Hacking a Wii Nun-Chuck Controller (wired and wireless) to control your Robot - Pt 1

Why would I want to use a Nunchuck to control my robot?

Why not :)

Besides the low cost (a wireless nunchuck I purchased only cost me $5 brand new, and it came with 2xAAA rechargable energizer batteries, worth $4 in themselves!.


Besides cost, its the innards that got my attention. For that small price, you get an Analogue control stick, 2 buttons and the best part, a three-axis accelerometer for motion-sensing and tilting. And if you buy a wireless one, you also get a 2.4gig receiver with it. Alongside all that, Communications are bidirectional synchronous serial I2C meaning you can communicate with it and also send commands to it while receiving them.


So... if you buy the cheapest, or one of the cheapest arduino sticks, these can be easily hooked up into them. So for under $20 you could have the entire solution bundled up and built within about an hour or two, less even.


The pictures below show my current progress. Before attempting to tackle anything regarding actually using the nunchuck as a control device, I need to find out all the serial information that it is sending so I can then use that in my quest. How each control will be implemented I have not decided as yet, but it is definitely on the right track.


Picture 1.
Shows the mess of experimentation and the lack of an expansion board.
The idea here was basically to retrieve the information from the chuck without the need for a serial monitor, but simply an LCD screen. The numbers are indicated in the first picture.


Please take note, the analogue X,Y is not calibrated! it should be 128/128- and this is a $50 official Nintendo Wii chuck. Keep that in mind when you see the $4 wireless calibration.


http://www.devogeninteractive.com/pi...7_51F242C1&jpg


The figures are denoted in the picture. I have the Wii lying sideways so of course the accelerometer is showing odd readings. So mission success! I will document the process as best I can if anyone else wants to have a go.


Parts you will require:

• Wii nunchuck
• Arduino processor, just about any type I am using an cheap clone, which is a freetronics eleven board, which has some nice features and was about $25. NOTE ARDUINO MEGA USERS - you have dedicated I2C ports, so you cant use analogue ports 4 and 5. Use.. 20/21 i think.
• 4 x small wires if you are soldering, 4 breadboard jumpers if you are not or dont want to damage your nunchuck. This can all be done externally and does not require opening the nunchuck (unless you like getting your hands dirty :I )
• Latest version of Arduino, which can be found here: http://arduino.cc/en/Main/Software

• The nunchuck C library (github) https://github.com/todbot/wiichuck_adapter

OPTIONAL


This is a handy thing I saw, I dont have one but it can save you the wires (not that 4 wires is a big deal really..)

http://www.devogeninteractive.com/pi...D_51F245B3&jpg


These are available for sale at http://store.fungizmos.com/items/212 for about $4


Onward with the construction...

• If you look down the barrel of your nunchuck remote, you will see 6 pins. They are as follows.

http://www.devogeninteractive.com/pi...9_51F24475&jpg



There is really 4 wires you need to worry about. And do not pay attention to colours!!


Wii adapters will use different colour wires, so you want to use the plug as your guide.


1. GND goes to GND on your Arduino, any ground.
2. 3.3v goes to the 5v+Vin on your arduino
3. SDA goes to Analogue pin 4
4. SCL goes to Analogue pin 5


http://www.devogeninteractive.com/pi...B_51F24789&jpg








Quite simply connected, the breadboard jumpers will actually fit in the pin holes above the slots and you need not even solder for this testing. If its an old wii chuck, go for it, rip the end off and hard wire the sucker!


It's pretty straight forward


I learnt everything from this website, please go here for any additional help with the libraries:

http://todbot.com/blog/2008/02/18/wi...ter-available/

That's where I got started.




So, we have it hooked up, now what do we do? The code to access the chuck is very simply, all we need to do is initialise it. Of course make sure your port is selected in Arduino and your board is plugged in.


