Control Your Robot Using a Wii Nunchuck (and an Arduino)

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Control Your Robot Using a Wii Nunchuck (and an Arduino)

After wearing myself out playing Wii Boxing I got to thinking wouldn't it be great if I could use this to control my robot, (looking to my left hand).

Looking around the internet I found a bevy of people doing similar things, (links to everyone just below the video). So what follows is a re-packaging of all their hard work, resulting in a robot controllable by both the Wii nunchuck's joystick or more interestingly its accelerometers.

A quick video of my Arduino Controlled Servo Robot - (SERB) being controlled by a Wii nunchuck.

(resources)

(here) - Arduino Code - Chad at WindMeadows.com has written excellent arduino code for reading the Wii nunchuck. Code which I have included pretty much verbatim in this project. if you're interested in more technical details this is where to look.
(here) - Nunchuck Details - WiiLi.org has a great wiki about all things Wii, this is a link to a page that describes the nunchucks protocol and how to calibrate your nunchuck.
(here) - WiiChuck Adapter - Tod of todbot.com very kindly produced a small adapter to make plugging your nunchuck into a breadboard particularly easy.

(similar projects)

(here) - Wireless Nunchuck Control - Frank over at Society of Robots went one step further adding a wireless link so he can control his Arduino robot with all the tilt and twist fun from afar.
(here) - Nunchuck Controlled Pan and Tilt Camera - Using a Nunchuck and an Arduino to control the pan and tilt of a camera.
(here) - Nunchuck and Arduino Controlled Canoe - Finally a rather epic project that uses an Arduino, nunchuck, servos and small trolling motor to drive a Canoe.

(if you have an Arduino nunchuck project you've completed drop me a line and it can be added here)
(shameless plug)
To check out more of our lovely open source projects - oomlout.com

Parts & Tools

Only a few parts to collect before we get wiring and programming

Robot - (Arduino Controlled Servo Robot - (SERB) )
( build your own , or purchase a lovely kit ($175)

We use an Arduino Controlled Servo Robot - (SERB) however any Arduino powered dual servo robot will work. Other options (here)

Electronics - ($24)

Wii Nunchuck - ($20) - (Amazon) , or at your closest Blockbuster or CircuitCity
WiiChuck Adapter - ($4) - A small circuit board that allows you to plug your nunchuck into a breadboard without modifying it. (if you don't want to use your nunchuck on your Wii you can save yourself four dollars and simply cut the connector off and plug the wires directly into your breadboard) - (FunGizmos)
Assorted pieces of Breadboard wire - (22 AWG solid)

That's it onto Wiring it up

Wiring

Wiring this up could not be simpler, and requires only four wires.

Explained

Data - (d) - (green) - Arduino Analog 4
Clock - (c) - (yellow) - Arduino Analog 5
Ground - (-) - (white) - Arduino gnd
+3.3v - (+) - (red) - Arduino 5v (although the Arduino is a 3.3 volt device it seems to work without adverse effects at 5 volts)

Pictorially

refer to the attached wiring diagram (05-(NUSE)-Wiring Diagram.pdf)

Downloads

05-(NUSE)-Wiring Diagram.pdf

Programming

The Wii Nunchuck is now connected to the Arduino's i2c port. For those of you (including myself) who don't really understand what that means do not fret, just rest assured, it is a good thing. If you would like to know more of the nitty gritty details they can be found (here)

(many thanks to chad at windmeadow.com for doing the research and writing really easily understood Arduino code to interact with the Wii nunchuck, the program below includes his code virtually unchanged).

What it does

The program will default to using the nunchucks joystick for control. If you push the stick forward your robot will go forward, reverse, backwards and so on.
If you hold down the "Z" button (the big one on the front). Your robot will now move based on the tilt of the nunchuck. Tilt forward to go forward...
Finally if it isn't quite working the program will send the state of the nunchucks buttons, joystick and accelerometers, every second over the Arduino's USB port. (just open the debug window at 9600 to see this data)

For those interested in simply getting it going.

Copy and Pasting

Copy the Arduino code from below
Paste it into the Arduino development environment.
upload and start playing

Using the Code in Your Own Program

First initialize the nunchuck by calling nunchuck_init ();
Next every time you wish to update the values of the nunchuck in your sketch call readNunchuck();
Next to directly access the values call getNunValue(Variable Constant); (ex. YAXIS)
Finally if you wish to use the accelerometer but have it scaled to a number of Gs (ie. 1 g = 1 force of gravity). you can call getXGs();, getYGs(); or getZGs();

Appendix 1 - _SERB_WiiNunchuckControl.pde


//START OF NUNCHUCK PREAMBLE - For more in depth information please visit the original source of this code http://www.windmeadow.com/node/42 
//-------------------------------------------------
/*
 * Wiring Details
 * white  - ground
 * red    - 3.3+v  - 5 volts seems to work
 * green  - data   - Analog 4
 * yellow - clock  - Analog 5
 */

