Here is the code:

```
#include <PID_v1.h>
#include <Wire.h>
#include <Servo.h>
Servo steer_servo;
//Gyro Variables
float elapsedTime, time, timePrev;
int gyro_error=0;
float Gyr_rawX, Gyr_rawY, Gyr_rawZ;
float Gyro_angle_x, Gyro_angle_y;
float Gyro_raw_error_x, Gyro_raw_error_y;
//Acc Variables
int acc_error=0;
float rad_to_deg = 180/3.141592654;
float Acc_rawX, Acc_rawY, Acc_rawZ;
float Acc_angle_x, Acc_angle_y;
float Acc_angle_error_x, Acc_angle_error_y;
float Total_angle_x, Total_angle_y;
/*working variables for PID*/
unsigned long lastTime;
double Input, Output, Setpoint;
double ITerm, lastInput;
double kp, ki, kd;
int SampleTime = 1000; //1 sec
double outMin, outMax;
bool inAuto = false;
void setup()
{
// put your setup code here, to run once:
Wire.begin(); //begin the wire comunication
Wire.beginTransmission(0x68); //begin, Send the slave adress (in this case 68)
Wire.write(0x6B); //make the reset (place a 0 into the 6B register)
Wire.write(0x00);
Wire.endTransmission(true); //end the transmission
//Gyro config
Wire.beginTransmission(0x68); //begin, Send the slave adress (in this case 68)
Wire.write(0x1B); //We want to write to the GYRO_CONFIG register (1B hex)
Wire.write(0x10); //Set the register bits as 00010000 (1000dps full scale)
Wire.endTransmission(true); //End the transmission with the gyro
//Acc config
Wire.beginTransmission(0x68); //Start communication with the address found during search.
Wire.write(0x1C); //We want to write to the ACCEL_CONFIG register
Wire.write(0x10); //Set the register bits as 00010000 (+/- 8g full scale range)
Wire.endTransmission(true);
Serial.begin(9600); //Remember to set this same baud rate to the serial monitor
time = millis(); //Start counting time in milliseconds
/*Here we calculate the acc data error before we start the loop
* I make the mean of 200 values, that should be enough*/
if(acc_error==0)
{
for(int a=0; a<200; a++)
{
Wire.beginTransmission(0x68);
Wire.write(0x3B); //Ask for the 0x3B register- correspond to AcX
Wire.endTransmission(false);
Wire.requestFrom(0x68,6,true);
Acc_rawX=(Wire.read()<<8|Wire.read())/4096.0 ; //each value needs two registres
Acc_rawY=(Wire.read()<<8|Wire.read())/4096.0 ;
Acc_rawZ=(Wire.read()<<8|Wire.read())/4096.0 ;
/*---X---*/
Acc_angle_error_x = Acc_angle_error_x + ((atan((Acc_rawY)/sqrt(pow((Acc_rawX),2) + pow((Acc_rawZ),2)))*rad_to_deg));
/*---Y---*/
Acc_angle_error_y = Acc_angle_error_y + ((atan(-1*(Acc_rawX)/sqrt(pow((Acc_rawY),2) + pow((Acc_rawZ),2)))*rad_to_deg));
if(a==199)
{
Acc_angle_error_x = Acc_angle_error_x/200;
Acc_angle_error_y = Acc_angle_error_y/200;
acc_error=1;
}
}
}//end of acc error calculation
/*Here we calculate the gyro data error before we start the loop
* I make the mean of 200 values, that should be enough*/
if(gyro_error==0)
{
for(int i=0; i<200; i++)
{
Wire.beginTransmission(0x68); //begin, Send the slave adress (in this case 68)
Wire.write(0x43); //First adress of the Gyro data
Wire.endTransmission(false);
Wire.requestFrom(0x68,4,true); //We ask for just 4 registers
Gyr_rawX=Wire.read()<<8|Wire.read(); //Once again we shif and sum
