If you only need the 16 GPIO buttons, see the V1 - it's more compact and costs less.

We've pre-installed the inimitable GP2040-CE firmware and configured it for all the buttons on a common gaming controller.¹ You could game with it, but that's not the point here; rather, as a standard DirectInput USB-HID device requiring no driver, the buttons can be read by software as easily as keyboard keycodes, making for a simple, ideal, miniature generic controller.² Whether as a software-specific interface, a robotic input, or a custom keypad, you'll probably be able to get this little doohickey to do nearly anything you can think up, without having to fiddle with serial/I2C/SPI interfaces for button matrices or a host shield like an Arduino.³

The GP2040-CE firmware is truly highly-customizable, with far too many functions to list, and really simple to program through a point-and-click web interface. Definitely have a look at their website. A few things we can recall:

• button macros: assign a series of keys, or a keychord, to a single button press
• multiple layouts: switch between your multiple customized layouts with an assigned key combo
• rapid fire/turbo: fire a key N times with a single button press
• keyboard keys: assign traditional keyboard keys; by applying modifier keys and layout switching, you might even try for fitting a whole keyboard into the 16 buttons
• additional input modes, not just DirectInput
• layout backup/restore: save your layouts to human-readable files and swap them in/out; manually edit and customize configurations, without the device in-hand; apply saved configurations for different applications with only a few clicks in the browser

We preserved the RP2040's through-hole connections and additional GPIO pads so that it can be easily integrated to larger projects or extended with additional components - add Hall sensors, potentiometers, joysticks, switches, etc.

As more of a component than a product, we intentionally omit casing the device - refer to the dimensions in listing pictures for everything you'd need to know in order to case it or skin the buttons. The V2 (having joysticks) also omits the joystick fingerpads,⁴ which it remains for the designer to customize, depending on the application or as suits.

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¹ Don't be thrown by the symbolic terminology (∆, □, and so on) in listing images; this is not "an XBox" or "a PS3" controller. That's just a common reference point. To a computer, these inputs are just HID controller signals: eg, in Windows, DirectInput codes 1-16. Easily reconfigurable for other input paradigms, like XInput and the like. See the listing documents for a translation matrix.

² Of course, it'll also interact with any software that recognizes PSP, XBox, and generic controllers out-of-the-box. Probably even works with a lot of devices that have USB ports for such controllers, but we make no guarantees (some gaming platforms have started adding authentication mechanisms to their controllers). You may have to make a few changes in the GP2040 web configuration interface, depending on your application.

³ Python, the C languages, Windows Driver frameworks, the sundry Javascript frameworks, PowerShell, Bash, etc. - all have simple, straight-forward ways of reading USB-HID controller ("gamepad") inputs.

⁴ Included separately/loose, to do with as you will, though we can't see what one would...