Interfacing buttons and switches to the XAC's 3.5mm digital input jacks is incredibly easy to do! We only need a way to connect a given button or switch to a 3.5mm mono or stereo cable.
The simplest way to connect most buttons and switches is through a 3.5mm stereo audio jack terminal block. Once you connect it to your button, then you can simply run any 3.5mm stereo cable between it and the chosen port on the XAC.
Here we see the connections needed:
- N.O. switch to Adapter L (which will contact plug Tip)
- Common switch to Adapter Gnd (which will contact plug Sleeve)
Optionally, to keep compliance with other adaptive technology devices other than the XAC that use 3.5mm TR mono jacks, it's a good idea to short the Adapter R contact to GND. This isn't necessary for the XAC, but good practice.
Here's an example of connecting a large arcade button to the terminal block, using quick connect wires. This is a nice, secure connection that requires no soldering.
Quick Connect Wire to Terminal
Use a small screwdriver to bend in the two metal crimp ends a little bit so they can be pulled from the plastic connector housing, we won't be using it.
Unscrew the terminal block screws to open the terminals fully, then insert the blue wire into the GND terminal and the white wire into the L terminal.
Screw down the terminal screws moderately tight.
Quick Connect Crimp Connectors to Switch
Now, slide the white wire crimp terminal connector to the N.O. spade terminal of the switch.
Connect the blue wire to the Common connector
Plug one end of a TRS 3.5mm stereo cable into the adapter
This button is now ready to be plugged into any of the digital input ports on the XAC and used just like any Xbox controller button!
We'll give it a nice home by re-using a cardboard box as a button housing.
Decide where the button will go, then trace the inside of the plastic button shaft nut.
Cut out the hole with a hobby knife.
Insert the button and push down a bit to make marks with the registration shafts, then poke those holes out with a small screwdriver.
Insert the button, then thread on the nut from the inside of the box.
Add Switch and Wire
Place the switch into the shaft and twist to lock into place.
Add a small hole in the back of the box for the cable.
Plug the cable in through the box and into the adapter.
Add strain relief with a zip tie.
The button and box are ready to go, time to plug it in and test it out!
Here, we're plugging it in to the X button jack on the XAC.
You can use this method with any type of switch or button. Here are a few other examples.
The switch shown takes very little pressure to activate, which may make it good for adapting to chin or mouth activation (with appropriate adaptation) as well as light pressure activation from other sources.
The Adafruit foot pedal has a good activation switch inside and can be easily wired to a TRS plug.
To use the footswitch as a normally open, momentary switch, simply connect the white wire to the Adapter GND terminal and the red wire to Adapter L. You can leave the black wire unconnected.
If you have a reason to use it as normally closed, so that a button is pressed constantly unless you tap the switch, use the black wire in the L terminal and ignore the red wire.
This one is unique in that it is not a momentary switch, but instead latches in the on or off position. This may be useful for cases where the player wants to "hold" a button for long periods of time, such as an accelerator pedal in a driving game, and doesn't plan to "feather" the throttle too much.
Open the case with the thumb screw and remove the top.
Wire from the Adapter L and GND positions to two terminals across each other in the switch.
Tuck in the wires neatly so the don't impeded the button mechanisms, and place the adapter in the case cutout (remove plastic plug first).
Close the case and replace the thumb screw.
Plug in a 3.5mm stereo cable.
In cases where you want a soldered connection, you can use the 3.5mm stereo pigtail cable instead. It has pre-tinned wires to solder to your buttons and switches.
Use a multimeter in continuity mode to determine which wires are tip and sleeve, then solder those two the NO and GND of your button or switch.
In this case, the red and white wires are tip and sleeve, and we'll ignore the copper non-insulated wire (it can be trimmed or bridged to sleeve).