The Joystick Serial Code that Outputs the Proper Packet Format

joystick_serial_packet_assembly.ino

/*

   MATH

   Raw Values

  int joy_x_axis = nunchuck_buf[0];
  int joy_y_axis = nunchuck_buf[1];


   Without 255 Inversion

  int joy_x_axis = abs(2.55 * (nunchuck_buf[0]) - 331.5);
  int joy_y_axis = abs(2.55 * (nunchuck_buf[1]) - 331.5);


  With 255 Inversion

  int joy_x_axis = 255 - (abs(2.55 * (nunchuck_buf[0]) - 331.5));
  int joy_y_axis = 255 - (abs(2.55 * (nunchuck_buf[1]) - 331.5));

*/

#include <Wire.h>
#include <math.h>

static uint8_t nunchuck_buf[6];   // array to store nunchuck data,
static uint8_t nunchuck_data[4];

float a = 0;
float b = 0;
float angle = 0;
int allowSerialWrite = 0;

void setup() {
  Serial.begin(38400);

  nunchuck_setpowerpins(); // use analog pins 2&3 as fake gnd & pwr
  nunchuck_init(); // send the initilization handshake
}

void loop() {
  nunchuck_get_data();

  // map nunchuk data to a servo data point
  int x_axis = map(nunchuck_buf[0], 23, 222, 180, 0);
  int y_axis = map(nunchuck_buf[1], 32, 231, 0, 180);

  nunchuck_print_data();

}

static void nunchuck_setpowerpins() {
#define pwrpin PORTC3
#define gndpin PORTC2
  DDRC |= _BV(pwrpin) | _BV(gndpin);
  PORTC &= ~ _BV(gndpin);
  PORTC |=  _BV(pwrpin);
  delay(100);  // wait for things to stabilize
}

// initialize the I2C system, join the I2C bus,
// and tell the nunchuck we're talking to it
void nunchuck_init() {
  Wire.begin();                      // join i2c bus as master
  Wire.beginTransmission(0x52);     // transmit to device 0x52
  Wire.write(0x40);            // sends memory address
  Wire.write(0x00);            // sends sent a zero.
  Wire.endTransmission();     // stop transmitting
}

// Send a request for data to the nunchuck
// was "send_zero()"
void nunchuck_send_request() {
  Wire.beginTransmission(0x52);     // transmit to device 0x52
  Wire.write(0x00);            // sends one byte
  Wire.endTransmission();     // stop transmitting
}

// Receive data back from the nunchuck,
int nunchuck_get_data() {
  int cnt = 0;
  Wire.requestFrom (0x52, 6);     // request data from nunchuck
  while (Wire.available ()) {
    // receive byte as an integer
    nunchuck_buf[cnt] = nunchuk_decode_byte(Wire.read());
    cnt++;
  }
  nunchuck_send_request();  // send request for next data payload
  // If we recieved the 6 bytes, then go print them
  if (cnt >= 5) {
    return 1;   // success
  }
  return 0; //failure
}

// Print the input data we have recieved
// accel data is 10 bits long
// so we read 8 bits, then we have to add
// on the last 2 bits.  That is why I
// multiply them by 2 * 2

void nunchuck_print_data() {
  
  int accel_x_axis = nunchuck_buf[2]; // * 2 * 2; 
  int accel_y_axis = nunchuck_buf[3]; // * 2 * 2;
  int accel_z_axis = nunchuck_buf[4]; // * 2 * 2;
  
  int z_button = 1;
  int c_button = 1;

  // byte nunchuck_buf[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 ((nunchuck_buf[5] >> 0) & 1)
    z_button = 0;
  if ((nunchuck_buf[5] >> 1) & 1)
    c_button = 0;

  // byte nunchuck_buf[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 ((nunchuck_buf[5] >> 0) & 1) 
    z_button = 1;
  if ((nunchuck_buf[5] >> 1) & 1)
    c_button = 1;

  if ((nunchuck_buf[5] >> 2) & 1) 
    accel_x_axis += 2;
  if ((nunchuck_buf[5] >> 3) & 1)
    accel_x_axis += 1;

  if ((nunchuck_buf[5] >> 4) & 1)
    accel_y_axis += 2;
  if ((nunchuck_buf[5] >> 5) & 1)
    accel_y_axis += 1;

  if ((nunchuck_buf[5] >> 6) & 1)
    accel_z_axis += 2;
  if ((nunchuck_buf[5] >> 7) & 1)
    accel_z_axis += 1;

