Seatalk to NMEA 0183

[GeorgeSmith]

Looking for a way to get my Seatalk data into Open CPN as NMEA 0183 data.
I can do the transistor hardware stuff but need a program to run in a Arduino UNO to do the software. Or any other suggestions to get the job done without breaking the bank?
Basically: Seatalk to NMEA 0183 converter.
Thanks
George

[nohal]

George...
Then use the Arduino part of Freeboard [MeshCMS]

Pavel

[Lake-Effect]

Some info here.

This person has put together a Seatalk interface using a PIC (my microcontroller of choice) that connects right to USB. Cool.

[GeorgeSmith]

Thanks. I'll look at it again. Didn't know you could just use that part of it.
Do you think I can use the UNO or do I need the larger Arduino?
George

[nohal]

George...
How good are you at programming for AVR microcontrollers? If not at all, then sure not with Freeboard.
From the names of the repositories at https://github.com/rob42?tab=repositories it is obvious which ones are supported (read the respective README documents, the Due has limitations you will probably not like)

Pavel

[JONA]

Originally Posted by Lake-Effect

Some info here.

This person has put together a Seatalk interface using a PIC (my microcontroller of choice) that connects right to USB. Cool.

Hi,

You can find an implementation of Thomas Knauf interface on the 3.3 version on

https://github.com/JONA-GA/OpenCPN/tree/devga.

ST/nmea converter is in software and included in Opencpn.
Currently working in Linux and read only.

Gilles

[muttnik]

Originally Posted by JONA

Hi,

You can find an implementation of Thomas Knauf interface on the 3.3 version on

https://github.com/JONA-GA/OpenCPN/tree/devga.

ST/nmea converter is in software and included in Opencpn.
Currently working in Linux and read only.

Very interesting. I'm trying to get my head round the logic you're using for detecting the command bit: Can you explain it? I'm not sure I understand how this can be done using parity error detection with odd parity set.

[muttnik]

Originally Posted by muttnik

I'm not sure I understand how this can be done using parity error detection with odd parity set.

OK I see it now: Very good! When I implemented something similar I was using space parity (parity error indicates cmd byte). Your version has a marginal overhead in the additional parity calculation but is superior in being more widely usable: space parity not being POSIX (no mention in the MacOS terms man page) and not all Linux serial to usb drivers supporting it (I had a keyspan one which didn't).

Minor thing to note for users: Not all serial to usb devices implement parity error checking correctly (even straight forward odd parity). I was testing a startech one last year which gave a parity error on the byte *after* the one which actually had the error. Startech eventually acknowledged the bug and were supposed to be sending me a new device when they'd fixed it but I never heard form them again....

[sy_gilana]

+1 on the Yapp electronics one, and there are others that are multiplexers too.

The benefit here is that the output is USB in NMEA 0183 format.

www.gadgetpool.de - Die Homepage

and

YAPP Electronics - Home Page for YBW

Why re-invent the wheel?

[JONA]

the "gadgetpool.de " is ok ( and isolated!) for the hardware interface.
The "idea" is to realize the Stk-nmea converter in software and include it in Opencpn.
As the Stk is using a 9bit serial, classically it is possible to read it on an UART at 8bit and using the parity bit. On my implementation, I use a particularity of POSIX driver in LINUX ,wich leave intact the data with parity error and include two special characters before the data with "faulty" parity. Unfortunatly,this behaviour is not present in the windows driver ( The "faulty" data is zeroed !!...).
As far as I know, it's necessary to write a "special" serial device driver for Windows (not so easy task...).
It's possible that this solution should work with MacOs, but I can't test it.
I will test it on Prolific driver ( serial to usb) asap.
@Muttnik thanks for your comments

Gilles

[scruzin]

If you're comfortable coding, there's quite a bit out there on Arduino forums for interfacing Seatalk. The trick is to the use 9-bit version of Arduino's Hardware Serial. Bit 0x100 is set to 1 for the first byte of the Seatalk message, then 0 thereafter.

Just search for "Seatalk using Arduino."

[RhythmDoctor]

vYacht Yacht automation