File content as of revision 0:98f7c7d55051:

// SDA --- A4
// SCL --- A5

#include "mbed.h"
#include "MPU6050.h"

float sum = 0;
uint32_t sumCount = 0;

MPU6050 mpu6050;
Timer t;
Serial pc(USBTX, USBRX); // tx, rx

int main(){
    pc.baud(9600);

    //Set up I2C
    i2c.frequency(400000);  // use fast (400 kHz) I2C
    t.start();

    // Read the WHO_AM_I register, this is a good test of communication
    uint8_t whoami = mpu6050.readByte(MPU6050_ADDRESS, WHO_AM_I_MPU6050);  // Read WHO_AM_I register for MPU-6050
    pc.printf("I AM 0x%x\n\r", whoami);
    pc.printf("I SHOULD BE 0x68\n\r");

    if (whoami == 0x68){
        pc.printf("MPU6050 is online...");
        wait(1);

        mpu6050.MPU6050SelfTest(SelfTest); // Start by performing self test and reporting values
        pc.printf("x-axis self test: acceleration trim within : ");
        pc.printf("%f", SelfTest[0]);
        pc.printf("% of factory value \n\r");
        pc.printf("y-axis self test: acceleration trim within : ");
        pc.printf("%f", SelfTest[1]);
        pc.printf("% of factory value \n\r");
        pc.printf("z-axis self test: acceleration trim within : ");
        pc.printf("%f", SelfTest[2]);
        pc.printf("% of factory value \n\r");
        pc.printf("x-axis self test: gyration trim within : ");
        pc.printf("%f", SelfTest[3]);
        pc.printf("% of factory value \n\r");
        pc.printf("y-axis self test: gyration trim within : ");
        pc.printf("%f", SelfTest[4]);
        pc.printf("% of factory value \n\r");
        pc.printf("z-axis self test: gyration trim within : ");
        pc.printf("%f", SelfTest[5]);
        pc.printf("% of factory value \n\r");
        wait(1);

        if(SelfTest[0] < 1.0f && SelfTest[1] < 1.0f && SelfTest[2] < 1.0f && SelfTest[3] < 1.0f && SelfTest[4] < 1.0f && SelfTest[5] < 1.0f) {
            mpu6050.resetMPU6050(); // Reset registers to default in preparation for device calibration
            mpu6050.calibrateMPU6050(gyroBias, accelBias); // Calibrate gyro and accelerometers, load biases in bias registers
            mpu6050.initMPU6050();
            pc.printf("MPU6050 initialized for active data mode....\n\r"); // Initialize device for active mode read of acclerometer, gyroscope, and temperature

            pc.printf("\nMPU6050 passed self test... Initializing");
            wait(2);
        } else pc.printf("\nDevice did not the pass self-test!\n\r");
    } else {
        pc.printf("Could not connect to MPU6050: \n\r");
        pc.printf("%#x \n",  whoami);
        while(1) ; // Loop forever if communication doesn't happen
    }

    while(1) {

        // If data ready bit set, all data registers have new data
        if(mpu6050.readByte(MPU6050_ADDRESS, INT_STATUS) & 0x01) {  // check if data ready interrupt
            mpu6050.readAccelData(accelCount);  // Read the x/y/z adc values
            mpu6050.getAres();

            // Now we'll calculate the accleration value into actual g's
            ax = (float)accelCount[0]*aRes - accelBias[0];  // get actual g value, this depends on scale being set
            ay = (float)accelCount[1]*aRes - accelBias[1];
            az = (float)accelCount[2]*aRes - accelBias[2];

            mpu6050.readGyroData(gyroCount);  // Read the x/y/z adc values
            mpu6050.getGres();

            // Calculate the gyro value into actual degrees per second
            gx = (float)gyroCount[0]*gRes; // - gyroBias[0];  // get actual gyro value, this depends on scale being set
            gy = (float)gyroCount[1]*gRes; // - gyroBias[1];
            gz = (float)gyroCount[2]*gRes; // - gyroBias[2];

            tempCount = mpu6050.readTempData();  // Read the x/y/z adc values
            temperature = (tempCount) / 340. + 36.53; // Temperature in degrees Centigrade
        }

        Now = t.read_us();
        deltat = (float)((Now - lastUpdate)/1000000.0f) ; // set integration time by time elapsed since last filter update
        lastUpdate = Now;

        sum += deltat;
        sumCount++;

        if(lastUpdate - firstUpdate > 10000000.0f) {
            beta = 0.04;  // decrease filter gain after stabilized
            zeta = 0.015; // increasey bias drift gain after stabilized
        }

        // Pass gyro rate as rad/s
        mpu6050.MadgwickQuaternionUpdate(ax, ay, az, gx*PI/180.0f, gy*PI/180.0f, gz*PI/180.0f);

        // Serial print and/or display at 0.5 s rate independent of data rates
        delt_t = t.read_ms() - count;
        if (delt_t > 500) { // update LCD once per half-second independent of read rate

            yaw   = atan2(2.0f * (q[1] * q[2] + q[0] * q[3]), q[0] * q[0] + q[1] * q[1] - q[2] * q[2] - q[3] * q[3]);
            pitch = -asin(2.0f * (q[1] * q[3] - q[0] * q[2]));
            roll  = atan2(2.0f * (q[0] * q[1] + q[2] * q[3]), q[0] * q[0] - q[1] * q[1] - q[2] * q[2] + q[3] * q[3]);
            pitch *= 180.0f / PI;
            yaw   *= 180.0f / PI;
            roll  *= 180.0f / PI;

            pc.printf("Yaw, Pitch, Roll: %f %f %f\n\r", yaw, pitch, roll);
            pc.printf("average rate = %f\n\r", (float) sumCount/sum);

            count = t.read_ms();
            sum = 0;
            sumCount = 0;
        }
    }

}