the wii nunchuk is one of the greatest microcontroller input devices to come along in some time. they are also quite hollow. i decided to put an atmeg and a xbee wireless chip inside the grip. with this, the micro can be reprogrammed wirelessly with the arduino ide, and controll a multitude of devices through a simple serial protocol. as a demo, i attached another xbee to an oled display. (4d systems) in the last 2 pictures, you can see a primative menu system, and a graph displaying the accelerometer outputs.
impressive, which xbee model are those?
i'm using the series 2 chips. (2mw) they work very well once they are programmed correctly. the x-ctu program from digi makes that simple enough. i haven't really gotten into the api mode, but most things can be done from the at command mode. set them to 19200 baud if you want to do the wireless reprogramming with arduino ide. don't use broadcast mode, as you will have no error correction. you may need to lower packetization timeout depending on your needs, and give 'em a second to initialize before you start sending data.
Good evening,
Would it be possible to have details of this assembly?
well, it has been some time since i made this. it was one of my favorites though, being my first real use of most of these components. the display is a micro-oled from 4d systems. (great display) it is driven by a simple serial command set. the serial lines are tied to the xbee serial lines. both are powered by a small li-po battery under the xbee.
inside the nunchuk is an atmega168 on perfboard with an external resonator, led, and a couple caps. the serial line from the mcu is connected to the xbee over which it sends the commands directly to the display. the nunchuk pcb is connected to mcu over a twi interface, and all is powered by another small li-po.
if i did it again, i would use something like this:
http://www.dealextreme.com/details.dx/sku.14387
that would save the considerable cost of the xbee modules, and could presumably be interfaced in the same way as the original 'chuck.
Thank you for the quick reply.
In fact I have a wireless nunchuck, but I wanted to increase the range by using the module Xbee.
neat! some of the new modules do have incredible range. here is some good looking code to interpret the twi data:
http://todbot.com/arduino/sketches/NunchuckPrint/NunchuckPrint.pde
i think i used some functions from that.
I look at it and if I can modify my wireless nunchuck I talk about on this post.
What I need is to know what and where to measure in the nunchuck.
i guess the approach will depend on your intended use. i envisioned a microcontroller and xbee attached to the nunchuck receiver interpreting the twi data, converting it to ttl serial, and relaying it over the longer xbee link to whatever you are controlling.
inside that nunchuck is likely a mcu reading the sensors, and sending data on a proprietary 2.4ghz format to the receiver where it is then converted into the easy to read twi protocol read by the wiimote.(or atmega)
i hope that makes some sense. 
Thank you for these details.
This one is lovely, and certainly something I will put on my project list. (Why does that list always grow bigger?)
I am new to xbee, I thought you needed a shield for the arduino to use these, can I make a wireless nunchuck without the shield, only using a mini pro and the antenna? what do I need inbetween?
Joachim
you only need a shield if you're afraid to solder. and if you are, you better get over it. the problem is the pin spacing on the xbee chips. they are spaced at 2mm rather than the more common .1 inches used on the arduino mini and most protoboard. the best thing to do is make your own pcb. you may even be able to get away with some point to point soldering. you really only need connect the tx/rx lines, power, and ground. at the time i actually used a manufactured board i had on hand to break out the xbee pins to standard .1 inch spacing. (cut and re-routed some traces) i think i got it from sparkfun. keep in mind, that if you use series 2 modules, you will need a serial link to your computer to program it. a ftdi cable works. read some data sheets. they can be a little tough, but when you know what to look for, you can breeze through them.
hello... 
I was wondering if you can help me to figure out the meaning of one of the bus pins in my wireless nunchuck resiver
I have this
vcc
gnd
data
clk
wcs :o ????????????????? can be wireles control sistem???????? I don`t know
can you help me guys please 
because I try to conect the wireless resiver into the arduino and not conect that pin because I don`t know what it is
and maybe that is the reason because do it not work 
thanks
It looks like this configuration could help me achieve a goal I have with regards to utilizing the nunchuk C/Z buttons to activate the Wii Remote's A/B buttons wirelessly.
I'm looking to do a modification that would enable this to happen to enhance game play, not to control other devices.
My plan would be to solder wires directly to the A/B buttons on the Wii remote and have them attached to a receiver. The receiver would receive input from the nunchuk when the C/Z buttons are pressed and activate those controls during game play.
Has the application of this configuration been considered? Any advice would be helpful. Thank you!
Is there anyone who has further technical knowledge of the