  //For finding Angle

  float joy_x_angle = abs(2.55 * (nunchuck_buf[0]) - 331.5);
  float joy_y_angle = abs(2.55 * (nunchuck_buf[1]) - 331.5);

  int angle = abs((atan(joy_y_angle / joy_x_angle) * 4068) / 71);

  if ( ( joy_x_angle < 6 && joy_x_angle > -6 ) && ( joy_y_angle < 6 && joy_y_angle > -6 ) ) {
    int angle = 254;
  }

  if (angle < 45){
    angle = 5.6666666666667 * (angle);
    if (angle <= 11){
      angle = 0;
    }
    else{
    }
  }
  
  else if (angle >= 45){
    angle = -5.6666666666667 * (angle) + 510;
    if (angle <= 11){
      angle = 0;
    }
    else{
    }
  }
  
  // For finding Direction

  int joy_x_axis_direction = 2.55 * (nunchuck_buf[0]) - 331.5;
  int joy_y_axis_direction = 2.55 * (nunchuck_buf[1]) - 331.5;

  int joy_x_axis_b = 255 - (abs(2.55 * (nunchuck_buf[0]) - 331.5));
  int joy_y_axis_b = 255 - (abs(2.55 * (nunchuck_buf[1]) - 331.5));
  
  int b = 255 - ( sqrt( sq ( 255 - joy_x_axis_b ) + sq ( 255 - joy_y_axis_b ) ) );

if (allowSerialWrite >= 50){ 

  if ( ( joy_x_axis_direction < 8 && joy_x_axis_direction > -8 ) && ( joy_y_axis_direction < 8 && joy_y_axis_direction > -8 ) ) {
  
    Serial.write(187);Serial.write(254);Serial.write(187);Serial.write(254);Serial.write(accel_x_axis);Serial.write(accel_y_axis);Serial.write(accel_z_axis);

  }

  else if (joy_y_axis_direction > abs(joy_x_axis_direction)) {

    if (joy_x_axis_direction < 0) {
    
      Serial.write(170);Serial.write(b);Serial.write(170);Serial.write(angle);Serial.write(accel_x_axis);Serial.write(accel_y_axis);Serial.write(accel_z_axis);
    
    }

    else if (joy_x_axis_direction > 0) {
    
      Serial.write(170);Serial.write(angle);Serial.write(170);Serial.write(b);Serial.write(accel_x_axis);Serial.write(accel_y_axis);Serial.write(accel_z_axis);
    
    }
    
  }

  else if (joy_y_axis_direction < (-1) * abs(joy_x_axis_direction)) {

    if (joy_x_axis_direction < 0) {
    
      Serial.write(187);Serial.write(b);Serial.write(187);Serial.write(angle);Serial.write(accel_x_axis);Serial.write(accel_y_axis);Serial.write(accel_z_axis);
    
    }
    
    else if (joy_x_axis_direction > 0) {
    
      Serial.write(187);Serial.write(angle);Serial.write(187);Serial.write(b);Serial.write(accel_x_axis);Serial.write(accel_y_axis);Serial.write(accel_z_axis);
    
    }

  }

  else if (joy_x_axis_direction > 0) {
    
    Serial.write(170);Serial.write(b);Serial.write(187);Serial.write(angle);Serial.write(accel_x_axis);Serial.write(accel_y_axis);Serial.write(accel_z_axis);
  
  }

  else if (joy_x_axis_direction < 0) {
  
    Serial.write(187);Serial.write(angle);Serial.write(170);Serial.write(b);Serial.write(accel_x_axis);Serial.write(accel_y_axis);Serial.write(accel_z_axis);
  
  }

  allowSerialWrite = 0;

}

allowSerialWrite++;  

  //  Serial.write(joy_x_axis, DEC);
  //  Serial.write(",");
  //  Serial.write(joy_y_axis, DEC);

  //  Serial.write("\r\n");

}

// 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;
}