Re: Only one client at a time (Debian, Raspbian)

[Carles Pina i Estany]

Hi,

On Jul/29/2021, Gary E. Miller wrote:

Thanks for all your work on gpsd! .-)

> Yo Carles!

Hi Gary!

Thanks for your answer - I'm new with gpsd - if I do "strange things"
making my life difficult please let me know, I might not have discovered
the easy way!

> On Wed, 28 Jul 2021 22:19:24 +0200
> Carles Pina i Estany <carles@pina.cat> wrote:
> 
> > I have a Garmin eTrex 30x GPS connected using USB to either my
> > computer (Debian Buster) or to a Raspberry pi (Buster as well).
> 
> I'm curious how you got any NMEA out of the eTrex.  Many people
> report failure at that.

I have now:
pi@raspberrypi:~ $ lsb_release -a
No LSB modules are available.
Distributor ID: Raspbian
Description:    Raspbian GNU/Linux 10 (buster)
Release:        10
Codename:       buster

pi@raspberrypi:~ $ gpsd -V
gpsd: 3.20 (revision 3.20)

# (this gpsd is from buster-backports)

pi@raspberrypi:~ $ cat /etc/default/gpsd
# Devices gpsd should collect to at boot time.
# They need to be read/writeable, either by user gpsd or the group dialout.
DEVICES=""

# Other options you want to pass to gpsd
GPSD_OPTIONS=""

# Automatically hot add/remove USB GPS devices via gpsdctl
USBAUTO="true"

START_DAEMON="true"

Then I connect the eTrex, I answer "No" for the "USB Mass Storage".

In the Pi things like cgps or gpsmon work fine.

Then I use kplex with this setup:
pi@raspberrypi:~ $ cat .kplex.conf
[tcp]
gpsd=yes
direction=in
mode=client
address=localhost
persist=yes
retry=10

[tcp]
direction=out
mode=server
port=10110

[file]
filename=/home/pi/gps.txt
direction=out
append=yes

And I get the NMEA strings doing "telnet 192.168.1.4 10110" (or
localhost...) and in the file.

Quick question if you don't mind: off the top of your head: do you
expect "Garmin GLO 2" device to work? I think that it's this one:
https://buy.garmin.com/es-ES/ES/p/645104#overview

I'm new in all this world and I don't know how often things "just work"
(like a USB memory stick, in a standard way) or if they are very
specific to each device.

> > I installed "gpsd" Debian package and then I'm trying to have two
> > different software access the gpsd over the port TCP 2947:
> 
> I can't speak to the Debian package,  that is not from us.

I updated gpsd Debian package to a newer version solved the problem that
I had (but I might have new problems! - after 10 or 20 min it seems to
sometimes just stop. I haven't done more testing yet).

> 
> > -kplex for reading it and saving into files / send NMEA string over
> > the network
> 
> New one on me.  Why use it?

Ideally I would like gpsd to get the positions from the eTrex 30x
(whatever the on-wire protocol between gpsd and eTrex use) and then I
would like gpsd to:
-Save NMEAs to a file
-Make NMEAs available over a TCP port

My understanding is that gpsd cannot do this. If it can let me know
please. kplex is a gpsd client as well (recently, last time that I had
used in 2017 didn't have this capability) and can save into a file and
make it available over a TCP port (pushing the NMEA strings).

How could I do it without kplex?

> > -qgis (which doesn't have TCP NMEA alike but gpsd)
> 
> I do not understand that last bit: "(which doesn't have TCP NMEA alike
> but gpsd)"

qgis has a gpsd client (as, it can connect to the port 2947 and
communicate using the gpsd protocol like:
?WATCH={"enable":true,"json":true} and alike).

As far as I know qgis cannot connect to a port and read NMEA strings
like OpenCPN can do (or like I do with "telnet IP PORT" and I just get
it from kplex).

OpenCPN has both: connect and read NMEA strings or do the gpsd client
version. I was just discussing my setup in case that it was relevant.

> > I realise that gpsd 2947 port in Debian/Raspbian is handled by systemd
> > socket activation (which I've never used before... so I might be
> > missing something).
> 
> I also do not use systemd(umb), but I know it causes daily complaints
> on this email list.

For what I saw yesterday: I'm not surprised, I found it confusing how
things work, auto-activate, systemd socket activation to the port, etc.

> > As soon as one software (e.g. kplex) uses it, the other one (qgis)
> > cannot use it.
> 
> I often connect multiple clients over port 2947 with no problem.  For
> example: xgps, xgps and gpspipe all at the same time.
> 
> Can you connect two cgps?  Or one cgps and one xgps?

I could connect two cgps after upgrading gpsd to a newer version than
what I had in Debian Buster (3.17 to 3.20)

> > If I do it using telnet:
> > 
> > Terminal 1:
> > pi@raspberrypi:~ $ telnet localhost 2947
> > Trying ::1...
> > Connected to localhost.
> > Escape character is '^]'.
> > {"class":"VERSION","release":"3.17","rev":"3.17","proto_major":3,"proto_minor":12}
> 
> 3.17 is ancient.  3.23 is to be releassed bext week.

with 3.20 it works fine... (different clients) for a while! After a
while (10, 20 min) it stops working and I need to disconnect and connect
the GPS. Still using systemd.

> 
> > I've been trying to not have systemd and use just gpsd but I had other
> > problems - that I can show step by step but hopefully not needed. I'm
> > happy to fix what I have not to replace everything.
> 
> Remove gpsd fro systemd(rool), then just start gpsd normally, as root:
>         gpsd -n /dev/ttyXX

will do when I have problems.


-- 
Carles Pina i Estany
https://carles.pina.cat