It's never been easier to create adaptive controls to play video games. For gamers with particular needs not met by standard gaming controllers, the Microsoft Xbox Adaptive Controller (XAC) is a fantastic option for managing alternative inputs.

In this guide, we'll learn how to build our own interconnections between large buttons, foot pedals, analog joysticks, and limit switches and the XAC's button inputs.

Assistive Technology Resources

There are many great resources out there for people to learn more about AT for gamers. Here are a few:

• Able Gamers
• Cerebral Palsy Foundation
• Special Effect
• Warfighter Engaged

If you're interested in helping build adaptive controllers, AT Makers can help you get connected with people in your areas. They've also got great guides on building adaptive connectors and switch testers.

The support of Bill Binko of AT Makers, and Bryce Johnson of Microsoft Devices have been incredibly helpful in creating this guide! Thanks guys!

If you're just learning about XAC, here are a couple of good videos to watch:

Parts

You'll need to a Microsoft Xbox Adaptive Controller as well as an Xbox One or Window's 10 PC to use this guide. Additionally, here are some of the switches, buttons, joysticks, pedals, wiring, connectors, and supplies you can use to create your own inputs:

You can also have a look at our many, many other buttons!

Tools

Here are some useful tools for use when making adaptive tech inputs:

If you're new to the Xbox Adaptive Controller, have a look at these resources:

• All about the Xbox Adaptive Controller
• Getting to know the Xbox Adaptive Controller
• External devices with XAC
• FAQ

If you need to dive into deeper details, check out these Xbox Adaptive Controller Input Specifications. These are incredibly helpful in detailing the pinouts and voltages for all of the ports, particularly the analog ports for joystick control.

The XAC works just like a standard Xbox controller in terms of wireless connection with the Xbox, however it only sports a few of the typical buttons -- D-pad (6) , A button, B button, menu (3), Xbox button (1), menu button (3), and view button (2).

All of the missing inputs, along with the ones already physically present, can be controlled by external devices plugged into the 3.5mm jacks along the back of the XAC.

For example, you can see here that the Y, X, B, and A buttons are all represented as 3.5mm jacks, where you can plug in four larger buttons if needed.

Thanks to the Copilot Mode, you can use a standard Xbox controller in tandem with the XAC, so two users can work together as a single player, or one use can use both if that suits their needs.

Next, we'll look at the standards used with these jacks so you can interface your own digital buttons, switches, and analog devices with them.

Digital Input Standard

The 3.5mm inputs jacks on the XAC allow you to connect any type of switch that can open and close a circuit between the internal Ground and a 1.8V pin that is internally read on the device. These pins have internal-pull up resistors, so you can think of them just like you do any switch used in a microcontroller project.

These jacks are a standard stereo audio-type jack, and have Tip, Ring, Sleeve (TRS) connections. However, only Tip and Sleeve contacts are used.

So, in order to press a button on a digital input port, we simply need to ground the tip to the sleeve.

Represented another way, we can see that the Tip and Sleeve wires coming from a typical stereo cable can be shorted via a switch or button to create the connection that signal a button press.

Analog Input Standard

There are four jacks on the XAC that can accept variable resistance analog inputs, such as potentiometers -- X1, X2, LT, and RT. These map to the left thumb stick, right thumb stick, left trigger, and right trigger.

In order to read dual potentiometers and provide ground and reference voltages, these ports require the use of a four-pole TRRS plug. This is what is commonly found on mobile phone earbuds that include a microphone.

This is how the connections are used:

• Tip = wiper output from potentiometer 1 for X axis
• Ring 1 = wiper output from potentiometer 2 for Y axis
• Ring 2 = Ground
• Sleeve = 3.3V reference voltage

Here you can see two potentiometers from a typical analog joystick connected to the proper poles of the TRRS jack. Note, one potentiometer is inverted to provide the proper orientation of signal values as used on most joysticks. This isn't of too much concern however, as values can be remapped in software configuration on the game console.

Now that we understand how the inputs work, let's wire up some components!

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.

Terminal Block Jack to Cable Plug

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.

Switch to Terminal Block

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.

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.

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.

Light Touch Limit Switch

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.

Foot Pedal

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.

Hefty On Off Switch

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.

Soldered Wire Connections

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.

Analog inputs are a bit more complex than digital. They require either one or two variable resistors to be used as triggers or thumb sticks, respectively.

Let's add a joystick to the X1 or X2 ports, which can control the two thumb sticks. This joystick is really just a pair of potentiometers, one for the X-axis that is controlled by horizontal movement of the stick, and the other for Y-axis motion achieved through vertical motion of the stick. It's capable of mixing those motions to partial values of both potentiometers simultaneously for smooth motion, and has a spring return to bring it to center when you let go.

From our previous look at the XAC Standards we saw that we'll use this following connection schematic:

Again, note how we're reversing the direction of the second potentiometer to mimic the value behavior of a typical joystick.

Wiring

We'll first connect the ground and reference voltage tabs of the pots so we only need four, not six wires.

Next, we'll use four long lengths of silicone sheathed stranded wire. These are color coded for ease of explanation in this guide, however, they are unruly and could get tangled easily, so you would want to use some wire loom to neaten them, or get some appropriate four-conductor wire for your own use. (Old USB cables can be a very good source for this once you cut off their ends!)

Add Terminal Adapter

Now, screw in the four wires as shown. Ignore the markings on the adapter, those refer to the expected use as a stereo + microphone adapter, not a joystick for the XAC!

Plug in the joystick to X1 or X2 on your Xbox Adaptive Controller and you're ready to play!

As you can imagine, every gamer with assistive tech needs will want potentially unique solutions, so this is just a small set of possible controls you can build, and some of the fundamental techniques for getting started.

USB Inputs

As mentioned previously, this guide does not go into USB HID joysticks, but there is some work being done by Bill at AT Makers and our own Dan Halbert to bring CircuitPython HID joystick drivers into use with the XAC and Circuit Playground Express boards. Stay tuned!