Help with Serial GPS

Forum 2005-2010 (read only) Hardware Interfacing
1

Ok, so i bought a serial gps unit a while back from ebay for $12 shipped. Its been really cool to play with. I just soldered together the sparkfun rs232 shifter board and tested it out and now I have some problems that I cant seem to figure out. This is what I know:

1.GPS works with computer over usb to serial cable. (both raw serial output console and gps diagnostic programs show good data) :slight_smile:

  1. Raw serial data can be sent to arduino from usb to serial cable then to rs232 shifter board. All data is recieved perfectly. :slight_smile:

  2. When i hook the gps serial up to the rs232 shifter, nothing happens. No tx light on board and no data shown being recieved. :frowning:

  3. the gps specs are 12v power (cigarette lighter), 4800baud, standard NMEA sentences

  4. the only other monkeywrench that could be possible is the use of a male to male DB9 gender changer from radioshack in between shifter board and gps serial cable (both have female ends) RadioShack.com Official Site - America's Technology Store :-/

Im not really sure what to think or how to go about fixing this problem. any input or similar experience would be appreciated

2

anyone?

3

Have you tried to swap the tx and rx pins. see if cross connecting pins 2 and 3 going to the 9 pin connector solve the problem.

good luck

4

It is common for RS232 connections to need a null modem connection (pins 2 and 3 are cross connected instead of straight through) if the connector genders don't match. Try a null modem adapter (or cable) in place of your gender changer.

-j

5

thanks, that was exactly the problem. i dont have a null modem adapter but to test it i just wired it up in the null modem config and it works great!