Electronic Circuits and Projects Forum

Hello, I recently purchased a Garmin 18x LVC GPS unit to use with my micro controller. I am using a PIC18 with to communicate to the GPS unit and hyperterminal to see the data. Now I am running into some problems. For one, I am very new to GPS, this is actually the first time I am working with one and I have no idea if this unit is on or off because I am not receiving any data from the unit even after 5 minutes.

Now for the controller, as I said I am using a C-Stamp micro controller that uses a PIC18. I am not sure if anyone on this forum is familiar with that controller but it has its own syntax for sending/receiving info. I am using two simple lines that SHOULD receive any data from the GPS unit but it is not. I a, also using MATLAB and the C18 compiler.

I have a few questions now as well...

For the GPS Unit does anyone know if you have to initialize the system? I have been trying to send it a string of $PGRMC,0D0A which should echo back to me. I also read that I need to end each line with return and line feed and those are the corresponding hex values for that at the end.

Any help is welcome. I just need to get this working!

Yes, quadruple checked that. Right now I have an RS232 -> USB connection from the controller to my laptop. I also have the pins that use that connection hooked up to the GPS unit. I am thinking that maybe I cannot share the connection? Otherwise yes everything is connected correctly.

You should be able to hook the GPS to your PC and see the data in hyperterminal. Most (I think all) GPS units default to outputting a position string every second and so you shouldn't have to send it any commands. To connect to a Pic you will need a MAX232 chip to invert and level shift the signal.

Mike.

You could use Mike's method. Clicky.

Mike.

Alright I tried connecting the GPS Directly to the RS232 cable to see if I can get anything on the hyper terminal, and there was nothing showing. I am uncertain as to what I am doing wrong...

Does the db9f shell contain the BJT's or does one have to go out and make the circuit? Like can I go to radio shack tomorrow (oh god did I really say that when tomorrow is black friday!?!?) and buy one so then I can hook it up and have it working successfully? Also will a simple amp be good enough to boost the signal? I believe that the GPS outputs 5V.

Sorry for the stupid questions but like I said I am a programmer kinda guy, worked a little bit with circuitry so I know how to wire something up but when it comes to specifics... Well they just don't teach that that much in school