --color=auto gpsd
Why are you using -b? That is to fix Bluetooth problems. Otherwise looks
good.
> Uh, you have if backwards. The kernel feeds PPS to gpsd. Then gpsd
> uses a SHM to eed it to ntpd.
Is the lack of /dev/pps0 on the gpsd command line causing the issue?
Normally not. But cant hurt to try it. Then your PPS would be
on SHM(2) if you did: gpsd -n /dev/ttyS0 /dev/pps0
What does this show:
gpsd -n -D 6 /dev/ttyS0 |& fgrep PPS
It should show PPS being configured properly. As long as you start as root.
ntpshmmon
ntpshmmon: version 3.21
# Name Seen@ Clock Real L Prc
sample NTP0 1606854237.160599667 1606854236.723461751
1606854236.000000000 0 -20
sample NTP2 1606854237.160618091 1605548548.531056191
1605548548.000000000 0 -20
For some reason your PPS is on SHM(2), not SHM(1). Odd, that usually
happens when you ut /dev/pps0 on the gpsd command line.
Adjust your nto.conf to fit and it should all work fine.
Using this super cool new tool on a functioning system,
I see NTP2, NTP3, and then NTP0, NTP1 every second.
That would mean you have two serial and two PPS sources nn that system.
> You need to be running gpsd and ntpd as root, of course.
They both start as root but then drop privleges so gpsd runs as
nobody, and ntpd runs as "ntp." I believe this is expected behavior?
Yes. Good.
So hopefully I'm following along here, but it looks to me like gpsd
isn't putting the PPS timing in the shared memory for ntpd,
No. We confirmed gpsd is putting PPS on SHM(2), not SHM(1) as you,
and I, expected.
Restarted gpsd on the command line with -D 5 to see if there was
useful information:
Once again, the interesting parts you deleted. Do this:
# gpsd -n -D 6 /dev/ttyS0 |& fgrep PPS
RGDS
GARY
temp.txt