My best friend (Jim Glover WB5UDE) and I (KD5AMB) have started a

project to create a wireless (802.11b/g) GPS server and APRS tracking

system. It uses a Linksys WRT54G wireless router and the OpenWRT Linux

software. This is the start of what will become a list of projects

using this platform to create Amateur Radio, Wireless, navagation and

network services for your car.

Here is a list of ToDos for this project.

Download and build the OpenWRT project.
Flash the 54G with the new ROM update.
Wire in the two avaible serial ports.
Add GPSD to the OpenWRT project.
Add APRSD to the OpenWRT project.
Build a "pre-configured" version of the 54G ROM with GPSD and APRSD.
Write HOWTO instructions on installing serial ports and using the ROM.
Create a safe power supply from the car's 13.5 volt to the Linksys 12 volts.
volts DC the linksys needs. 
Write article for ARRL.

THIS WILL VOID YOUR WARRANTY.

I have just completed adding the seriall ports to my 54G and here is how I did it.

The LinkSys WRT54G/S have dual serial ports onboard. They are wired out to a header block. This block provides.

The colors listed are for my notes and are the colors in the picture.

Pin 1: 3.3v (Purple)
pin 2:   3.3v (Purple)
pin 3:   Transmit data Tx (gray)
pin 4: Transmit data Tx (gray)
pin 5: Receive data Rx (white)
pin 6: Receive data Rx (white)
pin 7: NC
pin 8:  NC
pin 9:  Ground (black)
pin 10: Ground (black)

Pins 3 and 5 are /dev/tts/0 and pins 4 and 6 are /dev/tts/1.

These signal are at TTY levels (5v) and are not good for driving RS232 signals. To make the signal level I used the 3.3v version of the 232DB RS232 adapter kit from Compsys Workbench.

The pins on the 232DB are:

Looking at the bottom (none chip) side of the max232 board. Pins are marked T/R on the bottom and + on the top side.

vcc 3v (purple)
ground (black)
Trans  (gray)
Recv   (white)