File content as of revision 2:f9f4d36c2367:

/*   Brushless gimbal controller with IMU (MPU050)
*
*    @author: Baser Kandehir 
*    @date: July 17, 2015
*    @license: Use this code however you'd like
*   
*    @description of the program: 
*    
*    This a one axis gimbal control program that takes roll angle from an IMU 
*    and  moves the gimbal brushless motor accordingly. Program is written with
*    PID algorithm but it uses only P for the time being and response is good
*    enough. Complete PID algorithm can be written by modifying gimbalPID function
*    and PID constants. 
*
*    Microcontroller: LPC1768  
*    IMU: MPU6050
*    Motor driver: 2x TB6612FNG
*
*   Note: For any mistakes or comments, please contact me.
*/

#include "mbed.h"
#include "MPU6050.h"
#include "ledControl.h"
#include "brushlessController_TB6612FNG.h"

Serial pc(USBTX, USBRX);       // Create terminal link
MPU6050 mpu6050;               // mpu6050 object from MPU6050 classs
Ticker toggler1;               // Ticker for led toggling
Ticker filter;                 // Ticker for periodic call to compFilter funcçs 
Ticker gimbal;                 // Periodic routine for PID control of gimbal system

/* Function prototypes */
void toggle_led1();
void toggle_led2();
void compFilter();
void gimbalPID();

float pitchAngle = 0;
float rollAngle = 0;

/* Variables to be used in gimbalPID funct. */
float Kp = 1;
float Ki = 0; 
float Kd = 0; 
float set_point = -30;         // which angle camera should stay
float errorMargin = 5;         // error margin in degress
float proportional = 0;
float last_proportional =0;
float integral = 0;
float derivative = 0;
float errorPID = 0;            // error is already declared at mbed libraries

int main()
{
    pc.baud(9600);                               // baud rate: 9600
    i2c.frequency(400000);                       // fast i2c: 400 kHz
    mpu6050.whoAmI();                            // Communication test: WHO_AM_I register reading 
    mpu6050.calibrate(accelBias,gyroBias);       // Calibrate MPU6050 and load biases into bias registers
    pc.printf("Calibration is completed. \r\n"); 
    mpu6050.init();                              // Initialize the sensor
    pc.printf("MPU6050 is initialized for operation.. \r\n\r\n");
    
    filter.attach(&compFilter, 0.005);           // Call the complementaryFilter func. every 5 ms (200 Hz sampling period)
    gimbal.attach(&gimbalPID,  0.001);           // Call the gimbalPID func. every 1 ms
    while(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() {mpu6050.complementaryFilter(&pitchAngle, &rollAngle);}

void gimbalPID()
{
    bool dir;  // direction of movement
 
    proportional = set_point - rollAngle;        
    integral += proportional; 
    derivative = proportional - last_proportional;
    last_proportional = proportional;
    
    errorPID = (Kp * proportional) + (Ki * integral) + (Kd * derivative); 
    (errorPID > 0)?(dir = 1):(dir = 0);
    
    if(abs(errorPID) > errorMargin)  // Within error margin motor wont move. This is for stabilizing the gimbal system
        brushlessControl(dir, 0);    // No need for a delay time because gimbalPID function is periodic
}