.: Connecting a trackball and spinner to a single USB mouse

This write-up is to show how to connect both a trackball and spinner to a single USB mouse interface.  Although this example shows the use of the Oscar Controls USB mouse interface and spinner, most any USB mouse will work (except Logitech!)  The following components were used:

You'll notice that I use various connectors to make a custom wire harness.  These aren't necessary if you would rather cut off plugs and solder wires directly to the contacts.

The rocker switch is used to switch the x-axis signal output of either the trackball or spinner to the mouse.  This ensures that only one device is active at a time.  Note that the trackball will always control the y-axis of mouse because it is connected directly to the mouse.  The DPDT rocker switch's center lugs are connected to the mouse, and the lugs on the ends connect to spinner and trackball.

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If you are using your own mouse, the center lugs on the rocker switch should be connected to the outside pins where the x-axis black phototransistor is on the mouse board.  More in-depth examples of basic mouse hacking can be found here: http://www.members.shaw.ca/bakaye/tballhack.htm, and http://mamewah.mameworld.net/mousehack.html.

Making the wire harness

The first step was to build the wire harness.  As mentioned above, the connectors aren't necessary if you are making a "permanent" setup, but I like to try to keep the individual components easily removable. 

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Here is the pinout for the Happ trackball.  I believe that the Wico and Betson Imperial trackballs are the same, but you should verify yours before following this diagram.

The +5V and Ground wires for both the spinner and trackball are twisted together and crimped together with a .250" spade terminal.  The spade terminals are then used to plug into the wire taps that were connected to power leads from the PC power supply.  Do not make these connections to your PC's power supply with your computer turned on!!

Final connections

The trackball y-axis leads are connected to the USB mouse, and the center lugs from the rocker switch are connected to the x-axis of the mouse.

Next connect the spinner and trackball x-axis leads to the upper and lower lugs on the rocker switch.

Verify your connections with a multi-meter to ensure all your connections are correct.

Turn on your PC and wait until Windows is loaded.  Finally connect your USB mouse to an open USB port on your PC, and your mouse will be automatically detected.  You should now be able to switch between the trackball and spinner by using the rocker switch.  That's it!

Any questions?  Please email Email for information.