Converting a Wii Nunchuk Into a Standalone Wireless Joystick

Giliam de Carpentier has always liked the physical design of the Nintendo Wii Nunchuk, but the fact that it normally needs to be plugged into a Wii Remote limits its usefulness. Fortunately, these devices are easy to take apart, and after using “a Dremel to remove basically everything that wasn’t essential, leaving only the casing, a copperless PCB, the buttons and the potentiometers,” he had enough space to implement his own control scheme.

For de Carpentier's hack, the original joystick, buttons, and potentiometers were salvaged, but the rest of the joystick’s electronics are new — a BLE 4.2 module handles communication, while an ATtiny44A microcontroller translates button/stick movements into usable data.

Power is provided by a 300mAh LiPo and a TP4056 battery charger IC. The unit, however, is optimized for battery life, consuming less than 0.2 µA when idle and less than 6 mA when in use, so the need to actually charge it should be quite rare.

The modded Nunchuk interfaces with a PC as a joystick using a program called vJoy, along with custom Windows 10 application that takes care of the actual connection. More details, including ATtiny44A code and Eagle PCB files, are available in de Carpentier's project post if you’d like to recreate this build yourself.