A deadly dull YAPP

AngusMcDoon

AngusMcDoon

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This one is just dull. Nothing flashy or novel about it at all, but I have had a few requests for it, so here goes. It's a Seatalk (old style) to NMEA-0183 bi-directional bridge. Stuff coming in on the Seatalk side gets translated and spat out the NMEA-0183 side, and vice-versa. As Seatalk is bi-directional and everything links together there's only one Seatalk connection for in and out. For NMEA-0183 there's an in line and an out line. The out line also has a RS-422 like output and a RS-232 output to cover all hardware variants of NMEA-0183. The NMEA-0183 input handles either type and is opto-isolated (which means if you accidentally connect your shore power main voltage or something similarly daft to the device input it won't destroy all your instruments, just expire with a fizz and a burp itself). The device is powered from Seatalk and takes 42mA at 12V. I might try to get that reduced in software.

This is only a limited version as the processor is small in size and I can't fit any more functionality in. These message types are handled in both directions...

Depth
Boat speed
Heading true and magnetic
Magnetic variation
Wind speed and direction, true and apparent
Temperature
Latitude and longitude
Course over ground
Speed over ground
Time and date
Trip and total log
Rudder angle

and these are the NMEA-0183 messages handled...

DPT, DBT, VHW, RSA, HDM, HDG, HDT, MTW, VLW, VWR, VWT, MWV, RMC, GLL

Any message type can have its output rate configured or switched on or off by hooking up to a serial terminal and using a simple text line interface. A wacky cable is needed to do that but is easy to make with parts from Maplin, or else everything can be left at the defaults which are sensible values.

What's missing in this limited version are autopilot and route type stuff as found in RMB, XTE and APB messages. If anyone needs those messages I would recommend Frank Wallenwein's device which has more functionality here...

http://www.gadgetpool.de/bestellen/catalog/product_info.php/products_id/29/language/en

I could go to a bigger processor but it would mean an ARM or suchlike as I am at the limit of PICness. That would bump up the price, and as Frank has already done it, I'll leave the higher functionality stuff to him.

Here's a pic of the board...

sdc12357.jpg


and here it is in its box...

sdc12359.jpg


It's all open source as usual. Source, schematics and layout are all here...

http://yappelectronics.co.uk/STN.htm

I haven't written a manual yet. If anyone would like one in any state of build or even just advice on how to do it yourself let me know.

For the complainers - the mods have sanctioned YAPPs in a low-numbers non-profit-making way if they are open source, which they are.
For those worried about CE marking - these devices are not CE marked but I have a dispensation from Trading Standards to share these hobby projects, again in an open source non-profit-making low-numbers way.
 
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AngusMcDoon said:
This one is just dull. Nothing flashy or novel about it at all, but I have had a few requests for it, so here goes. It's a Seatalk (old style) to NMEA-0183 bi-directional bridge. Stuff coming in on the Seatalk side gets translated and spat out the NMEA-0183 side, and vice-versa. As Seatalk is bi-directional and everything links together there's only one Seatalk connection for in and out. For NMEA-0183 there's an in line and an out line. The out line also has a RS-422 like output and a RS-232 output to cover all hardware variants of NMEA-0183. The NMEA-0183 input handles either type and is opto-isolated (which means if you accidentally connect your shore power main voltage or something similarly daft to the device input it won't destroy all your instruments, just expire with a fizz and a burp itself). The device is powered from Seatalk and takes 42mA at 12V. I might try to get that reduced in software.

This is only a limited version as the processor is small in size and I can't fit any more functionality in. These message types are handled in both directions...

Depth
Boat speed
Heading true and magnetic
Magnetic variation
Wind speed and direction, true and apparent
Temperature
Latitude and longitude
Course over ground
Speed over ground
Time and date
Trip and total log
Rudder angle

and these are the NMEA-0183 messages handled...

DPT, DBT, VHW, RSA, HDM, HDG, HDT, MTW, VLW, VWR, VWT, MWV, RMC, GLL

Any message type can have its output rate configured or switched on or off by hooking up to a serial terminal and using a simple text line interface. A wacky cable is needed to do that but is easy to make with parts from Maplin, or else everything can be left at the defaults which are sensible values.

What's missing in this limited version are autopilot and route type stuff as found in RMB, XTE and APB messages. If anyone needs those messages I would recommend Frank Wallenwein's device which has more functionality here...

http://www.gadgetpool.de/bestellen/catalog/product_info.php/products_id/29/language/en

I could go to a bigger processor but it would mean an ARM or suchlike as I am at the limit of PICness. That would bump up the price, and as Frank has already done it, I'll leave the higher functionality stuff to him.

Here's a pic of the board...

sdc12357.jpg


and here it is in its box...

sdc12359.jpg


It's all open source as usual. Source, schematics and layout are all here...

http://yappelectronics.co.uk/STN.htm

I haven't written a manual yet. If anyone would like one in any state of build or even just advice on how to do it yourself let me know.

For the complainers - the mods have sanctioned YAPPs in a low-numbers non-profit-making way if they are open source, which they are.
For those worried about CE marking - these devices are not CE marked but I have a dispensation from Trading Standards to share these hobby projects, again in an open source non-profit-making low-numbers way.
Click to expand...

Another handy device.

Now here is a challenge:

My AP computer is a Raymarine SPX30 which uses their fluxgate compass. I won an Airmar GH1283 compass + gps on fleabay last week. It has nmea 0183 and N2k outputs and Raymarine claim the SPX30 isn't designed to work without the fluxgate compass.
So if this turns out to be the case (hope to confirm either way, later this week), I imagine its not feasible to convert HDG to emulate the fluxgate's signals to fool the SPX30?
Ian
PS I gave up on the idea of using the fluxgate with my old Cetrek analogue sensor - (thanks for the yapp you did for me) due to it being useless so far above the waterline (steel vessel) and hence the idea of using a solid state sensor with the SPX30 for the same reason.
 
