How to make a USB GPS Charging cable
GPS USB charging cable for DConnex DC-230 and Seidio G2500
Jay Modha 30th August 2004

DISCLAIMER - If you damage your GPS Unit/PDA/PDA Mount/Car etc etc by doing this don't blame me!

 
Like many of you, Iíve been looking around for a good way to be able to use my PDA as a navigational device in my car. The specific GPS device I got was a DConnex DC-230 from eBay and since this was a Bluetooth device it paired up nicely with my ipaq 4150 as it also has Bluetooth support.

Now, most of the journeys I take are more than an hour so I wanted the ability to charge my ipaq and my Bluetooth GPS device at the same time. The GPS device that I have, is charged via a USB cable; unfortunately I couldnít find any PDA mounts that supports charging a PDA and also a GPS device via USB.

The closest thing I found was the Seidio G2500 which has the ability to charge my PDA and also has a 5V DC output. So I decided that I would make a cable that has the appropriate connection to interface with the Seidio G2500 5V DC output and the GPS unit.

I figured that I wouldnít be the only one who will run into this type of problem so here is a tutorial of how I did this.

Now, I couldíve been lazy and got a splitter for my cigarette lighter and powered both my PDA and GPS unit from that, but I didnít want a mass of cables in my car so I decided to go for this more time consuming but nevertheless cleaner way of charging both devices with the least amount of cables.

 
Step 1 - Things you will need to complete this project
 
I sourced all of my stuff from Maplin Electronics, but Iím sure youíll find similar products from your local electronics retailer. Unfortunately I couldnít find the correct type of 4.0mm jack that could be wired straight into the USB cable so I had to wire it into a 2.5mm line socket and then connect a 2.5mm power plug into the USB cable.


Fig 1.0

Figure 1.0 shows the items you will need to complete this project. The items shown (from left to right) are the DConnex Bluetooth GPS receiver (with mini Type-B USB connecter), USB cable (Type-B connector on one end and regular USB connecter on the other end) Seidio G2500 PDA Mount, Power adapter lead & 4.0mm DC connecter, 2.5mm line socket and 2.5mm DC power plug.

Please keep in mind you will also need some wire cutters, soldering iron and a multi meter (optional).
Fig 1.1 Fig 1.2
Fig 1.3 Fig 1.4
Figure 1.1 shows a close up of the Seidio G2500's power connecters, (from left to right) the first power connecter is used to charge the PDA and also supply the voltage for the DC/OUT connection. The DC/OUT connection is where our new cable will be plugged in to charge the GPS unit.

Figure 1.2 shows the DC connector that you will need to plug into the Seidio G2500's DC/OUT connection. You will use this connector along with its matching power adapter lead (Fig 1.3) to connect with 2.5mm line socket.

Figure 1.4 shows a close up of the GPS receiver.
Fig 1.5 Fig 1.6
Fig 1.7 Fig 1.8
Figure 1.5 shows the rear of the GPS receiver, the port labeled "DATA" is where the USB cable shown in figure 1.6 will be plugged in.

Figure 1.7 shows the 2.5mm line socket, the power adapter lead show in in figure 1.3 will be wired into this socket.

Figure 1.8 shows the 2.5mm DC connecter, this will be wired with the USB cable shown in figure 1.6 (the larger USB connecter will be cut off in place of this connecter) which in turn, will be plugged into the 2.5mm line socket shown in figure 1.7.

 

Step 2 - Connecting the power adapter lead to the 2.5mm line socket
 
Depending on where you place the GPS unit in your car, you might want to trim the power adapter lead so that there is not so much slack. I opted to do this, because the USB cable was going to be long enough to allow me to place the GPS receiver wherever I wanted. You will notice that the power adapter cable actually consists of two cables, one which is solid black, and another which is white and black. For the purpose of this tutorial, the white and black wire will be negative and the black wire will be positive.

When you unscrew the 2.5mm line socket, you will notice that it has two connections where the wires from the power adapter lead will be soldered onto. The connecter that is on the outside of the 2.5mm socket is for the negative wire and the connecter that is in the inside of the socket is for the positive wire.

After you have soldered the wires onto the 2.5mm line socket, you should have something that resembles figure 2.0 below.

IMPORTANT: Please make sure to insert into the power adapter lead the outer casing of the 2.5mm line socket otherwise you will not be able to put it back on once the wires have been soldered.


Fig 2.0

Step 3 - Connecting the 2.5mm DC power plug to the USB cable
 
Unscrew the 2.5mm power plug and you will notice that like the 2.5mm line socket, this also has two connections to where the USB wire will be soldered onto. The same principle applies here, the inside connection is for the positive wire and the outside is for the negative. Figure 3.0 shows the connections for the 2.5mm DC power plug.


Fig 3.0

The USB cable shown in figure 1.6 will need to have the regular sized USB connector removed. This can be done with a wire cutter. Once this is done, you will need to strip the outer cabling to expose the wires inside. Figure 3.1 shows what you should see when this is done.


Fig 3.1

You might find there is some shielding around the wires, this can be removed to expose the four wires inside the cable. The two wires which we are concerned with are the red and black ones. The white and green wires can be trimmed down so that they do not get in the way. Once this is done, simply solder the red wire to the positive connecter of the 2.5mm plug and the black wire to the negative connecter.

Figure 3.2 shows what you should be left with once you have soldered the wires.

IMPORTANT: Please make sure to insert into the USB cable the outer casing of the 2.5mm plug otherwise you will not be able to put it back on once the wires have been soldered.


Fig 3.2

Step 4 - Connecting it all together!
 
Below are the steps to connect all the plugs and wires back together and into the PDA mount.
First, connect the power adapter lead to the 4.0mm
DC power connecter
Next, connect the 2.5mm DC plug of the USB cable
to the 2.5mm line socket of the power adapter lead.
Then connect the mini USB connecter of the USB cable to
the GPS unit
Finally, connect the DC power connecter to the PDA's
DC/OUT socket
With everything connected your setup should resemble figure 4.0.


Fig 4.0

Conclusion

With everything connected together you should hopefully have a fully working USB cable that will charge your GPS unit (Or any other type of USB device) from the PDA mount. It's always safe to check that the voltage output does not exceed +/- 5V DC by using a multi meter.

I hope you found this tutorial helpful, let me know how your installation goes or if you have any recommendations to improving this. You can contact me via email jmodha@3ill.co.uk