Cannibalize USB GPS puck for input to DSC VHF?

dutyhog

dutyhog

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Does anyone know if I can cannibalize a USB GPS puck for input to a DSC VHF? It's a Standard Horizon GX1200E, and I have a spare BU-353 GPS puck. Assuming I can cut off the USB plug and provide earth and 5V from somewhere to the appropriate cable strands, will the remaining two strands deliver NMEA0183 directly or do they need software such as in computer drivers?
 
I'll let someone else give a more technical answer, I dont think there is a way to do that. If there was I guess you'd need some sort of interface between the GPS puck and the Radio.
 
I seriously doubt that you could configure it to drive an NMEA0183 input directly from the USB cable - USB is a serial signalling system, but a long way off the RS232/422 that NMEA requires. I'm sure that there will be connections inside the USB puck that do carry serial NMEA2000, but finding them and making connection to them would be no mean feat.

reasonable GPS modules are available for less than a tenner these days - see http://www.ebay.co.uk/itm/GPS-NEO-6...348120?hash=item5d6be85a58:g:HEIAAOSwjqVZEdwt. It should be simple to use - power in on two wires and NMEA in/out on two more. Admittedly, it expects 5v, so you'll need a power regulator, but the USB puck will also be expecting a 5v power supply. I use a HobbyWIngs UBEC (http://www.ebay.co.uk/itm/Hobbywing...594331?hash=item339bb3f55b:g:rUAAAOSwvg9XbtnT) which is very successful at a very reasonable price.
 
As Maby says, NMEA0183 is an antiquated system based on RS232 or in its later versions RS422. USB is much more recent. Totally incompatible for direct interfacing.

You could stick something in the way to interface the two, but that would cost a fair bit more than just getting another cheap GPS source that is compatible with NMEA0183.
 
No the USB puck won't work. However, a PS/2 type GPS puck will and they're still a lot cheaper most mushroom type antennae. I used one and powered it with a 5v supply taken from a 12V USB adaptor.
 
While everyone is right, I suspect they may also be wrong!

So you can't just take the D+ and D- Data feed off the USB and connect it because the USB protocol won't work. BUT there is a fairly high chance that inside the puck is a Serial to USB convertor. If its identifiable, and you can find the inbound data feed to it then you could simply bypass it...

Back in the day all these units were serial. Then the USB port arrived and people didn't have COM ports so people started using COM to USB Convertors. I know that at least some of these units then just put the convertor inside the puck. The clue would be how it installs on Windows. If it installs like a COM Port then its almost certainly going to have a USB to COM port adaptor inside it. Opening it up and taking a photo and posting it either here or on an electronics forum may well find someone who can spot the chip and then with some luck its as simple as following the traces back...
 
ShinyShoe said:
While everyone is right, I suspect they may also be wrong!

So you can't just take the D+ and D- Data feed off the USB and connect it because the USB protocol won't work. BUT there is a fairly high chance that inside the puck is a Serial to USB convertor. If its identifiable, and you can find the inbound data feed to it then you could simply bypass it...

Back in the day all these units were serial. Then the USB port arrived and people didn't have COM ports so people started using COM to USB Convertors. I know that at least some of these units then just put the convertor inside the puck. The clue would be how it installs on Windows. If it installs like a COM Port then its almost certainly going to have a USB to COM port adaptor inside it. Opening it up and taking a photo and posting it either here or on an electronics forum may well find someone who can spot the chip and then with some luck its as simple as following the traces back...
Click to expand...
Did you watch the YouTube 1 post above yours? ;)

The bu 353 usb unit looks identical to the br 353 serial one, so agree, fairly certain there'll be a usb/serial chip in there. And maybe some handy pads to solder onto like the on in the youtube.

http://usglobalsat.com/images/product/large/57.jpg
http://usglobalsat.com/images/product/large/62.jpg
 
£42!!
For a serial to USB Convertor!