AngusMcDoon said:
It depends on what the SPX30 compass puts out. Is it analogue or digital?
Click to expand...

Its analogue:

P3 SCRN 0V
P4 Bias Nominal 2.5V dc (VRESET)
P5 F/GA +2.5V dc
P6 F/GB +2.5V dc
P7 Coil drive AC signal, 17 cycles at 7.9kHz, driven twice every 1/16 second

I think it works by measuring phase shifts of the coil drive signal in the two sensing coils which vary with the magnetic field. So no easy.
 
I've just bought a booklet on the raspberry pi, and it set me thinking.

I use a laptop as a chartplotter, and have wires coming from behind the electrical panel through to two serial ports [I have an Expresscard with 2 serial ports].

It would be really nice to have a pi card which would take the AIS and GPS data and broadcast them onto a wireless network.

The major problem that I can see would be getting the laptop to read the data and feed it to the plotter program.
 
Joker said:
I've just bought a booklet on the raspberry pi, and it set me thinking.

I use a laptop as a chartplotter, and have wires coming from behind the electrical panel through to two serial ports [I have an Expresscard with 2 serial ports].

It would be really nice to have a pi card which would take the AIS and GPS data and broadcast them onto a wireless network.

The major problem that I can see would be getting the laptop to read the data and feed it to the plotter program.
Click to expand...

You can of course buy off the shelf products to broadcast nmea data such as those from Shipmodul.com, at a price.

As for reading the data, I use Navmonpc - an excellent free download which can route data to/from serial ports AND its network client to virtual serial ports for use by other software on the laptop. (in my case Belfield chart plotter & Polarview)

I also use its network server on a notebook, to send nmea data from a Shipmodul USB multiplexer to the onboard wifi router so a second laptop in the cockpit can share it.
 
Joker said:
I've just bought a booklet on the raspberry pi, and it set me thinking.

I use a laptop as a chartplotter, and have wires coming from behind the electrical panel through to two serial ports [I have an Expresscard with 2 serial ports].

It would be really nice to have a pi card which would take the AIS and GPS data and broadcast them onto a wireless network.

The major problem that I can see would be getting the laptop to read the data and feed it to the plotter program.
Click to expand...

I had a quick look at a Pi. You need a type B, with Kplex running on it, plus a USB to serial adaptor with which to connect to your nmea data source.
Then a Pi compatible usb to wifi adaptor, or an ethernet cable to a domestic wifi router. (many will run off 12v)
Sounds easy and cheap ! I might have a go over the winter.

The laptop will use Navmonpc to receive the data using its network client option and then route it to a virtual serial port which your plotter program will connect to.

http://www.stripydog.com/kplex/index.html
 
That does seem to do the trick. Sadly, though, looking at all this, I realise that I am sadly out of date. Whereas once I could have programmed a Z80 PIO in machine code, I am struggling with all this
 
Its a long time since I did anything with Linux, so I will give one of these £20 modules a try:

http://www.ebay.co.uk/itm/281082580772

Its a wifi module with RS232 input and a transparent mode. (It may require a Max232 chip to convert ttl serial into true RS232)

If it works it means my Acer notebook nmea server and TP Link wifi router can be retired saving a significant drain on the main battery.

I found the user guide for the module here: http://www.tcp232.net/download/USR-WIFI232-X-V4.4_en.pdf

Transparent mode means it will pipe the nmea data straight out via the wifi path. There is a proviso that no error checking is done, but Navmon does check the nmea checksum.
 
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Thanks! Opened the circuit!
I ordered PIC18F26K22-I / SP, I'm waiting for it when it comes.
Apart from Arduino, I have not programmed anything ... But I hope I succeed :)
 
AngusMcDoon said:
What's missing in this limited version are autopilot and route type stuff as found in RMB, XTE and APB messages.
Click to expand...

I've been searching for am economical way to convert NMEA 0183 of an older Geonav plotter to a ST1000 pilot's seatalk interface for quite some time.

A friend of mine is planing to bring his small sailingboat (Kelt 6.2) to the Med next season and I was playing Santa for him: I found a nice, barely used, old chart-plotter and was able to source a CF card map of the relevant area for it. I've added a nmea 0183 gps receiver to the plotter as the built in receiver has the date rollover bug . And this is already a step forward in modernizing a bit the old Kelt. The amazing thing would be to be able to control his pilot from Geonav (use Track function) but the pilot is an Autohelm ST1000 with what it looks to be a seatalk only interface

I have found this yapp project referenced on several forums and I had high hopes to use it to connect the nmea out of the plotter to the seatalk interface of the pilot. But it appears it is not going to work, or is it ?!

Are you guys aware of any other economical options? One of Frank Wallenwein's devices here Yacht Electronik | gadgetPool would probably do just fine but the cost is higher than the rest of the components combined so maybe not the right choice for this project.

I'm new to marine electronics, I only got a boat for less than a year, so please excuse my possibly wrong assumptions.
 
AngusMcDoon said:
No, it doesn't do the autopilot message conversions.
Click to expand...

Thanks for the quick confirmation, I appreciate it.
I was wandering if the needed conversions can be implemented by reducing the scope of the project (same hardware) to control the pilot only and eventually making it one way (nmea to seatalk)?

I'll probably build this anyway and play with it before giving it to someone who still uses seatalk sensors / instruments. Thank you for sharing your work!
 
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