    http://arduino.cc/forum/index.php/topic,109987.0.html
    http://code.google.com/p/arduino/issues/detail?id=958
  * ========================================================================= */
-
-
-
-// uncomment "OUTPUT_READABLE_QUATERNION" if you want to see the actual
-// quaternion components in a [w, x, y, z] format (not best for parsing
-// on a remote host such as Processing or something though)
-//#define OUTPUT_READABLE_QUATERNION
-
-// uncomment "OUTPUT_READABLE_EULER" if you want to see Euler angles
-// (in degrees) calculated from the quaternions coming from the FIFO.
-// Note that Euler angles suffer from gimbal lock (for more info, see
-// http://en.wikipedia.org/wiki/Gimbal_lock)
-//#define OUTPUT_READABLE_EULER
-
-// uncomment "OUTPUT_READABLE_YAWPITCHROLL" if you want to see the yaw/
-// pitch/roll angles (in degrees) calculated from the quaternions coming
-// from the FIFO. Note this also requires gravity vector calculations.
-// Also note that yaw/pitch/roll angles suffer from gimbal lock (for
-// more info, see: http://en.wikipedia.org/wiki/Gimbal_lock)
-#define OUTPUT_READABLE_YAWPITCHROLL
-
-// uncomment "OUTPUT_READABLE_REALACCEL" if you want to see acceleration
-// components with gravity removed. This acceleration reference frame is
-// not compensated for orientation, so +X is always +X according to the
-// sensor, just without the effects of gravity. If you want acceleration
-// compensated for orientation, us OUTPUT_READABLE_WORLDACCEL instead.
-//#define OUTPUT_READABLE_REALACCEL
-
-// uncomment "OUTPUT_READABLE_WORLDACCEL" if you want to see acceleration
-// components with gravity removed and adjusted for the world frame of
-// reference (yaw is relative to initial orientation, since no magnetometer
-// is present in this case). Could be quite handy in some cases.
-//#define OUTPUT_READABLE_WORLDACCEL
-
-// uncomment "OUTPUT_TEAPOT" if you want output that matches the
-// format used for the InvenSense teapot demo
-//#define OUTPUT_TEAPOT
-
 
 
 #define LED_PIN 13 // (Arduino is 13, Teensy is 11, Teensy++ is 6)

// Arduino Wire library is required if I2Cdev I2CDEV_ARDUINO_WIRE implementation
// is used in I2Cdev.h
#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
    #include "Wire.h"
#endif

// class default I2C address is 0x68

// ================================================================

void setup() {
  // join I2C bus (I2Cdev library doesn't do this automatically)
#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
  Wire.begin();
  TWBR = 24; // 400kHz I2C clock (200kHz if CPU is 8MHz)
#elif I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE
  Fastwire::setup(400, true);
#endif

  // initialize serial communication
  // (115200 chosen because it is required for Teapot Demo output, but it's
  // really up to you depending on your project)
  Serial.begin(115200);
  while (!Serial); // wait for Leonardo enumeration, others continue immediately

  // NOTE: 8MHz or slower host processors, like the Teensy @ 3.3v or Ardunio
  // Pro Mini running at 3.3v, cannot handle this baud rate reliably due to
  // the baud timing being too misaligned with processor ticks. You must use
  // 38400 or slower in these cases, or use some kind of external separate
  // crystal solution for the UART timer.

