YAPP GPS mouse to DSC VHF interface

[AngusMcDoon]

Do you have a shiny new DSC VHF radio that needs a GPS position input in NMEA 0183 format, but don't have a suitable data source? Or do you want an independent position source for your radio in case your main one goes wrong? This is a question that is often asked on this forum, and a common answer is to use a Globalsat BR-355 serial GPS mouse that provides the correct format information. They are available for about £25, for example...

http://www.ebay.co.uk/itm/GlobalSat...ics_GPSSystems_GPSSystems&hash=item257fc29925

However, they come with a daft connector, and need a 5V supply. So here is the solution - a dumb interface box with a 5V power supply built in. There is no processor or software in this YAPP, which is a first, it's just a circuit board, a few components, and a neat box. Here it is modeled by Owl...

It has connectors for 12V power and ground which can come from the same supply as your radio so they are switched on together, data out and ground to go to your VHF NMEA input, and a 3 way connector to the GPS mouse which you wire in after cutting off its daft connector and stripping the wires. The circuit board sits in a handy bulkhead mountable box. Here it wired up...

The box handily has entries for the 3 wires and 2 mounting holes. The BR-355 works fine inside the cabin of a GRP boat, so the whole lot can be shoved behind your switch panel out of the way. The box is not waterproof.

The output from the BR-355 is the usual NMEA guff and looks like this...

$GPGGA,203826.000,5311.5252,N,00245.8847,W,1,07,1.7,28.1,M,49.2,M,,0000*70
$GPGSA,A,3,19,03,06,27,22,01,11,,,,,,3.4,1.7,2.9*31
$GPGSV,3,1,12,19,80,150,21,11,52,266,26,03,51,147,29,27,47,133,22*77
$GPGSV,3,2,12,22,47,071,20,06,35,134,32,01,31,256,29,28,20,320,16*7C
$GPGSV,3,3,12,18,19,047,,14,13,109,,32,13,195,20,08,10,287,*7F
$GPRMC,203826.000,A,5311.5252,N,00245.8847,W,0.19,46.05,050713,,*25
$GPGGA,203827.000,5311.5252,N,00245.8845,W,1,07,1.7,28.2,M,49.2,M,,0000*70

If anyone would like one, assembled with the box, send me a PM. They cost me about a fiver to make and post, but usual thing, make a contribution that covers my costs and anything else you think its worth.

I seem to remember that the BR-355's data rate defaults to 38400 and needs to be changed to the more normal 4800 with an app that is available on their website. It's a while ago since I got mine. Can anyone confirm?

 

[NorthUp]

Bumped, and a pm on the way...

 

[stephencox]

The spec sheets all seem to say 4800 data rate which is the NMEA 1830 standard.

Stephen

 

[AngusMcDoon]

The spec sheets all seem to say 4800 data rate which is the NMEA 1830 standard.

Stephen

Yes, I found this...

http://www.usglobalsat.com/store/download/57/br355_ds_ug.pdf

I have another one from a different manufacturer. Maybe it was that one I changed. I remember changing something once.

 

[Keith-i]

I like the little box you've used, is that from rs or someone similar?

 

[prv]

Excellent! Sadly I made my own version on a bit of veroboard a few months ago, so I don't need this, but I'm almost tempted to buy one anyway as it's much neater than mine!

Until the manufacturers finally get a clue and include a GPS in the radio, this is the answer for DSC position information. None of this having to turn on a plotter business - the radio should be self-contained.

(I know there are one or two radios out there that have built-in GPS, but the vast majority don't.)

I seem to remember that the BR-355's data rate defaults to 38400 and needs to be changed to the more normal 4800 with an app that is available on their website.

Not mine - it worked straight out of the box.

Peter

 

[laika]

Like other's I'll say "nice project" but I'll especially add "Nice owl".

My primary GPS is the one in the plotter but I bought a globalsat GPS as a backup. Tested it OK with the radio but it's been waiting to be wired up for a year. Ideally I'd like a single switch to switch between the NMEA outs on the plotter and the GPS *and* turn on the power to the GPS, but have been dragging my heels locating a quad pole double throw switch: I think that's what I need but I'm no cop at this electronics stuff.

My power supply is a butchered and poorly re-soldered cheap phone charger. Is the YAPPPsu (Is that some form of sushi?) a straight forward voltage divider, in which case how does it compare with the phone charger solution? I'd throw in phrases like "buck converter" but for all I know that may be the US equivalent of that place where people fence stolen goods.

 

[AngusMcDoon]

Is the YAPPPsu (Is that some form of sushi?) a straight forward voltage divider, in which case how does it compare with the phone charger solution?

This YAPP, like all now, uses a LM2931 voltage regulator. This is an automotive load dump kind. What this means is that it can handle the noise and voltage spikes that are found on automotive and marine systems with solenoids, starter motors, altenators and other unruly equipment. A voltage divider would pass these through. A phone charger would be similar.

 

[nigelmercier]

This YAPP, like all now, uses a LM2931 voltage regulator...

Have you considered going the SMPS route? The controllers seem to be getting easier to use now.

 

[AngusMcDoon]

Have you considered going the SMPS route? The controllers seem to be getting easier to use now.

I'll consider anything that is cheap like me