Talking Raymarine / Autohelm Seatalk... any takers ?

captainslarty

captainslarty

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Hi all
I have quite a lot of info on the seatalk protocol and it looks straightforward, Datagram of up to 18 characters, 11 bits per char, 1 start, 8 data, 1 control and 1 stop, command no in C1, mandatory C2 and C3 for further instructions or data and optional 15 chars.
I am going to do some experimentation with PIC microprocessors over the winter, I have some ST decoding and encoding software already for the PC. Anyone with PIC Micro or similar experience want to "play" ?, let me know.. looks easy peasy to make remote controls, Joysticks, repeaters etc for a few quid each as a homebrew article. also looks entrirely possible to send custom datagrams over the seatalk bus for other uses, such as windlass control, heating, aircon, bilge monitoring and pumps etc..
Joe
 
Personally I am not at all enthusiastic about networking everything together. Concept is great and final result is very convenient -


Right up to the point when several gallons of salt water come crashing down the companionway hatch.
 
And what ?... /forums/images/graemlins/smile.gif
the netwok is protected, it is 3 cores, 12v Ground and data... waterproof connectors, I dont see the problem, apart from repeaters each instrument will work on its own without the network, simply a power supply.
Joe.
 
I have no PIC experience but I am very interested in what you are doing.
Soemone else trie to start a project like this a few years ago on one of the forums
 
Link to Seatalk info
Here is the link to Thomas´s site, he and a few others have done most of the hard work..
It really does look very easy peasy to do with a small micro, there isnt even the checksum as in nmea which is a pain to implement, straightforward but lots of code lines and calls.
I use Crownhill Picbasic compiler (Now proton, its the latest type with the dongle) and a bluebird development board, cant remember the programmer, its usb, used to use a serial epic programmer. Really great to use and great support, not cheap though. Nice thing is you can drop into microchip risc code at any time. I have the s2g course computer to fit with the new pilot and the Ray Joystick controller so can look at codes from this, the s2 includes a built in nmea to seatalk converter too and visa versa.
The more types of autohelm or st equipment that can be monitored the more a database of commands can be obtained.. purely as a hobby for personal experimentation of course............. you could never sell the units as st is a propriety protocol.
Also, there is plenty of space on the bus, the colision detection is so simple its great, we can add all sorts of other units. A small control plugs into the st bus for example, and at another point on the boat you plug into the bus with the rx, even a light switch lol...
Imagine one ST connection bidirectional to a PC and you could monitor every system in the boat that you hooked up, engine gauges would be easy, so would liquid levels etc...
Great fun, and useful too.. I can even convert my old Mariner instruments (Inside the saloon) to Seatalk, ST to PIC, PIC drives instrument. Any nmea instrument could be made ST comatible in its own right for about 2 quid and some fancy code..
Hope you find the link useful guys... it would be great to share ideas, why reinvent the wheel lol.. if anyones got some free web space we can publish the code and schematics for other builders.. if I ever get out of this Spanish hospital I can start playing inbetween refitting the boat /forums/images/graemlins/confused.gif /forums/images/graemlins/mad.gif
/forums/images/graemlins/smirk.gif
 
Hi Shaun,
Thomas is the driving force, I have looked at the small third party converters and they are actually pretty basic and limited in commands. there are some c code examples there for a c based microchip compiler, worth looking at but as said, the protocol is so simple. For general st nmea conversion its probably more cost effective to buy the ray st to nmea and rs232 converter, from the us its only around 70 squids.. however, as said a lot of the newer and older pilot computers have this built in,
its the ability to mod your own gear and make remotes and joystick or mini wheel steering, extra gauges and functions etc that I find most interesting. but loads of ideas will be forthcoming I am sure...
Joe.
 
Hello Shaun
That would be absolutely great. If we can just get a single page up with what we are planning and links to other seatalk sites such as thomas and the links he has, then it would be a start.. do you have any forum software, basic stuff, to add a small forum for sharing ideas ?...
Did you also notice the simple schematics for the bi directional st to pc converter ?, I have another one that is slightly better, will dig it out...
Are you into VB ?, I have quite a few years experience with VB but cannot think how to handle the control bit on TX (Basically the parity bit but not used as parity), on rx tis easy.... on a pic, its simple.. if someone can come up with a means of handling the bit using the vb serial routine then I will write a simple program to log in XP and send, there is an old one on Thomas´s site but too basic..
Havent got vb on this laptop so cant read up on the destructions at the mo.... there IS a link on T´s site to how someone did this but the link didnt work....
Will give it more thought though.
There are 255 possible commands by the looks of it (First character), so one single number could be all engine data, that gives a potential 255 engine related codes from 1 single command number in the first char.. if you use the apparantly unused 4 bits from Char 2 and 3 that gives over 4000 different ones..., at around 2-300 commands per second there is a lot of scope, a realistic limit of around 100 is probably ok on first appraisal...
There are also some nice uhf radio control modules available for around 40 squids, rx tx... this could be used with a remote control for some interesting results.... tack tick instruments anyone ??? /forums/images/graemlins/laugh.gif
Bit of solar panel, battery and tx.. there ya go...