#include  #include   #undef int #include   uint8_t outbuf[6];		// array to store arduino output int cnt = 0;                    // counter used for nunchuck comunication int ledPin = 13;  int nunchuckValues[] = {0,0,0,0,0,0,0,0,0,0}; //An array to store the nuncheck values  /*  * The index of each value within the nunchuckValues[] array  * ie. XSTICK value is stored at nunchuckValues[XSTICK] (0)  */ #define XSTICK 0      //The joystick values      #define YSTICK 1 #define XAXIS 2       //The three accelerometer values      #define YAXIS 3         #define ZAXIS 4  #define ZBUTTON 5     //Front button values  (0 when pressed)   #define CBUTTON 6   #define XAXISDELTA 7  //Change in accelerometer data from last read; #define YAXISDELTA 8    #define ZAXISDELTA 9   //Nunchuck G calculating Constants /*  * For scaling the raw values from the nunchuck into G values  * Details on callibration and the maths can be found at  *    http://www.wiili.org/index.php/Motion_analysis  (Copied from http://www.wiili.org/index.php/Motion_analysis)      Zero Points         $x_0 = (x_1 + x_2) / 2\,$          $y_0 = (y_1 + y_3) / 2\,$          $z_0 = (z_2 + z_3) / 2\,$       One G points         $x = \frac{x_{raw} - x_0}{x_3 - x_0}$          $y = \frac{y_{raw} - y_0}{y_2 - y_0}$          $z = \frac{z_{raw} - z_0}{z_1 - z_0}$  */  /* Not all of these are used and could be deleted (kept to make interpretting math's  * Easier 0-Zero G Value 1-Value when laying on table 2-Value when resting on nose  * 3-Value when resting on side (left side up) */ #define X0 500  #define X1 500 #define X2 500 #define X3 711  #define Y0 465 #define Y1 481 #define Y2 621 #define Y3 449  #define Z0 578 #define Z1 785 #define Z2 575 #define Z3 582  //END OF NUNCHUCK PREAMBLE - For more in depth information please visit the original source of this code http://www.windmeadow.com/node/42  //------------------------------------------------------  //-------------------------------------------------------------------------- // START OF ARDUINO CONTROLLED SERVO ROBOT (SERB) PREAMBLE #include   #define LEFTSERVOPIN  10   #define RIGHTSERVOPIN  9  #define MAXSPEED 10  //due to the way continuous rotation servos work maximum speed is reached at a much lower value than 90 (this value will change depending on your servos) (for Parallax servos)  Servo leftServo;  Servo rightServo;   int leftSpeed = 100;  //sets the speed of the robot (left servos)                        //a percentage between -MAXSPEED and MAXSPEED int rightSpeed = 100;  //sets the speed of the robot (both servos)                        //a percentage between -MAXSPEED and MAXSPEED int speed = 100;      //used for simple control (goForward, goBackward, goLeft, and goRight                       //a percentage between 0 and MAXSPEED   // END OF ARDUINO CONTROLLED SERVO ROBOT (SERB) PREAMBLE //--------------------------------------------------------------------------  long lastPrint; //a long variable to store the time the wiimote state was last printed #define PRINTINTERVAL 1000  //the number of milliseconds between outputting the nunchuck state over the usb port #define DEADBAND 20         //A percentage away from center that is interpretted as still being zero   void setup(){   Serial.begin(9600);   //Starts the serial port (used for debuging however makes servos jumpy)   nunchuck_init ();     // send the nunchuck initilization handshake   serbSetup();         // adds the servos and prepares all SERB related variables   lastPrint = millis(); }   void loop(){   readNunchuck();       //Reads the current state of the nunchucks buttons and accelerometers   if(!getNunValue(ZBUTTON)){     moveWiiAcelerometer();            //moves the wii deoending on the nunchucks acceleration values    }else{     moveWiiJoystick();   }   if((millis() - lastPrint) > PRINTINTERVAL){  //If a second has passed since last printing nunchuck values print them     printData();          //print nunchuck values     Serial.println();     //add an enter     lastPrint = millis(); //store current time as lastPrint   }  }  void moveWiiAcelerometer(){  moveDifferential(getYGs() * (float)100,getXGs()*(float)100);  }  void moveWiiJoystick(){  moveDifferential(map(getNunValue(YSTICK),30,220,-100,100),map(getNunValue(XSTICK),30,220,-100,100));  }  //Takes in a speed and a direction input (like a joystick) and translates it to speed commands  void moveDifferential(int speed1, int direction1){   speed1 = deadBandFilter(speed1);   direction1 = deadBandFilter(direction1);   setSpeedLeft(speed1 + direction1);   setSpeedRight(speed1 - direction1); }  int deadBandFilter(int value){  if(value > -DEADBAND && value < DEADBAND){value = 0;}  else{    if(value > 0){value = value - DEADBAND * 100 / (100-DEADBAND);}    else{value = value + DEADBAND * 100 / (100-DEADBAND);}  }  return value;  }   //START OF NUNCHUCK ROUTINES //-------------------------------------------------------------------------------------------------------   //Calculates and returns the xAxis acceleration in Gs float getXGs(){   return ((float)getNunValue(XAXIS) - X0) / (X3 - X0); }  //Calculates and returns the yAxis acceleration in Gs float getYGs(){   return ((float)getNunValue(YAXIS) - Y0) / (Y2 - Y0); }  //Calculates and returns the zAxis acceleration in Gs float getZGs(){   return ((float)getNunValue(YAXIS) - Z0) / (Z1 - Z0);   }  //START OF NUNCHUCK Reading CODE - For more in depth information please visit the original source  //of this code http://www.windmeadow.com/node/42  //--------------------------------------------------------------- void readNunchuck(){   Wire.requestFrom (0x52, 6);	// request data from nunchuck   while (Wire.available ()) {       outbuf[cnt] = nunchuk_decode_byte (Wire.receive ());	// receive byte as an integer       digitalWrite (ledPin, HIGH);	// sets the LED on       cnt++;     }    // If we recieved the 6 bytes, then go print them   if (cnt >= 5) {         nunchuckValues[XSTICK] = outbuf[0];         nunchuckValues[YSTICK] = outbuf[1];         int tempNun_xAxis = outbuf[2] * 2 * 2;          int tempNun_yAxis = outbuf[3] * 2 * 2;           int tempNun_zAxis = outbuf[4] * 2 * 2;         nunchuckValues[ZBUTTON] = 0;
        nunchuckValues[CBUTTON] = 0;

