#define USE_NEW_WAY_INIT 1 // use "The New Way" of initialization <http://wiibrew.org/wiki/Wiimote#The_New_Way>
#define WII_IDENT_LEN ((byte)6)
#define WII_TELEGRAM_LEN ((byte)6)
#define WII_NUNCHUCK_TWI_ADR ((byte)0x52)
#include <Wire.h>
#include <string.h>
#include <utility/twi.h>
#undef int
#include <stdio.h>
uint8_t outbuf[WII_TELEGRAM_LEN]; // array to store arduino output
int cnt = 0;
int ledPin = 13;

void setup() {
  // initialize the serial port:
  Serial.begin(9600);
  Wire.begin(); // initialize i2c
  #define TWI_FREQ_NUNCHUCK 400000L
  TWBR = ((CPU_FREQ / TWI_FREQ_NUNCHUCK) - 16) / 2;
  nunchuck_init(0); // send the initialization handshake
  byte i;
  if(readControllerIdent(outbuf) == 0){
    Serial.print("Ident=");
    for (i = 0; i < WII_TELEGRAM_LEN; i++){
      Serial.print(outbuf[i], HEX);
      Serial.print(' ');
    }
    Serial.println();
  }
  Serial.println("Finished setup");
}

void loop() {
  // print the analog readings, separated by a tab:
  Wire.requestFrom (WII_NUNCHUCK_TWI_ADR, WII_TELEGRAM_LEN); // request data from nunchuck
  for (cnt = 0; (cnt < WII_TELEGRAM_LEN) && Wire.available (); cnt++){
    outbuf[cnt] = nunchuk_decode_byte (Wire.receive ()); // receive byte as an integer
    digitalWrite (ledPin, HIGH); // sets the LED on
  }
  clearTwiInputBuffer();
  if (cnt >= WII_TELEGRAM_LEN){  // If we recieved the 6 bytes, then go print them
    print ();
  }
  send_zero (); // send the request for next bytes
  delay (20);
}

byte nunchuck_init (unsigned short timeout){
  byte rc = 1;
  #ifndef USE_NEW_WAY_INIT
    Wire.beginTransmission (WII_NUNCHUCK_TWI_ADR); // transmit to device 0x52
    Wire.send (0x40); // sends memory address
    Wire.send (0x00); // sends sent a zero.
    Wire.endTransmission (); // stop transmitting
  #else
    unsigned long time = millis();
    do{
      Wire.beginTransmission (WII_NUNCHUCK_TWI_ADR); // transmit to device 0x52
      Wire.send (0xF0); // sends memory address
      Wire.send (0x55); // sends data.
      if(Wire.endTransmission() == 0){ // stop transmitting
        Wire.beginTransmission (WII_NUNCHUCK_TWI_ADR); // transmit to device 0x52
        Wire.send (0xFB); // sends memory address
        Wire.send (0x00); // sends sent a zero.
        if(Wire.endTransmission () == 0){ // stop transmitting
          rc = 0;
        }
      }
    }
    while (rc != 0 && (!timeout || ((millis() - time) < timeout)));
  #endif
  return rc;
}

char nunchuk_decode_byte (char x){
  #ifndef USE_NEW_WAY_INIT
    x = (x ^ 0x17) + 0x17;
  #endif
  return x;
}

byte readControllerIdent(byte* pIdent){
  byte rc = 1;
  Wire.beginTransmission (WII_NUNCHUCK_TWI_ADR); // transmit to device 0x52
  Wire.send (0xFA); // sends memory address of ident in controller
  if(Wire.endTransmission () == 0){ // stop transmitting
    byte i;
    Wire.requestFrom (WII_NUNCHUCK_TWI_ADR, WII_TELEGRAM_LEN); // request data from nunchuck
    for (i = 0; (i < WII_TELEGRAM_LEN) && Wire.available (); i++){
      pIdent[i] = Wire.receive(); // receive byte as an integer
    }
    if(i == WII_TELEGRAM_LEN){
      rc = 0;
    }
  }
  return rc;
}

void clearTwiInputBuffer(void){
  while( Wire.available ())
  Wire.receive ();
}

void send_zero (){
  for(byte i = 0; i < 3; i++){
    Wire.beginTransmission (WII_NUNCHUCK_TWI_ADR); // transmit to device 0x52
    Wire.send (0x00); // sends one byte
    Wire.endTransmission (); // stop transmitting
  }
}

void print (){
  int joy_x_axis = outbuf[0];
  int joy_y_axis = outbuf[1];
  int accel_x_axis = outbuf[2];// * 2 * 2
  int accel_y_axis = outbuf[3];// * 2 * 2
  int accel_z_axis = outbuf[4];// * 2 * 2
  int z_button = 0;
  int c_button = 0;
  if ((outbuf[5] >> 0) & 1){ z_button = 1; }
  if ((outbuf[5] >> 1) & 1){ c_button = 1; }

  Serial.print ("x:");
  Serial.print (joy_x_axis, DEC);
  Serial.print ("\ty:");
  Serial.print (joy_y_axis, DEC);
  Serial.print ("\tX:");
  Serial.print (accel_x_axis, DEC);
  Serial.print ("\tY:");
  Serial.print (accel_y_axis, DEC);
  Serial.print ("\tZ:");
  Serial.print (accel_z_axis, DEC);
  Serial.print ("\tz:");
  Serial.print (z_button, DEC);
  Serial.print ("\tc:");
  Serial.print (c_button, DEC);
  Serial.print ("\r\n");
}