File content as of revision 0:40b56bdec1d2:

#include "mbed.h"
#include "MPU6050.h"
#include "ledControl.h"
#include "brushlessController_L293D.h"

/* Defined in the MPU6050.cpp file  */
// I2C i2c(p9,p10);         // setup i2c (SDA,SCL)  

Serial ftdi(p13,p14);    // default baud rate: 9600
MPU6050 mpu6050;         // class: MPU6050, object: mpu6050 
Ticker toggler1;
Ticker filter;           

void toggle_led1();
void toggle_led2();
void complementaryFilter(float* pitch, float* roll);
void compFilter();

float pitchAngle = 0;
float rollAngle = 0;
int prevStep = 0;               // previous step for the brushless motor
int errorMargin = 6;   // error margin in degrees for stabilizing the gimbal system
int setPoint = 0;               // set point in degrees for the gimbal system 

int main() 
{
    ftdi.baud(9600);                            // baud rate: 9600
    i2c.frequency(400000);                      // fast i2c: 400 kHz
    mpu6050.whoAmI();                           // Communication test: WHO_AM_I register reading 
 //   wait(1);
    mpu6050.calibrate(accelBias,gyroBias);      // Calibrate MPU6050 and load biases into bias registers
    ftdi.printf("Calibration is completed. \r\n");
 //   wait(0.5);
    mpu6050.init();                             // Initialize the sensor
 //   wait(1);
    ftdi.printf("MPU6050 is initialized for operation.. \r\n\r\n");
  //  wait_ms(500);
    
    while(1) 
    {
        filter.attach(&compFilter, 0.005);    // Call the complementaryFilter func. every 5 ms (200 Hz sampling period)
         
        if (abs(rollAngle - setPoint) < errorMargin)
        {
            // Do not move if above statement is true
            led4 = 1;
        }          
        else if(rollAngle > setPoint)
        {
            oneStep(0,30, &prevStep);
            led4 = 0;
        }
        else 
        {   
            oneStep(1,30, &prevStep);
            led4 = 0;
        }
        wait_ms(5);   // wait for new rollAngle data to arrive
    }
}

void toggle_led1() {ledToggle(1);}
void toggle_led2() {ledToggle(2);}

/* This function is created to avoid address error that caused from Ticker.attach func */ 
void compFilter() {complementaryFilter(&pitchAngle, &rollAngle);}

void complementaryFilter(float* pitch, float* roll)
{
    /* Get actual acc value */
    mpu6050.readAccelData(accelData);
    mpu6050.getAres();
    ax = accelData[0]*aRes - accelBias[0];
    ay = accelData[1]*aRes - accelBias[1];
    az = accelData[2]*aRes - accelBias[2]; 

    /* Get actual gyro value */
    mpu6050.readGyroData(gyroData);
    mpu6050.getGres();     
    gx = gyroData[0]*gRes;  // - gyroBias[0];      // Results are better without extracting gyroBias[i]
    gy = gyroData[1]*gRes;  // - gyroBias[1]; 
    gz = gyroData[2]*gRes;  // - gyroBias[2]; 

    float pitchAcc, rollAcc;

    /* Integrate the gyro data(deg/s) over time to get angle */
    *pitch += gx * dt;  // Angle around the X-axis
    *roll -=  gy * dt;  // Angle around the Y-axis
    
    /* Turning around the X-axis results in a vector on the Y-axis
    whereas turning around the Y-axis results in a vector on the X-axis. */
    pitchAcc = atan2f((float)accelData[1], (float)accelData[2])*180/PI;
    rollAcc  = atan2f((float)accelData[0], (float)accelData[2])*180/PI;
    
    /* Apply Complementary Filter */
    *pitch = *pitch * 0.98 + pitchAcc * 0.02;
    *roll  = *roll  * 0.98 + rollAcc  * 0.02;   
}