         // byte outbuf[5] contains bits for z and c buttons
         // it also contains the least significant bits for the accelerometer data
         // so we have to check each bit of byte outbuf[5]
        if ((outbuf[5] >> 0) & 1) { nunchuckValues[ZBUTTON] = 1; } //checking if Z button is pressed (0=pressed 1=unpressed)
        if ((outbuf[5] >> 1) & 1) { nunchuckValues[CBUTTON] = 1; } //checking if C button is pressed (0=pressed 1=unpressed)
        if ((outbuf[5] >> 2) & 1) { tempNun_xAxis += 2; } //adding second least significant bit to x_axis
        if ((outbuf[5] >> 3) & 1) { tempNun_xAxis += 1; } //adding least significant bit to x_axis
        if ((outbuf[5] >> 4) & 1) { tempNun_yAxis += 2; } //adding second least significant bit to y_axis
        if ((outbuf[5] >> 5) & 1) { tempNun_yAxis += 1; } //adding least significant bit to x_axis
        if ((outbuf[5] >> 6) & 1) { tempNun_zAxis += 2; } //adding second least significant bit to z_axis
        if ((outbuf[5] >> 7) & 1) { tempNun_zAxis += 1; } ////adding least significant bit to x_axis

        nunchuckValues[XAXISDELTA] = tempNun_xAxis - nunchuckValues[XAXIS];
        nunchuckValues[XAXIS] = tempNun_xAxis;
        nunchuckValues[YAXISDELTA] = tempNun_yAxis - nunchuckValues[YAXIS];
        nunchuckValues[YAXIS] = tempNun_yAxis;
        nunchuckValues[ZAXISDELTA] = tempNun_zAxis - nunchuckValues[ZAXIS];
        nunchuckValues[ZAXIS] = tempNun_zAxis;
    }
  cnt = 0;
  send_zero (); // send the request for next bytes
}

int getNunValue(int valueIndex){
  return nunchuckValues[valueIndex];
}

void nunchuck_init (){
  Wire.begin ();		// join i2c bus with address 0x52
  Wire.beginTransmission (0x52);	// transmit to device 0x52
  Wire.send (0x40);		// sends memory address
  Wire.send (0x00);		// sends sent a zero.  
  Wire.endTransmission ();	// stop transmitting
}

void send_zero () {
  Wire.beginTransmission (0x52);	// transmit to device 0x52
  Wire.send (0x00);		// sends one byte
  Wire.endTransmission ();	// stop transmitting
}

// Encode data to format that most wiimote drivers except
// only needed if you use one of the regular wiimote drivers
char nunchuk_decode_byte (char x)  {
  x = (x ^ 0x17) + 0x17;
  return x;
}

//END OF NUNCHUCK CODE - For more in depth information please visit the 
//original source of this code http://www.windmeadow.com/node/42 
//---------------------------------------------------------------

