Wii Nunchuk

Overview
The Nunchuk (model number RVL-004) is a corded controller peripheral for the Nintendo Wii Remote. The device input consists of an analog stick, a trigger button labeled "Z", a button labeled "C", and a three axis accelerometer provided by STMicroelectronics (part# LIS3L02AL). Functionally similar clones are also available from various third party providers.

The Nunchuk measurements are 113 mm (4.45 in) x 38 mm (1.5 in) x 37 mm (1.48 in).

The Nunchuk communicates via I²C and can be used as an input in compatible devices such as Arduino.

Technical Information
The Nunchuk uses a proprietary connector. The cable itself contains 4 wires:

Information based on Nunchuk for Adruino Tutorial from WindMeadow Labs. Information verified through experimentation.

red - 3.3+V power white - ground green - data yellow - clock

The Arduino uses "fast" I²C. To communicate,a device must send a handshake to the device:

0x40 - Begin connection 0x00 - request data

Data is requested each time the device is polled with "0x00". Data is returned with 6 byte chunks.