title: MPU6050 output yaw pitch and roll with Arduino
body: <p>I'm trying to read yaw, pitch and roll with MPU6050 and Arduino, but I always get overflow, if I use the function yprx() in the loop without waiting for any input I get the correct values, the problem in this solution is that I need the three values of ypr[] just when called from an input in Serial.read().</p>
  
  <p><img src="https://i.stack.imgur.com/4PXFG.gif" alt="yaw, pitch and roll"></p>
  
  <pre><code>#include "I2Cdev.h"
  
  #include "MPU6050_6Axis_MotionApps20.h"
  
  // 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
  // specific I2C addresses may be passed as a parameter here
  // AD0 low = 0x68 (default for SparkFun breakout and InvenSense evaluation board)
  // AD0 high = 0x69
  MPU6050 mpu;
  //MPU6050 mpu(0x69); // &lt;-- use for AD0 high
  
  
  
  
  // 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
  bool blinkState = false;
  
  // MPU control/status vars
  bool dmpReady = false;  // set true if DMP init was successful
  uint8_t mpuIntStatus;   // holds actual interrupt status byte from MPU
  uint8_t devStatus;      // return status after each device operation (0 = success, !0 = error)
  uint16_t packetSize;    // expected DMP packet size (default is 42 bytes)
  uint16_t fifoCount;     // count of all bytes currently in FIFO
  uint8_t fifoBuffer[64]; // FIFO storage buffer
  
  // orientation/motion vars
  Quaternion q;           // [w, x, y, z]         quaternion container
  VectorInt16 aa;         // [x, y, z]            accel sensor measurements
  VectorInt16 aaReal;     // [x, y, z]            gravity-free accel sensor measurements
  VectorInt16 aaWorld;    // [x, y, z]            world-frame accel sensor measurements
  VectorFloat gravity;    // [x, y, z]            gravity vector
  float euler[3];         // [psi, theta, phi]    Euler angle container
  float ypr[3];           // [yaw, pitch, roll]   yaw/pitch/roll container and gravity vector
  
  // packet structure for InvenSense teapot demo
  uint8_t teapotPacket[14] = { '$', 0x02, 0,0, 0,0, 0,0, 0,0, 0x00, 0x00, '\r', '\n' };
  
  
  
  // ================================================================
  // ===               INTERRUPT DETECTION ROUTINE                ===
  // ================================================================
  
  volatile bool mpuInterrupt = false;     // indicates whether MPU interrupt pin has gone high
  void dmpDataReady() {
      mpuInterrupt = true;
  }
  
  
  
  // ================================================================
  // ===                      INITIAL SETUP                       ===
  // ================================================================
  
  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"));
  
      // wait for ready
      /*
      Serial.println(F("\nSend any character to begin DMP programming and demo: "));
      while (Serial.available() &amp;&amp; Serial.read()); // empty buffer
      while (!Serial.available());                 // wait for data
      while (Serial.available() &amp;&amp; Serial.read()); // empty buffer again
  */
      // 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(76);
      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(0, 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);
  }
  
  
  
  // ================================================================
  // ===                    MAIN PROGRAM LOOP                     ===
  // ================================================================
  
  void loop() {
      if (Serial.available() &gt; 0) {
        Serial.println("Inserisci lettera");
        char comando = toLowerCase(Serial.read());
          // usciamo i caratteri a A ricevuti via seriale per accendere il led
          if (comando == 'a') { 
             yprx();  
            //Mandare risposta al Raspberry che  stato acceso       
          }
          // gli altri caratteri lo spengono
          else {
             Serial.println("Noyhing to do!");
             //Mandare risposta al Raspberry che  stato spento
          }        
     } 
  }
  
  void yprx(){
    // if programming failed, don't try to do anything
      if (!dmpReady) return;
  
      // wait for MPU interrupt or extra packet(s) available
      while (!mpuInterrupt &amp;&amp; fifoCount &lt; packetSize) {
          // other program behavior stuff here
          // .
          // .
          //Serial.println("TEST");
          // if you are really paranoid you can frequently test in between other
          // stuff to see if mpuInterrupt is true, and if so, "break;" from the
          // while() loop to immediately process the MPU data
          // .
          // .
          // .
      }
  
      // 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 &amp; 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 &amp; 0x02) {
          // wait for correct available data length, should be a VERY short wait
          while (fifoCount &lt; packetSize) fifoCount = mpu.getFIFOCount();
  
