Solution for Garmin, and probably other incompatable GPS units

[Art]

Hi Guys,
Here is a tested solution to get the Garmin GPS18 PC
to work with the PSP and MapThis! program.

The problem with my GPS18 is that the output is closer
to RS232 standard than desired for this application,
and the GPS transmit line must be inverted.

Lucky only one directional comms is used so a single
transistor circuit is needed that will fit into a DB9 backshell,
or hidden inside an XLR connector.

One of the 1K resistors in the circuit is the usual
resistor in series with the PSP serial Rx line that is used in most
homebrew cables for the MapThis! application.
You can try higher values to reduce the current as
much as can be tolerated before your setup fails,
then lower the value a little to ensure reliable communication.

The 4x AA battery pack is required to power the GPS unit since it
has no compartment for batteries of it's own.
The same battery pack powers this circuit, and since it has a biult
in switch, that can be used to power the GPS mouse on and off.

The GPS18 is a high end unit priced at over $200 in Australia,
and I don't know how many other brand units will have
the same characteristic which is desirable in some applications..

Cheers, Art.

[AlexRoxUrSox]

ITS TRUE! I'VE TESTED IT MYSELF!
Great work Art!
Finally I can put to use my other GPS devices.
Any ideas for an enclosure for the extra resistors and the transistor?

Thanks

AlexRoxUrSox

[Art]

A DB9 Backshell is where I split out the audio, and I fit it in there.
I'll do up a better article with pics if I get the app working reliable.

[AlexRoxUrSox]

Care to take a picture?

[Art]

Here's a pic of my PSP multi I/O cable I made for many applications
including connection to GPS, PC, and Barcode scanner.

The three inline sockets are for PSP audio out left & right, Microphone in, and serial port data recieve and transmit.
Everything is covered in heatshrink.

I used an empty shell from another socket to form the
junction in the middle where all wiring connections are made.

This circuit could be easily housed in that, although I didn't, for compatibility with other devices.

Cheers,
Art.

[AlexRoxUrSox]

Nice work, Art

[Art]

Here's a PSP interface for Garmin GPSMAP 60csx, and probably also the eTrex series, and other Garmin handhelds for hiking.

Power for the circuit is sourced from the PSP serial connector.

http://img201.imageshack.us/img201/9161/garmintopspza3.jpg (http://imageshack.us)
http://img201.imageshack.us/img201/garmintopspza3.jpg/1/w700.png (http://g.imageshack.us/img201/garmintopspza3.jpg/1/)