The Wii Nunchuk is designed to work together with the Wii Remote on the Wii console. Contoured to fit perfectly in your hand, the Nunchuk adds extra buttons, an analog joystick, and additional motion-sensing control to expand the game play possibilities.
And it Uses the I2C 2-Wire Data Protocol ................
Open the Nunchuk case with a small screw-driver (1,5mm) as shown in the Video.
You should now have the Wii Nunchuk's Circuit Board as pictured above.
Now de-solder the 1,8k pull-up-resistors R1 and R2. No fear of SMD. SMDs sticks to the soldering iron!
Now solder the new pullup resistors. The Lego reference design suggests 82kohm pullup resistors for i2c. I found out, that 33kohm is the best value for stable connection. I changed the SMD resistors, but if you have no SMS resistors use common 1/4W size and solder the resistors on the connection cables. Additionally I mounted a drop-voltage-diode to reduce the voltage of the nunchuk.
Now cut the original Nunchuk cable connector of and strip the white insulation back by about 10mm to expose the conductors. Carefully spread them out in the correct order matching the circuit diagram order. Now using an original Lego Mindstorms NXT Black Connector Cable as a reference, slide the ordered coloured wires into the NXT Compatible Male Plug.
Carefully place the NXT Compatible Male Plug on a solid surface and take a small "Blade" Screw Driver and individually push the 6 Brass pins in the plug home. Next test that the new plug fits easily into the NXT's Sensor Sockets.
To finish the plug and make it secure. Get some 5 Minute Araldite and fill the back of the plug where the cable enters. Leave to dry for an hour, before carefully reassembling your Wii Nunchuk
Video of My NXT-Nunchuk Controlled Zammor Bot in Action!
Visit the Forums at forums.nxtasy.org for Code to start using your new NXT-Nunchuck Sensor...............