GPS USB -> RS232 serial?

[pskhaat]

I'm old school in the computer world, if it can't be edited and managed by vi on a vt100 terminal it's worthless. USB is for punks.

My GPS receiver has a USB (male A?) cable. But I'm writing software to read NMEA on rs232 serial. All the adaptors go from rs232 to USB. I need it the other way around to take my Magallan USB cable into my rs232 port.

Does anyone have any pointers on how to do the conversion, or links to some converters?

[k6uk]

Unfortunately, there isn't an adapter that works the other way around.
So, you'll have to get creative.

Do you need to be able to send and recieve data from the PC, or is the PC just listening to the NEMA strings.

What GPS reciever do you have?

Could you install a usb port (cards, PCMCIA?) or is this out of the question - because you could use a driver that makes the USB port appear to your software as a standard RS232 connection.

-Mike

[pskhaat]

What GPS reciever do you have?

Right now an Magellan Explorist 210 which is only USB. As for a driver, I'm unsure. I have written some Java software to parse and store the NMEA sentences from serial ports, but as mentioned Java is at fault (so am I) with the whole `Univseral' in USB irony.

I guess I could get some stuff to make USBs appear to be rs232 ports, but then my software will start setting baud rates, etc :(

I must rethink. I wanted this to go to all platforms, but I may just make this a Linux solution...

[DaveInDenver]

Well, how handy are you? I hacked a little USB to TTL adapter so that I could program my VX7R handheld. I had a Prolific PL-2303 USB-RS232 chip and it worked well because it could source +/-5V without an external driver. This is just barely legal in the RS232 spec (which is a min 10V swing), so it worked. I was going USB to serial, but there's no reason I could see that it would not work electrically the other way. It's a full duplex chip for both buses, would do all the fancy USB remote wake-up and configuration (I just left the default USB config). I do wonder though about a master, since the GPS is probably a slave only. You'd need a host somewhere on the bus. So the box you build would probably need to have a controller, which typically means a uP and some software.

Most HCDs are computers, although my next thought is a USB thumb drive. Those little suckers look like a host PC with a filesystem and everything. IOW, you are configurating a little mini network among two peers when you plug in a $5 thumb drive. I'd bet if you break one open you'll find all the hardware you basically need to make a USB host. You /might/ need a USB-RS232 chip as well, since there's probably no provision for a serial port built in. But it couldn't be that hard. The Prolific chip I found was scavanged, but FTDI makes an close equivalent (the FT-232R). For one piece, I'd just call the manufacturer and ask for a sample, but the chip should be like $3 or $4 from Mouser.

[Robthebrit]

Do Garmin USB devices even use NEMA any more? I was under the impression that Garmin only used NEMA on RS232 devices and all the USB devices spoke Garminese.

On Windows its quite easy to open a USB device and receive data from it, its very similar to serial communication but you either need to obtain the named port or open the driver directly. The resulting code would be Win32 specific.

I documentation somewhere on Garmins custom USB formats. Let me dig through stuff..

Rob

[crawler#976]

I'm cunfuzzed...

do you need to go from a 9 pin (or 21) to USB? Or USB to 9 pin?

I use a 9 pin to USB cable on our older equipment. Seems like there should be a way to hook it up with a couple adapters or a null modem???

http://www.cablestogo.com/product.asp?cat%5Fid=1501&sku=26886&engine=adwords!654&keyword=%289+pin+to+usb%29

[pskhaat]

Nope, the other way around, USB device into a serial connection.

[pskhaat]

Dunno about Garmin, Magellan still provides NMEA. Can't want to support Garmin when they go against established standards.

[Robthebrit]

Scott (pskhaat)

you may already have this info but here it is for everybody else:

http://www.garmin.com/support/commProtocol.html has all the info for reading Garmin format GPS data over rs232 and USB, there is also a section of garmin NMEA extensions. Handling the GPS in its native speak over USB is not simple, there are lots of caveats you need to handle.

There is also https://www.garmin.com/DeveloperZone/ which is mainly for appicatin development on Garmin integrated PDAs.

Rob

[oldcj5guy]

I may not be understanding what you are looking for, but is this it?

http://www.mountaingear.com/pages/product/product.asp/item/100222/N/0/cmpn/70130/CMP/KNC-70130/afl/436

I use one of these:

http://www.usbgear.com/USBG-232MINI.html

Might be able to take one apart to build your own setup, but as it already communicates into the serial port there may be no need for your application.

[oldcj5guy]

guess I should pay more attention to dates when i'm in search mode and decide to reply to something....

[pskhaat]

http://www.usbgear.com/USBG-232MINI.html


Problem is these are for computer who have USB ports. My interfaces don't they only have RS232, this how to connect commodity GPS USB equipment through native RS232 ports.