Use a completely unmodified wireless Wii Nunchuck as a control system for any Arduino based project. No added radio transmitter/receiver pairs etc.
This instructable does assume some experience with the Arduino microcontroller.
The radio receiver that comes with the wireless 'chuck is connected to an Arduino which then reads data from the 'chuck.
There are descriptions on the net of how to use an Arduino to "read" data from a standard wired Nunchuck. This is a handheld device which is meant to connect via a short cable to a socket in the base of a Wii controller (the rectangular thing), which then sends data via Bluetooth to the Wii (or indeed a PC).
A special adapter has been made by with six contacts on it to enable the experimenter to connect the plug on the end of a Nunchuck to the pins of an Arduino board.
Here is an example of one of these:
I am going to decribe a more robust connection however.
The software required to "read" a standard chuck (i.e. with a cable) will not work on a wireless chuck. The software for wired 'chucks can be found in several places on the net. The wireless 'chucks are not made by Nintendo and there are several makes out there - all from China.
The wireless chuck has a 3 axis accelerometer, 2 buttons and a proper proportional thumb operated joystick. The price is very low so this could be a great way to create a short range wireless control system for all sorts of Arduino based devices. This is why I am posting this instructable.
Here are two types of wireless chuck that I know will work with this hack. I haven't tried any others yet.
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Step 1: What the Wires Mean
It is easy to use a Nunchuck adapter to connect a wired or wireless chuck to an Arduino. However for a more stable connection I suggest:
Buy a Wii Nunchuck extender cable. This has a Nunchuck socket on one end and a plug on the other. Cut the cable so you now have the socket on one end and some free wires on the other which you can solder to your Arduino.
Step 2: How to Connect These Wires to Board
Once this socket is soldered to Arduino, you just plug radio receiver of wireless Nunchuck into it and off you go.
Only 4 of the 6 contacts in the plug/socket are required, these are:
+V Power (Chuck designed for 3.3V but seems to work well with a 5V supply from Arduino board)
SDA (connect to Analog pin 4 on Arduino)
SCK (connect to Analog Pin 5 on Arduino)
Check and recheck your wires and label them. Here is a view looking into the female socket (on the end of your extension cable that you have just cut in half) you will insert the male plug sticking out of the wireless nunchuck radio receiver unit into:
NOTE: I have updated this figure 25/6/10 as previous diagram was wrong! very very easy to make a mistake here.
Step 3: Wii Chuck Extension Cable
Here is a photo of the Wii Nunchuck extension cable I cut to make the socket-on-end of a lead:
Step 4: Wire Colours
If you buy the exact same make of extension lead I have shown in previous photo, and you cut it and bare the wire ends, these are the colours of the wires and the tabs on the arduino that you connect them to.
If you cut the socket from a different make of extension lead the colours may be different. In that case check and double check the wires against the diagram 2 pages previously using a meter set to measure resistance (one lead touches copper tag inside the socket and with the other lead check all the bared wire ends until resistance is zero Ohms....then you know which tag in the socket is which wire end).
Step 5: Connect Wires to Board
Some versions of the software will convert analog pins 2 and 3 into +5V and GND so you can line up the 4 pins, SCK, SDA, 5V and GND in a row.
I chose to solder +V and GND to the +5V and GND pins on the Arduino permanently.
SCK then goes to Analog pin 5 and SDA goes to Analog pin 4.
Also, and this has only been discovered recently by trial and error, to get this to work using this "cut Nunchuck extender cable" as the means of connection to the wireless chuck receiver - you have to solder in two external pull-up resistors - about 1800 Ohms each seems about right.
One goes between SCK(analog pin 5) and +5V and the other goes between SDA(analog pin 4) and +5V.
Apparently these aren't required if you keep the receiver right next to the Arduino (i.e. by using an Arduino adapter of the TodBot type).
Step 6: Wiring to Arduino 2
Here is an image of the wiring of my own Arduino. Here I am using the wireless chuck to steer my self-balancing skateboard (i.e. a form of self-balancing robot).
Step 7: The Software
My software has been modified from the general purpose wireless chuck reader software developed by others. It is based on code by Chad Phillips, Mike Dreher, Björn Giesler and more tidying work recently by Mike Dreher (see forum link below).
APRIL 2011: I have now added my version as a text file to this instructable page.
This topic has been on an Arduino forum and the problem has recently been solved.
There are two versions of the software, both of which I have managed to get working:
This Arduino forum page contains both versions of the code:
I can confirm this works on the latest Arduino boards with the ATmega328 processor, using Arduino17 to compile and load it.
Also see this wireless chuck controlled R2D2 robot(!):
More on my self balancing skateboards here:
Here is a video showing the wireless chuck controlling the steering of my 2 wheeled self balancing skateboard.
Clearly this hack could be used to control all sorts of robots, cars, servo operated devices, robot arms, airborne mouse etc. and is a very cheap to do. You can use the joystick or just tilt the chuck in the direction you want your device to move.