Raspberry Pi 4 and OpenCPN

[brice3010]

Hopefully this,is the right place for this question.


After every restart on my Raspberry Pi 4 I have to reinitialize the USB GPS module for OpenCPN to recognize it.


Following commands are needed, ref.: https://www.zwiebelfam.nl/een-gps-tr...-de-raspberry/


pi@raspberrypi ~ $ sudo systemctl stop gpsd.socket
pi@raspberrypi ~ $ sudo systemctl disable gpsd.socket

These are needed to free the listening to USB port listening

And this one to let gpsd know that a GPS device is available on a USB port:


pi@raspberrypi:~$ sudo gpsd /dev/ttyUSB0 -F /var/run/gpsd.sock

My question is how to include these commands in a service so that at startup these are executed automatically.

[scargo]

Originally Posted by brice3010

Hopefully this,is the right place for this question.


After every restart on my Raspberry Pi 4 I have to reinitialize the USB GPS module for OpenCPN to recognize it.


Following commands are needed, ref.: https://www.zwiebelfam.nl/een-gps-tr...-de-raspberry/


pi@raspberrypi ~ $ sudo systemctl stop gpsd.socket
pi@raspberrypi ~ $ sudo systemctl disable gpsd.socket

These are needed to free the listening to USB port listening

And this one to let gpsd know that a GPS device is available on a USB port:


pi@raspberrypi:~$ sudo gpsd /dev/ttyUSB0 -F /var/run/gpsd.sock

My question is how to include these commands in a service so that at startup these are executed automatically.

I am going to guess. As I have no experience with gpsd. But I have been a UNIX sysadmin for more than 25 years or so. I know, Linux (with systemd) is different.


if -F fixes you issues, and according to the man page it creates a control socket for device addition and removal commands, than my recommandation to you is

1. if you have a config file, you can add it there to GPSD_OPTIONS variable, and at startup, the system will execute it.
2. or if you are not sure, you can edit your systemd service file (should be somewhere like /usr/lib/systemd/system/gpsd.service) and add it to the variable ExecStart
   something like:
   ExecStart=/usr/sbin/gpsd $GPSD_OPTIONS /dev/ttyUSB0 -F /var/run/gpsd.sock

BTW, when you disable a service, it will not start the next time your start or restart your system. It will remain disabled until you explicitly enable it and start it (or restart your system after enabling it)



Good luck

[seandepagnier]

gpsd is.... well...


You should probably not pass the serial port to gpsd especially if using a control socket


Instead just use gpsdctl add /dev/ttyUSB0


It's recommended to write udev rules to do this for you and it can add and remove the gpsd device automatically at boot as well as while running. This basically solves the issues from what I can tell.

[brice3010]

Thank you very much for your replies scargo and seandepagnier. Reading your replies I realise that a bit more context would be useful.


Following contents is present:


/lib/systemd/system/gpsd.service shows:


[Unit]
Description=GPS (Global Positioning System) Daemon
Requires=gpsd.socket
After=chronyd.service


[Service]
Type=forking
EnvironmentalFile=-/etc/default/gpsd
ExecStart=/usr/sbin/gpsd $GPSD_OPTIONS $DEVICES


[Install]
WantedBy=multi-user.target
Also=gpsd.socket




Also: /usr/sbin/gpsd when opened in nano contains a lot of "garbage" and "is not writeable".


/etc/default/gpsd contains:


START_DAEMON="true"
USBAUTO="true"
DEVICES="dev/ttyACM0"
GPSD_OPTIONS="-n -b"
GPSD_SOCKET="/var/run/gpsd.sock"


I left the comments out from the contents above.


Somehow, using ttyACM0 works to get the GPS signals in my system; ttyUSB0 is not used (I think).


Now from the above, would you coroborate that your replies are still valid?

[brice3010]

Reading this post https://www.raspberrypi.org/forums/v...c.php?t=138711 I opened /lib/systemd/system/gpsd.socket and found this:


[Unit]
Description=GPS (Global Positioning System) Daemon Sockets


[Socket]


ListenStream=/var/run/gpsd.sock
ListenStream=[::1]:2947
ListenStream=0.0.0.1:2947
SockeMode=0600


[Install]
WantedBy=sockets.target




Surprised by the address 0.0.0.1:2947 I changed that to 0.0.0.0:2947


After hard reboot the GPS was read properly by OpenCPN. Not quite sure how this wrong localhost address could have been programmed... ?