NMEA to SEATALK1

[Sven Fredriksson]

Is there anybody who can tell how to build a NMEA0183 to SEATALK1 converter.
A complete solution, both hard- and software would be appreciated.
Maybe possible to modify the here mentioned SEATALK1. to NMEA0183 converter.
Most desired is a NMEA2000 to SEATALK1 converter
but a NMEA0183 to SEATALK1 would do.
The signals needed to be handled are:
NMEA0183/NMEA2000     SEATALK1    Description
MWV        /130306          10                         Wind angle
MWV        /130306          11                          Wind speed

Unfortunately my Raspberry Pi experience is none.
However, I have some old knowledge in both hardware and software.
 
The situation is as follows: Have an old Raymarine Autohelm ST2000 tiller autopilot only accepting SEATALK1 input signals. Can’t find any affordable converter on the market.
The boat is equipped with a mast top wind transducer transmitting NMEA0183.
A speed instrument transmitting SEATALK1
A multiplexer converting and mixing all in to a NMEA2000 buss.
A plotter connected to the NMEA2000 buss.

Would be very grateful for help.


Would be very

[abarrow]

The main reference for both hardware and the SeaTalk codes, is here: http://www.thomasknauf.de/seatalk.htm.

There are a lot of NMEA0183 <- SeaTalk converters out there, but not as many that convert both ways (they do exist).

There is Seatalk input capability in a SignalK plugin, but again, it is from Seatalk in to SignalK, and not the other way. It is do-able, it's just a case of someone taking the time to write the code.

[Techstyle]

Based on what you have it looks like you only need to receive the Seatalk 1 and then broadcast it out to other devices if so:

Seatalk 1
Hardware
Using the hardware below:
https://www.amazon.com/dp/B07YJL3MQQ

First, remove the resistor on the input side and replace with a 10K

Then connect the Seatalk Data (yellow) wire to the input + and the Seatalk Ground (black) wire to the Input -
On the opposite side connect 3.3V and ground from the Pi to VCC and GND respectively and connect the Output to a previously unused GPIO pin - for example Pin 7, which is GPIO 4.

GPIO App
Go into settings (--> Openplotter -->Settings) and ensure that the GPIO App is installed and the latest

In the GPIO App, go to the Seatalk 1 tab and click on "Add SK Connection". In the dialog box add the required information and then press the "Enable Seatalk 1 reception" button. Pick the GPIO pin you are using (I was originally using GPIO 25 and later changed to GPIO 4 as the CAN Hat uses 25)

then you will need a USB to RS422 device for bi-directional NMEA0183 connections - follow this guide:
https://openplotter.readthedocs.io/en/la...mples.html

and for the NMEA2000, follow this guide:
https://openplotter.readthedocs.io/en/la...n_app.html
there may be a better piece of hardware because the one in the guide isn't isolated (although I have used it without issue) - https://www.waveshare.com/2-ch-can-hat.htm <-- I have not tested this one