So for a simple starter program, try this. Go into Arduino, if you installed the library and it wont show, restart the program. Once you find it, go to Examples and load the nunchuck demo.


code should look as below:

Quote:

---

/* * ArduinoNunchukDemo.ino
*
* Copyright 2011-2013 Gabriel Bianconi, http://www.gabrielbianconi.com/
*
* Project URL: http://www.gabrielbianconi.com/projects/arduinonunchuk/
*
*/




#include <Wire.h>
#include <ArduinoNunchuk.h>




#define BAUDRATE 19200




ArduinoNunchuk nunchuk = ArduinoNunchuk();




void setup()
{
Serial.begin(BAUDRATE);
nunchuk.init();
}




void loop()
{
nunchuk.update();




Serial.print(nunchuk.analogX, DEC);
Serial.print(' ');
Serial.print(nunchuk.analogY, DEC);
Serial.print(' ');
Serial.print(nunchuk.accelX, DEC);
Serial.print(' ');
Serial.print(nunchuk.accelY, DEC);
Serial.print(' ');
Serial.print(nunchuk.accelZ, DEC);
Serial.print(' ');
Serial.print(nunchuk.zButton, DEC);
Serial.print(' ');
Serial.println(nunchuk.cButton, DEC);
}

---

Now, this is pretty easy to understand. As you can see all we are doing is accessing Gabs wonderful library and assigning the chucks output to the serial port. Now, I wanted to do this with the LCD shield (16x2) so I modified it simply to the following:

Quote:

---

#include <ArduinoNunchuk.h>


#include <Wire.h>
#include <LiquidCrystal.h>


ArduinoNunchuk nunchuk = ArduinoNunchuk();
LiquidCrystal lcd( 8, 9, 4, 5, 6, 7 );


void setup()
{
nunchuk.init();
lcd.begin(16, 2);


}


void loop()
{


nunchuk.update();
lcd.setCursor(0, 0);
lcd.print(nunchuk.analogX, DEC);
lcd.print(' ');
lcd.print(nunchuk.analogY, DEC);
lcd.print(' ');
lcd.print(nunchuk.zButton, DEC);
lcd.print(' ');
lcd.print(nunchuk.cButton, DEC);
lcd.setCursor(0, 2);
lcd.print(nunchuk.accelX, DEC);
lcd.print(' ');
lcd.print(nunchuk.accelY, DEC);
lcd.print(' ');
lcd.print(nunchuk.accelZ, DEC);
lcd.print(' ');
delay(150);
lcd.clear();
}

---

So basically the same thing, but instead of having to view the serial monitor I can check the screen to make sure it's working OK.

Now that we have our code to figure out the values for the nunchucks output, I worked at cleaning it up a bit.

I got my $4 brand new wireless nunchuck, ripped apart the receiver and hooked that up instead.

Now, I did need a Wii controller to plug the receiver into just to get the nunchuck to sync to the receiver - but the Wii controller had no batteries or was not actually connected to the wii, so it is obviously just a combinations of pins being accessed to trick the receiver into thinking there is a working wii controller plugged into it, but this is a very small issue, even if I can't figure out the combination I can wire a dummy loopback on the receiver and wire it in permanently, I will see.

Once again, take note of the X/Y calibration - perfect. Out of the box, not a degree off, as opposed to the official one that always will be slightly off. I don't know why, and I don't know how to calibrate them, all you can do is compensate for the miscalibration, in the case of the wired chuck in the first picture I would just start my RCS translation at a 0,0 of 121/128 and calculate from then on, with the wireless chuck no need for anything the things well balance and the accelerometer works very very well.

http://www.devogeninteractive.com/pi...3_51F24CC5&jpg

So as you can see, alot neater http://forum.kerbalspaceprogram.com/...s/k_smiley.gif the shield allows me to share I/O pins on the arduino and remove the need for an ugly breadboard.

Technically we don't need a driver as we are dealing with direct serial communication, so really all I am looking for is the figures the nunchuck throws back and then utilising them in some clever way to control my robots remotely.

Anyway.. That concludes Part 1.. in Part 2 I will be hooking this up to my Hexapod and we will start programming the pod to take commands from the chuck,