OpenCPN GPS RPi

[PlanC]

Setting up OpenCPN using a GPS HAT L76X on RaspberryPi4. GPS indicator on the RH top corner of the OpenCPN page shows red so not receiving the GPS signal. Any help please?

[barcoMeCasa]

are you using the openplotter image?

[PlanC]

Yes, OpenPlotter.

The OpenCPN and Signal K are running but something is not connecting.

[barcoMeCasa]

out of the box Opencpn should be listening to signalk on port 10110 so if the gps data is getting into signalk it *should* go straight through to opencpn.
Here's my GPS in signalk >


But its usually easier to let openplotter set it up for you, in the serial app >>

https://openplotter.readthedocs.io/e...erial_app.html

If all's well it GPS data should show up in the signalk databrowser >>



Any of that sound familiar?

[PlanC]

yes it was set up in the OpenPlotter serial app and appears to be correct. There is a Check System which shows OpenCPN and SignalK running. But OpenCPN shows red not receiving. I will check again. Thanks.

[barcoMeCasa]

Originally Posted by PlanC

yes it was set up in the OpenPlotter serial app and appears to be correct. There is a Check System which shows OpenCPN and SignalK running. But OpenCPN shows red not receiving. I will check again. Thanks.

If signalk saw it & set it up it *should* be OK..... 🤔🙂

Another thing you can check is a bit more techy..

Do you ever use the terminal? It's in the accessories menu >



Then (with apologies if you know this already..) you can type in "ls /dev" & see what's there. Very quick overview - ls means list, so ls /home/pi will list all the files & folders in your home folder (also known as a directory)

Mine looks like this >

pi@openplotter:~ $ pwd
/home/pi
pi@openplotter:~ $ ls
backup        Desktop    lnkToMusic         Music     rpdiags.txt   Videos
bash_scripts  Documents  log.txt            Pictures  RTIMULib.ini
charts        Downloads  misc_audio_alerts  Public    Templates
pi@openplotter:~ $ ^C
pi@openplotter:~ $

pwd is print working directory, just shows you where you are.

So what you can do now is "ls /dev"
The "dev" directory is where the hardware lives, should look something like..


Looks bit daunting but not really that bad, the files of interest here are

ttyOP_compass  
ttyOP_gps      
ttyOP_wind
ttyUSB0            
ttyUSB1       
ttyUSB2

So I have 3 usb/serial inputs - if you have only the gps attached then probably just see something like ttyOP_gps (this is just a shortcut openplotter creates to make things a bit easier for the pi) and probably /dev/ttyACM0

Nearly there, now you can type "cat ttyOP_gps", can''t remember what "cat" stands for but it lists anything coming out of ttyOP_gps so on mine...

pi@openplotter:~ $ cat  /dev/ttyOP_gps
$GPRMC,145853.00,A,2745.58990,N,01541.13500,W,0.091,,240124,,,A*6A
$GPVTG,,T,,M,0.091,N,0.168,K,A*24
$GPGGA,145853.00,2745.58990,N,01541.13500,W,1,08,1.03,6.5,M,35.5,M,,*45
$GPGSA,A,3,28,32,16,29,31,26,18,25,,,,,2.07,1.03,1.79*05
$GPGSV,3,1,10,12,03,075,,16,09,276,33,18,32,144,34,25,31,061,37*7D
$GPGSV,3,2,10,26,30,298,35,27,02,225,,28,71,339,41,29,58,037,43*7C
$GPGSV,3,3,10,31,45,324,46,32,35,210,41*7D
$GPGLL,2745.58990,N,01541.13500,W,145853.00,A,A*7A
$GPRMC,145854.00,A,2745.58988,N,01541.13495,W,0.177,,240124,,,A*60
$GPVTG,,T,,M,0.177,N,0.328,K,A*2B
$GPGGA,145854.00,2745.58988,N,01541.13495,W,1,08,1.03,6.4,M,35.5,M,,*47
$GPGSA,A,3,28,32,16,29,31,26,18,25,,,,,2.07,1.03,1.79*05
$GPGSV,3,1,10,12,03,075,,16,09,276,29,18,32,144,35,25,31,061,39*79
$GPGSV,3,2,10,26,30,298,30,27,02,225,,28,71,339,40,29,58,037,41*7A
$GPGSV,3,3,10,31,45,324,44,32,35,210,34*7D
$GPGLL,2745.58988,N,01541.13495,W,145854.00,A,A*79

all's well here, lots of nmea coming in.
You should see the same, if not then we know a bit better where to look.

Leave that with you for now

[cas206]

cat stands for concatenate. cat file1 file2 ... copies the contents of file 1 to standard output (the screen) and then file2, etc. cat file1 file2 ... > file_out would redirect the concatenated files into the file_out file. But probably the most common usage is cat file1 which just copies the single file contents to the screen.

[rgleason]

In Windows if you already have an application using the GPS, it is a serial port and is not released to provide services to another application looking for it. Don't know if linux is the same.

[barcoMeCasa]

Originally Posted by rgleason

In Windows if you already have an application using the GPS, it is a serial port and is not released to provide services to another application looking for it. Don't know if linux is the same.

Seems unlikely in this case, openplotter does a very good job at setting things up if you follow the documentation.

[rgleason]

Then reboot it.

[cas206]

The Waveshare GPS HAT L76X page had instructions for installing drivers. (https://www.waveshare.com/wiki/L76X_GPS_HAT). I don't know if OpenPlotter already has them installed. You might have to ask them about it unless someone here already has experience with that hardware.