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

Step 3Programming

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
//--------------------------------------------------------------------
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9 comments
May 7, 2012. 7:49 AMbiomech75 says:
Fix the code !!! and post it
May 10, 2012. 2:54 PMcaptainrwooten says:
If you are using Arduino 1.0 IDE you will have to change some commands. The error codes will tell you which ones. Also the code doesn't specify some registers, you'll have to plug those in yourself. Good luck.
Jul 10, 2010. 11:59 PMjac.diamond says:
Is the code posted alright? Im thinking of doing this but i dont want to buy the stuff until i know its alright.
Aug 18, 2010. 5:08 AMcarlosanchez says:
I found the original code Here you go! http://oomlout.com/tmp/SERB_WiiNunChuckControl.txt
Jul 27, 2011. 12:16 PMdoby162 says:
This is an awesome guide!! Thanks oomlout and also thanks to carlosanchez for providing the uncorupted code :P I will definantly link to this in the instructable I make with my nunchuck :D
Nov 28, 2009. 6:27 PMAsuraku says:
 This code is an absolute mess and I can't seem to figure out how to fix it. Could someone post an un-scrambled working copy?
Aug 18, 2010. 5:08 AMcarlosanchez says:
http://oomlout.com/tmp/SERB_WiiNunChuckControl.txt
Jan 13, 2010. 6:59 PMMdob says:
Agreed, code is screwed; lets hope that Oomlout fixes it soon.
Aug 18, 2010. 5:09 AMcarlosanchez says:
http://oomlout.com/tmp/SERB_WiiNunChuckControl.txt
Jun 9, 2009. 8:27 PMZeusFury says:
i think i am missing _SERB_WiiNunchuckControl.hex because i got this error ....FR0N58YFUI0OXF5\_SERB_WiiNunchuckControl\applet\_SERB_WiiNunchuckControl.hex': No such file...FR0N58YFUI0OXF5\_SERB_WiiNunchuckControl\applet/_SERB_WiiNunchuckControl.cpp:133: undefined reference to `beginSerial'... i would really like some help on this pleas
Jun 8, 2009. 4:24 PMfred_thedog says:
I get the same error as TXTCLA55. Haven't spent any time trying to find the problem yet though.
May 30, 2009. 9:17 PMZeusFury says:
avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

i got these errors can some 1 help
May 9, 2009. 10:43 AMTXTCLA55 says:
Errpr code: arduino cannot determine program size, says it cannot find the files needed
May 10, 2009. 6:15 PMTXTCLA55 says:
nope same error. I tried deleting the stuff at the end ( labled "delete if not using") and I still got error codes. I'll try sending a email to the one you suggested.

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Author:oomlout