//------------------------------------------------------------------------
//START OF ARDUINO CONTROLLED SERVO ROBOT (SERB) ROUTINES

/*
 * sets up your arduino to address your SERB using the included routines
*/
void serbSetup(){
  setSpeed(speed);
  pinMode(LEFTSERVOPIN, OUTPUT);     //sets the left servo signal pin 
                                     //to output
  pinMode(RIGHTSERVOPIN, OUTPUT);    //sets the right servo signal pin 
                                     //to output
  leftServo.attach(LEFTSERVOPIN);    //attaches left servo
  rightServo.attach(RIGHTSERVOPIN);  //attaches right servo
  goStop();
}


/*
 * sets the speed of the robot between 0-(stopped) and 100-(full speed)
 * NOTE: speed will not change the current speed you must change speed 
 * then call one of the go methods before changes occur.
*/ 
void setSpeed(int newSpeed){
  if(newSpeed >= 100) {newSpeed = 100;}     //if speed is greater than 100 
                                            //make it 100
  if(newSpeed <= 0) {newSpeed = 0;}         //if speed is less than 0 make 
                                            //it 0 
  speed = newSpeed * MAXSPEED / 100;        //scales the speed to be 
                                            //between 0 and MAXSPEED
}

/*
 * sets the speed of the robots rightServo between -100-(reversed) and 100-(forward)
 * NOTE: calls to this routine will take effect imediatly
*/ 
void setSpeedRight(int newSpeed){
  if(newSpeed >= 100) {newSpeed = 100;}     //if speed is greater than 100 
                                            //make it 100
  if(newSpeed <= -100) {newSpeed = -100;}   //if speed is less than -100 make 
                                            //it -100 
  rightSpeed = newSpeed * MAXSPEED / 100;   //scales the speed to be 
                                            //between -MAXSPEED and MAXSPEED
  rightServo.write(90 - rightSpeed);             //sends the new value to the servo
}

/*
 * sets the speed of the robots leftServo between -100-(reversed) and 100-(forward)
 * NOTE: calls to this routine will take effect imediatly
*/ 
void setSpeedLeft(int newSpeed){
  if(newSpeed >= 100) {newSpeed = 100;}     //if speed is greater than 100 
                                            //make it 100
  if(newSpeed <= -100) {newSpeed = -100;}   //if speed is less than -100 make 
                                            //it -100 
  leftSpeed = newSpeed * MAXSPEED / 100;   //scales the speed to be 
                                            //between -MAXSPEED and MAXSPEED
  leftServo.write(90 + leftSpeed);               //sends the new value to the servo
}

/*
 * sends the robot forwards
 */
void goForward(){
 leftServo.write(90 + speed);
 rightServo.write(90 - speed);
}

/*
 * sends the robot backwards
 */
void goBackward(){
 leftServo.write(90 - speed);
 rightServo.write(90 + speed);
}
  
/*
 * sends the robot right
 */
void goRight(){
 leftServo.write(90 + speed);
 rightServo.write(90 + speed);
}

/*
 * sends the robot left
 */
void goLeft(){
 leftServo.write(90 - speed);
 rightServo.write(90 - speed);
}

/*
 * stops the robot
 */
void goStop(){
 leftServo.write(90);
 rightServo.write(90);
} 
//END OF ARDUINO CONTROLLED SERVO ROBOT (SERB) ROUTINES
//---------------------------------------------------------------------------


//START  OF PRINT ROUTINES (can delete if not using)
//---------------------------------------------------------------

//Prints the Nunchucks last read data (must call NUN_readNunchuck(); before calling
void printData(){
  Serial.print("XJoy= ");Serial.print (getNunValue(XSTICK), DEC); Serial.print ("\t");
  Serial.print("YJoy= ");Serial.print (getNunValue(YSTICK), DEC); Serial.print ("\t");
  Serial.print("XGs= ");Serial.print (getXGs() * 1000, DEC);  Serial.print ("\t");
  Serial.print("YGs= ");Serial.print (getYGs() * 1000, DEC);  Serial.print ("\t");
  Serial.print("ZGs= ");Serial.print (getZGs() * 1000, DEC);  Serial.print ("\t");
  Serial.print("ZBut= ");Serial.print (getNunValue(ZBUTTON), DEC);  Serial.print ("\t");
  Serial.print("YBut= ");Serial.print (getNunValue(CBUTTON), DEC);  Serial.print ("\t");
}

//END OF PRINT ROUTINES
//--------------------------------------------------------------------

Finished

I hope you've gotten it working and are having fun tilting and driving.

If its not quite working leave a message or send us an e-mail at help@oomlout.com and we'll try our best to help you get it working.

(shameless plug)
For more fun open source projects try visiting us at oomlout.com

Control Your Robot Using a Wii Nunchuck (and an Arduino)