          // read a packet from FIFO
          mpu.getFIFOBytes(fifoBuffer, packetSize);
  
          // track FIFO count here in case there is &gt; 1 packet available
          // (this lets us immediately read more without waiting for an interrupt)
          fifoCount -= packetSize;
  
          #ifdef OUTPUT_READABLE_QUATERNION
              // display quaternion values in easy matrix form: w x y z
              mpu.dmpGetQuaternion(&amp;q, fifoBuffer);
              Serial.print("quat\t");
              Serial.print(q.w);
              Serial.print("\t");
              Serial.print(q.x);
              Serial.print("\t");
              Serial.print(q.y);
              Serial.print("\t");
              Serial.println(q.z);
          #endif
  
          #ifdef OUTPUT_READABLE_EULER
              // display Euler angles in degrees
              mpu.dmpGetQuaternion(&amp;q, fifoBuffer);
              mpu.dmpGetEuler(euler, &amp;q);
              Serial.print("euler\t");
              Serial.print(euler[0] * 180/M_PI);
              Serial.print("\t");
              Serial.print(euler[1] * 180/M_PI);
              Serial.print("\t");
              Serial.println(euler[2] * 180/M_PI);
          #endif
  
          #ifdef OUTPUT_READABLE_YAWPITCHROLL
              // display Euler angles in degrees
              mpu.dmpGetQuaternion(&amp;q, fifoBuffer);
              mpu.dmpGetGravity(&amp;gravity, &amp;q);
              mpu.dmpGetYawPitchRoll(ypr, &amp;q, &amp;gravity);
              Serial.print("ypr\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);
          #endif
  
          #ifdef OUTPUT_READABLE_REALACCEL
              // display real acceleration, adjusted to remove gravity
              mpu.dmpGetQuaternion(&amp;q, fifoBuffer);
              mpu.dmpGetAccel(&amp;aa, fifoBuffer);
              mpu.dmpGetGravity(&amp;gravity, &amp;q);
              mpu.dmpGetLinearAccel(&amp;aaReal, &amp;aa, &amp;gravity);
              Serial.print("areal\t");
              Serial.print(aaReal.x);
              Serial.print("\t");
              Serial.print(aaReal.y);
              Serial.print("\t");
              Serial.println(aaReal.z);
          #endif
  
          #ifdef OUTPUT_READABLE_WORLDACCEL
              // display initial world-frame acceleration, adjusted to remove gravity
              // and rotated based on known orientation from quaternion
              mpu.dmpGetQuaternion(&amp;q, fifoBuffer);
              mpu.dmpGetAccel(&amp;aa, fifoBuffer);
              mpu.dmpGetGravity(&amp;gravity, &amp;q);
              mpu.dmpGetLinearAccel(&amp;aaReal, &amp;aa, &amp;gravity);
              mpu.dmpGetLinearAccelInWorld(&amp;aaWorld, &amp;aaReal, &amp;q);
              Serial.print("aworld\t");
              Serial.print(aaWorld.x);
              Serial.print("\t");
              Serial.print(aaWorld.y);
              Serial.print("\t");
              Serial.println(aaWorld.z);
          #endif
  
          #ifdef OUTPUT_TEAPOT
              // display quaternion values in InvenSense Teapot demo format:
              teapotPacket[2] = fifoBuffer[0];
              teapotPacket[3] = fifoBuffer[1];
              teapotPacket[4] = fifoBuffer[4];
              teapotPacket[5] = fifoBuffer[5];
              teapotPacket[6] = fifoBuffer[8];
              teapotPacket[7] = fifoBuffer[9];
              teapotPacket[8] = fifoBuffer[12];
              teapotPacket[9] = fifoBuffer[13];
              Serial.write(teapotPacket, 14);
              teapotPacket[11]++; // packetCount, loops at 0xFF on purpose
          #endif
  
          // blink LED to indicate activity
          blinkState = !blinkState;
          digitalWrite(LED_PIN, blinkState);
      }
  }
  </code></pre>
  
  <p>This is the output I get:</p>
  
  <pre><code>Initializing I2C devices...
  Testing device connections...
  MPU6050 connection successful
  Initializing DMP...
  Enabling DMP...
  Enabling interrupt detection (Arduino external interrupt 0)...
  DMP ready! Waiting for first interrupt...
  Inserisci lettera
  FIFO overflow!
  Inserisci lettera
  Inserisci lettera
  FIFO overflow!
  Inserisci lettera
  FIFO overflow!
  </code></pre>