OpenCPN as repeater/aggregator with virtual COM ports

[ian5142]

Hello All,
I currently run OpenCPN on a Toughbook which has only one accessible USB port. I am in the process of using a rPi 4 as a NEMA aggregator. It receives data from the sounder, GPS, AIS, and an Arduino heading sensor.

The GPS data is modified slightly (time & date) by my own Java program running on the Pi. https://github.com/ian5142/nema0183_aggregator/
(ignore the Readme, I haven't updated it). The program outputs the updated serial data on a virtual COM port. In this case I have it hard coded to /dev/ttyS20. On boot the rPi has the following to create a COM port bridge:
/usr/bin/socat pty,raw,echo=0,link=/dev/ttyS20 pty,raw,echo=0,link=/dev/ttyS21 &

In OpenCPN on the rPi, I have configured all of the inputs and the single output (115200 baud). The only problem is that the GPS modified input does not show up in the OpenCPN port dropdown list or work when I type it in manually. Baud rate is correct. I know my Java program works correctly because I can see the output of it using screen (on /dev/ttyS21).

Any ideas?

[nohal]

Use UDP or TCP between your Java program and OpenCPN (And between the RPi and the Toughbook) and save yourself the endless headache with serial ports.
Especially if all you need the RPi for is the multiplexer, there are probably better options than OpenCPN, like kplex or SignalK server.

[bcn]

OpenPlotter does run not only on RasPis but as well on other Linux distros. With kplex and SK installed. Plus a user community to support that part.
OCPN is the plotter of course...

[ian5142]

The toughbook only has an accessible USB port, no ethernet. Just the difficult place it is mounted. I am not using wifi for this, not reliable enough. My java program is setup to output on a virtual serial port, created using socat. That part works fine.


I started to setup kplex today. I still want to output via serial, actually UART from the Pi, to UART-USB device on the toughbook. I can't get kplex to output anything yet though.
The output serial section on the kplex config file is:
[serial]
file=ttyAMA3
baud=115200
direction=out

name=output


Above it are all of the serial inputs. I have abandoned the OpenCPN on the Pi idea.

Anything I am missing?


PS: Anyone know how to have an arduino connected via USB output serial on boot, plugged into the Pi. Every time I reboot the Pi, I have to go and click the reset button the Arduino in order for it to output serial data to the Pi. This won't work when it is all mounted.

[nohal]

I would probably still prefer USB-to-Ethernet over USB-to-UART.

I am also from personal experience not exactly convinced wi-fi is any less reliable than a cascade of physical, virtual and media converted serial ports at distances found on an average boat.

You can reset the Arduino from the RPi whenever you need via its reset pin connected to one of the GPIO pins on the Pi (See for example https://electronics.stackexchange.co...-a-atmega3285v if by Arduino you mean some of the 5V ones) or perhaps you can make the Arduino reset itself when it detects the communication with the Pi is not working.

[ian5142]

I have got Kplex and my java program working on the Pi. Now the only problem left is why the Arduino won't output serial until the board is reset either by pressing the button or uploading new code to it. It is recognized by the Pi before then though. Just no serial output.