File content as of revision 3:88737ad5c803:

/*   MPU6050 example with I2C interface on LPC1768 
*
*    @author: Baser Kandehir 
*    @date: July 9, 2015
*    @license: Use this code however you'd like
*   
*    @description of the program: 
*    
*    First of all most of the credit goes to Kris Winer for his useful MPU6050 code.
*    I rewrite the code in my way using class prototypes and my comments. This program
*    can be a starter point for more advanced projects including quadcopters, balancing
*    robots etc. Program takes accelerometer and gyroscope data from the MPU6050 registers
*    and calibrates them for better results. And writes accel and gyro x,y,z data to the
*    terminal. I will use this code later on for sensor fusion with a compass to get pitch,
*    roll and yaw angles. After that I am planning to use some filtering algorithms like
*    Kalman Filter and Complementary filter. I will keep updating the code as I write them.
*   
*    @connections:
*-------------------------------------------------------------- 
*    |LPC1768|        |Peripherals|
*    Pin 9 ---------> SDA of MPU6050
*    Pin 10 --------> SCL of MPU6050
*    Pin 13 --------> (TX) RX pin of the FTDI or Bluetooth etc.
*    Pin 14 --------> (RX) TX pin of the FTDI or Bluetooth etc.
*    GND -----------> GND of any peripheral
*    VOUT (3.3 V) --> VCC of MPU6050
*---------------------------------------------------------------
*   Note: For any mistakes or comments, please contact me.
*/

#include "mbed.h"
#include "MPU6050.h"
#include "ledControl.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 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) 
    {
//        /* 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]; 
//        
//        ftdi.printf(" _____________________________________________________________  \r\n");
//        ftdi.printf("| Accelerometer(g) | ax=%.3f | ay=%.3f | az=%.3f                \r\n",ax,ay,az);
//        ftdi.printf("| Gyroscope(deg/s) | gx=%.3f | gy=%.3f | gz=%.3f                \r\n",gx,gy,gz);
//        ftdi.printf("|_____________________________________________________________  \r\n\r\n");
//        
//        wait(2.5);
                
        filter.attach(&compFilter, 0.005);    // Call the complementaryFilter func. every 5 ms (200 Hz sampling period)
        
        ftdi.printf(" _______________\r\n");
        ftdi.printf("| Pitch: %.3f   \r\n",pitchAngle);
        ftdi.printf("| Roll:  %.3f   \r\n",rollAngle);
        ftdi.printf("|_______________\r\n\r\n");
        
        wait(1);
    }
}

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;   
}