As its bi-directional it might actually work! If you had one lying round fair enough to try it but the plug is a male as will be your puck so there would be the next issue... But it seems an inefficient way to do things anyway as that is effectively what I was saying is in your GPS so you'd be going GPS Serial -> USB -> Serial. Multiple points of failure! And that's if it works. If you were spending £42 buy a solution that works (PS-2 Puck)

I hadn't watched the video - thought it was decoding the USB using an arduino - but it was just using the arduino as a way to display the COM Port data that it was pulling directly from the pins.
 
dutyhog said:
Thanks for all the advice so far. I'll open the device and get a photo to post.
Also I've found a USB - NMEA adaptor at http://digitalyacht.co.uk/product/adaptateur-nmea-usb/and wonder if that would work.
Gordon
Click to expand...

You really are in danger of over complicating things here and wasting money! Forget the USB interface - it will be a nightmare to get the interface going. If you really have no further use for the GPS module, by all means pull it open and see if you can find the basic NMEA0183 signals inside it - but that is likely to be difficult without access to more sophisticated electronic instruments than your question leads me to believe that you have. Even if you find them, making the connections is likely to be very difficult - it will probably use miniature surface mount devices with very close pin spacing and making connections to them without laboratory grade tools likely to also be very difficult.

Assuming that your radio will accept TTL level NMEA0183 signals rather than insisting on the RS232 levels that are part of the NMEA specification, then you should be able to use any of the little GPS modules that are sold on eBay for inclusion in model aircraft and drones. You should be able to get a perfectly serviceable UBlox module for less than £20 - if you purchase from China and don't mind waiting two or three weeks, then they can be had for less than £10. Even if the radio does require proper RS232 signals, going via the cannibalised USB stick will not make your life any easier - it will certainly be using TTL level signalling and you will have the same electrical interfacing issues as you would with a UBlox module as well as working with minute, undocumented components.
 
There are plenty of GPS modules on ebay, look for ublox, as that assures documentation can be found.
You might need a buffer or inverter to drive the RS232.
IF you can read the chip numbers on the GPS puck, you may find the main chip is a GPS chip like some of the Ublox ones which have both USB and TTL built in.
Unfortunately hacking into the pins of modern ICs can be difficult or impossible....
 
Its possible that the nmea 0183 serial to usb serial is done by a chip the usb plug. (there are many serial to usb leads which are exactly like this for use with Arduinos etc)
This would mean that if you cut off the plug, the Nmea serial data maybe present on one of the wires but you'd need a pocket scope or similar to identify it.
 
You need for your radio a GPS with Nmea (Rs232) and 4800 baud.
The serial GPS these days are usb or ttl for the mulicopters and they have min 38400 baud, 3.3 -5 volt supply voltage and ttl output. In order to use one of them you need to reprogram to 4800 ( for that you need an interface USB-NMEA or RS232) for your computer , a stepdown regulator 12Volt to 5 Volt and a level converter ttl to Rs232.
Since you are not familuar with these components buy your self one of the ready made GPS domes (Evermore SA-320).
I use one of these modified multicopter GPS´s puck ( Voltage regulator and Level converter) but I am a professional electronic engineer.
 
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Frankklose said:
You need for your radio a GPS with Nmea (Rs232) and 4800 baud.
The serial GPS these days are usb or ttl for the mulicopters and they have min 38400 baud, 3.3 -5 volt supply voltage and ttl output. In order to use one of them you need to reprogram to 4800 ( for that you need an interface USB-NMEA or RS232) for your computer , a stepdown regulator 12Volt to 5 Volt and a level converter ttl to Rs232.
Since you are not familuar with these components buy your self one of the ready made GPS domes (Evermore SA-320).
I use one of these modified multicopter GPS´s puck ( Voltage regulator and Level converter) but I am a professional electronic engineer.
Click to expand...

Agree it's a lot easier just to by a rs232 serial output puck, though if you fancy rolling the sleeves up a bit then all the conversion can be done with a cheap arduino or similar with a ttl/serial adaptor & power supply. Couple of quid each on ebay. Arduino can act as multiplexer as well using software serial to get ais.

Not really a lot of point if you don't enjoy some fiddling. :)
 
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