Nurse !! ???? I need me steady pills....... /forums/images/graemlins/tongue.gif
 
Hi Joe
I too have been doing some work with S/T for a few "gadgets" I want to build. Knauf's work and collection of participant's work has been very helpful. The site put up by shaung should be very useful too, thanks Shaun. I look forward to being able to participate.
Ray
 
Excellent stuff Ray. What do you use, Pic ? or another embedded micro ?
I think we should be able to get a few basic units up n running in a month or so, as soon as time permits, I suggest, if you use a pic, developing the base io routine with timing, we may have to go interupt driven, select a suitable pic, the 18F series are great, loads of code space and io, loads of a to ds as well, pwm, hardware floating point units etc etc.. I am a year out of date on the newer pics, will do some research tomorrow. If we can get the io and timing correct on interupts with bus collision checking, then its a matter of building in a command look up routine and interpreter. thae command library could even be stored on an i2c prom and updated seperately. ?? if you dont use proton basic, then the hex and assembler code can be used as includes for you own assembler or your in ours etc. I already have all the button scan routines as incs and lcd drivers as incs, inc graphic lcds and text multiline ones. Nasa do a great unit, the clipper series navtex case that I have bought a few of, just the case buttons and display, about 40 quid I think, great graphics display. just needs a decent apx minus 10v for the contrast, I last used a pwm output to a voltage inverter and it worked on the bench and blew the crap out of it in the case.. doh !!!.. havent toughed it since... so if you have any ideas for a nice negative variable voltage inverter these are incredible graphics units and very pic friendly.
Look forward to getting the forum going..
Joe.
Anymore takers ? electronics gurus, pic programmers, case makers, waterproof button overlay makers or touch sensitive stuff, waterproof again, we can all share the results, if someone can design and build the cases then another of us could provide the electronics, maybe someone with access to pcb making machinery etc... someone who can supply waterproof connectors and sockets for the 3 wire bus.. anything that may help... industrial joystick supplier, on off and positional, small panel manufacturers, with lettering.. I am sure if we share skills the whole group inputting could share the fruits on a knock for knock basis.
Joe.
 
Building a custom PIC solution is a lot of work for just about anything. Why not simply pick up a cheap PDA? (unless it's the "fun" of trying to get a PIC system working that you are really interested in). Ready made fast hardware, easy to develop code for, built in display, built in interfaces etc...
 
The stuff I am doing (I have the ideas and do the research, but I contract out the code stuff) uses a PIC16F62X. It seems there is plenty of scope with that PIC to do whatever you may want. I found the SeaSigma utility to be very useful for testing and the SeaTalktest helpful for analysis but a little misleading until I really understood the way Raymarine use the Parity bit. I'll go into more detail in the forum if others are interested.
I am retired so messing with this S/T stuff is my version of doing the crosswords. Actually I hope a couple of my "gadgets" can become products to help cruisers. As to whether they can be really commercial is another matter.

I see that Raymarine have announced their ST70 series instruments which use "SeaTalkNG" (Next Generation). It is a backbone highspeed network which is probably a balanced line, but its topography using terminations and stub connections reminds me of the early co-ax ethernet systems. In any case, whatever we do playing with SeaTalk(1) is unlikley to give them any commercial grief, more like help them keep their "legacy" products working for the everyday boatie who does not want to replace their whole system.
BTW - what has taken you to hospital for your development work? Is it the only way you can get broadband?
Ray
 
Muckypup, I fully agree with Gypsy, its like doing crosswords, great fun for me. I dont find making a custom pic solution hard work at all. Compared to the nmea solutions I have done this one is easy. I use a superb compiler for 95 % of the code, and PIC risc code for the rest. Once a library of routines are built up it is even simpler... no worries at all. The PDA will not provide stand alone functionality and I dont see it as an option for what I want. I have PICs linked to embedded gps modules already here that may be fun to integrate.

Anyways Gypsy. Re the hospital, check the liveaboard forum.... its a continuation of my tour of european hospitals by boat...
The new protocol that RM use (Seatalk 2) - not sure if this is the same as NG, is, I believe CANBUS based, I dont see the need myself but many firms (Lowrance for example, are pushing NMEA 2000 which I also believe is CAN based. I have the plug ins for the compiler and its a bit of a bitch... I think ST1 and NMEA 0183 will be with us for a long time.
I would be VERY interested in info on the command bit and any other specifics, please mail me or PM me, or indeed when Shauns forum is fully running please contribute.
I too am retired, retired at 47... full time liveaboard and loads of time to play, it is my real hobby (Electronics, especially Micro) , apart from the boat duties lol.
Microchip are also integrating more and more CAN modules into some of the later PIC micros, and the compiler and development environment I use for PIC is being updated all the time, so no doubt in the future the ability to link NMEA2000, ST2 and the existing protocols will be no problem, but as I dont intend changing the equipment on the boat, no worries for me.
Thanks for input Gypsy,
Joe.
 
[ QUOTE ]
There is now a link to forum on http://www.total-safe.co.uk/seatalk

[/ QUOTE ]

I know - this thread is quite old .....
Are you still here - and what happend to the link above ?
It's not working anymore. Is it just temporarily offline or has it moved to to a new place ?
I'm also doing ST-stuff - Listener and Talker and Repeater Display and Alarms etc. I Would like to get in touch with other's who are also making electronics and software for St.
Maybe you could have a look at the forum at gadgetPool.de or reply here.


Thanks
Frank
 
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