File content as of revision 24:f2503d1256ad:

#include "mbed.h"
#include "MPU6050_6Axis_MotionApps20.h"
#include "debug.h"

// MPU
MPU6050 mpu;
InterruptIn dataReady(P0_15);

// 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

volatile bool mpuInterrupt = false;
void dataReadyISR() {
    mpuInterrupt = true;
}

/* Returns a pointer to an array containing the most recent data.  Will return NULL if unable to 
   get new data (expect this to happen).  Requires the mpu to be initialized. */
VectorInt16 *receive_data()
{
    static uint32_t n_overflows = 0;

    // do nothing if dmp not ready
    if (!dmpReady) return NULL;

    while (!mpuInterrupt && fifoCount < packetSize);

    // Reset interrupt
    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) {
        PC_PRINTLN("**** FIFO OVERFLOW ****");
        n_overflows++;
        // reset so we can continue cleanly
        mpu.resetFIFO();
        // otherwise, check for DMP data ready interrupt or another packet to process (this should happen frequently)
    } else if (mpuIntStatus & 0x02 || fifoCount > packetSize) {
        // Wait for a full packet - should be very short wait
        while (fifoCount < packetSize) fifoCount = mpu.getFIFOCount();

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

        // Get acceleration data
        mpu.dmpGetAccel(&aa, fifoBuffer); 
        return &aa;
    }
    
    return NULL;
}

bool receive_close() {
    // Disable DMP and clear fifo
    mpu.setDMPEnabled(false);
    mpu.resetFIFO();
    
    return true;
}

bool receive_init() {
    PC_PRINTLN("Initializing MPU");
    mpu.initialize();
    PC_PRINTLN("MPU initialized, initializing DMP");
    devStatus = mpu.dmpInitialize();
    
    if (devStatus == 0) {
        mpu.setDMPEnabled(true);
        packetSize = mpu.dmpGetFIFOPacketSize();
        
        PC_PRINTLN("DMP Initialized successfully!");
        dmpReady = true;
        dataReady.rise(dataReadyISR);
        return true;
    } else { // ERROR
        PC_PRINTLNF("Error initializing MPU (code %d)", devStatus);
        DIE(DMP_ERROR_RATE);
        return false;
    }
    
    PC_PRINTLN("Receive init success, capturing data...");
}