File content as of revision 2:7be1ac6eb8cb:

/*#include "mbed.h"
#include "inv_mpu.h"
#include "mdcompat.h"
Serial pc(USBTX,USBRX);
DigitalOut led(LED1);
int main()
{
    imu_init();
    
    while(1){
        led=1;
        wait_ms(100);
        led=0;
        wait_ms(100);
    }  
}*/

#include "SparkFunMPU9250-DMP.h"
#include "mdcompat.h"

Serial pc(USBTX,USBRX);
DigitalOut led(LED1);
MPU9250_DMP imu;
char datax[1]={0};
long DEBUG[]={2,2,2,2};
int main() 
{
  pc.baud(115200);
  pc.printf("Hello World\n");
  // Call imu.begin() to verify communication and initialize
    pc.printf("imu.begin()is being run\n");
  if (imu.begin() != INV_SUCCESS){
    pc.printf("imu.begin() have failed");
    while (1){
      pc.printf("Unable to communicate with MPU-9250");
      pc.printf("Check connections, and try again.\n");
      wait_ms(5000);
    }
  }
  pc.printf("imu.begin() suceeded\n");
  imu.dmpBegin(DMP_FEATURE_6X_LP_QUAT | // Enable 6-axis quat
               DMP_FEATURE_GYRO_CAL, // Use gyro calibration
              20); // Set DMP FIFO rate to 20 Hz
  // DMP_FEATURE_LP_QUAT can also be used. It uses the 
  // accelerometer in low-power mode to estimate quat's.
  // DMP_FEATURE_LP_QUAT and 6X_LP_QUAT are mutually exclusive
  pc.printf("imu.dmpBegin() suceeded\n");

while(1){
  // Check for new data in the FIFO
  led=1;
  wait_ms(500);
  led=0;
  wait_ms(500);
  mbed_i2c_read((unsigned char)0x68,(unsigned char)0x75,1,datax);
  pc.printf("%d",datax[0]);
  if ( imu.fifoAvailable() ){//fifo is not being available
    led=0;
    wait_ms(100);
    led=1;
    wait_ms(100);
    // Use dmpUpdateFifo to update the ax, gx, mx, etc. values
    if ( imu.dmpUpdateFifo(DEBUG) == INV_SUCCESS){
      // computeEulerAngles can be used -- after updating the
      // quaternion values -- to estimate roll, pitch, and yaw
      imu.computeEulerAngles();
      //printIMUData();
     #if 1
      pc.printf("%lf",DEBUG[0]);
      pc.printf("\t");
      pc.printf("%lf",DEBUG[1]);
      pc.printf("\t");
      pc.printf("%lf",DEBUG[2]);
      pc.printf("\t");
      pc.printf("%lf\n ",DEBUG[3]);
     #endif
    }
  }
}
  return 0;
}

void printIMUData(void)
{  
  // After calling dmpUpdateFifo() the ax, gx, mx, etc. values
  // are all updated.
  // Quaternion values are, by default, stored in Q30 long
  // format. calcQuat turns them into a float between -1 and 1
  float q0 = imu.calcQuat(imu.qw);
  float q1 = imu.calcQuat(imu.qx);
  float q2 = imu.calcQuat(imu.qy);
  float q3 = imu.calcQuat(imu.qz);
  
  pc.printf("R:%lf  P:%lf   Y:%lf \n", imu.roll,imu.pitch,imu.yaw);
}