  // initialize device
  Serial.println(F("Initializing I2C devices..."));
  mpu.initialize();

  // verify connection
  Serial.println(F("Testing device connections..."));
  Serial.println(mpu.testConnection() ? F("MPU6050 connection successful") : F("MPU6050 connection failed"));

  // load and configure the DMP
  Serial.println(F("Initializing DMP..."));
  devStatus = mpu.dmpInitialize();

  // supply your own gyro offsets here, scaled for min sensitivity
  //mpu.setXGyroOffset(220);
  //mpu.setYGyroOffset(-376);
  //mpu.setZGyroOffset(-85);
  //mpu.setZAccelOffset(1788); // 1688 factory default for my test chip

  // make sure it worked (returns 0 if so)
  if (devStatus == 0) {
    // turn on the DMP, now that it's ready
    Serial.println(F("Enabling DMP..."));
    mpu.setDMPEnabled(true);

    // enable Arduino interrupt detection
    Serial.println(F("Enabling interrupt detection (Arduino external interrupt 0)..."));
    attachInterrupt(digitalPinToInterrupt(3), dmpDataReady, RISING);
    mpuIntStatus = mpu.getIntStatus();

    // set our DMP Ready flag so the main loop() function knows it's okay to use it
    Serial.println(F("DMP ready! Waiting for first interrupt..."));
    dmpReady = true;

    // get expected DMP packet size for later comparison
    packetSize = mpu.dmpGetFIFOPacketSize();
  } else {
    // ERROR!
    // 1 = initial memory load failed
    // 2 = DMP configuration updates failed
    // (if it's going to break, usually the code will be 1)
    Serial.print(F("DMP Initialization failed (code "));
    Serial.print(devStatus);
    Serial.println(F(")"));
  }

  // configure LED for output
  pinMode(LED_PIN, OUTPUT);

  while (Serial.available() && Serial.read()); // empty buffer
}



// ================================================================
// ===                    MAIN PROGRAM LOOP                     ===
// ================================================================

void loop() {
  char command;

  // if programming failed, don't try to do anything
  if (!dmpReady) return;

  // reset interrupt flag and get INT_STATUS byte
  mpuInterrupt = false;
  mpuIntStatus = mpu.getIntStatus();

  // get current FIFO count
  fifoCount = mpu.getFIFOCount();

  // check for overflow (this should never happen unless our code is too inefficient)
  if ((mpuIntStatus & 0x10) || fifoCount == 1024) {
    // reset so we can continue cleanly
    mpu.resetFIFO();
    Serial.println(F("FIFO overflow!"));
    // otherwise, check for DMP data ready interrupt (this should happen frequently)
  } else if (mpuIntStatus & 0x02) {
    // wait for correct available data length, should be a VERY short wait
    while (fifoCount < packetSize) fifoCount = mpu.getFIFOCount();

    // read a packet from FIFO
    mpu.getFIFOBytes(fifoBuffer, packetSize);

    // track FIFO count here in case there is > 1 packet available
    // (this lets us immediately read more without waiting for an interrupt)
    fifoCount -= packetSize;

    // Get Euler angles in degrees and Acceleration in world-frame
    mpu.dmpGetQuaternion(&q, fifoBuffer);
    mpu.dmpGetAccel(&aa, fifoBuffer);
    mpu.dmpGetGravity(&gravity, &q);
    mpu.dmpGetYawPitchRoll(ypr, &q, &gravity);
    mpu.dmpGetLinearAccel(&aaReal, &aa, &gravity);
    mpu.dmpGetLinearAccelInWorld(&aaWorld, &aaReal, &q);

    if (Serial.available()) {
      command = Serial.read();
      switch (command) {
        case 'i':
          Serial.println("i\ttrue");
          break;
        case 'g':
          Serial.print("g\t");
          Serial.print(ypr[0] * 180 / M_PI);
          Serial.print("\t");
          Serial.print(ypr[1] * 180 / M_PI);
          Serial.print("\t");
          Serial.println(ypr[2] * 180 / M_PI);
          break;
        case 'a':
          Serial.print("a\t");
          Serial.print(aaWorld.x);
          Serial.print("\t");
          Serial.print(aaWorld.y);
          Serial.print("\t");
          Serial.println(aaWorld.z);
          break;
        default:
          Serial.print("ERROR - Command ");
          Serial.print(command);
          Serial.println(" unknown!");
      }

      // blink LED to indicate activity
      blinkState = !blinkState;
      digitalWrite(LED_PIN, blinkState);
    }
  }
}