Gyr_rawY=Wire.read()<<8|Wire.read();
/*---X---*/
Gyro_raw_error_x = Gyro_raw_error_x + (Gyr_rawX/32.8);
/*---Y---*/
Gyro_raw_error_y = Gyro_raw_error_y + (Gyr_rawY/32.8);
if(i==199)
{
Gyro_raw_error_x = Gyro_raw_error_x/200;
Gyro_raw_error_y = Gyro_raw_error_y/200;
gyro_error=1;
}
}
}//end of gyro error calculation
steer_servo.attach(9);
}
void loop()
{
// put your main code here, to run repeatedly:
accelerometer();
}
void accelerometer()
{
timePrev = time; // the previous time is stored before the actual time read
time = millis(); // actual time read
elapsedTime = (time - timePrev) / 1000; //divide by 1000 in order to obtain seconds
//////////////////////////////////////Gyro read/////////////////////////////////////
Wire.beginTransmission(0x68); //begin, Send the slave adress (in this case 68)
Wire.write(0x43); //First adress of the Gyro data
Wire.endTransmission(false);
Wire.requestFrom(0x68,4,true); //We ask for just 4 registers
Gyr_rawX=Wire.read()<<8|Wire.read(); //Once again we shif and sum
Gyr_rawY=Wire.read()<<8|Wire.read();
/*Now in order to obtain the gyro data in degrees/seconds we have to divide first
the raw value by 32.8 because that's the value that the datasheet gives us for a 1000dps range*/
/*---X---*/
Gyr_rawX = (Gyr_rawX/32.8) - Gyro_raw_error_x;
/*---Y---*/
Gyr_rawY = (Gyr_rawY/32.8) - Gyro_raw_error_y;
Gyro_angle_x = Gyr_rawX*elapsedTime;
Gyro_angle_y = Gyr_rawY*elapsedTime;
Wire.beginTransmission(0x68); //begin, Send the slave adress (in this case 68)
Wire.write(0x3B); //Ask for the 0x3B register- correspond to AcX
Wire.endTransmission(false); //keep the transmission and next
Wire.requestFrom(0x68,6,true); //We ask for next 6 registers starting withj the 3B
Acc_rawX=(Wire.read()<<8|Wire.read())/4096.0 ; //each value needs two registres
Acc_rawY=(Wire.read()<<8|Wire.read())/4096.0 ;
Acc_rawZ=(Wire.read()<<8|Wire.read())/4096.0 ;
/*Now in order to obtain the Acc angles we use euler formula with acceleration values
after that we substract the error value found before*/
/*---X---*/
Acc_angle_x = (atan((Acc_rawY)/sqrt(pow((Acc_rawX),2) + pow((Acc_rawZ),2)))*rad_to_deg) - Acc_angle_error_x;
/*---Y---*/
Acc_angle_y = (atan(-1*(Acc_rawX)/sqrt(pow((Acc_rawY),2) + pow((Acc_rawZ),2)))*rad_to_deg) - Acc_angle_error_y;
Total_angle_x = 0.98 *(Total_angle_x + Gyro_angle_x) + 0.02*Acc_angle_x;
Total_angle_y = 0.98 *(Total_angle_y + Gyro_angle_y) + 0.02*Acc_angle_y;
Serial.print("Xº: ");
Serial.print(Total_angle_x);
Serial.print(" | ");
Serial.print("Yº: ");
Serial.print(Total_angle_y);
Serial.println(" ");
}
void Compute()
{
if(!inAuto) return;
unsigned long now = millis();
int timeChange = (now - lastTime);
if(timeChange>=SampleTime)
{
/*Compute all the working error variables*/
double error = Setpoint - Input;
ITerm += (ki * error);
if(ITerm > outMax) ITerm = outMax;
else if(ITerm < outMin) ITerm = outMin;
double dInput = (Input - lastInput);
/*Compute PID Output*/
Output = kp * error + ITerm - kd * dInput;
if(Output > outMax) Output = outMax;
else if(Output < outMin) Output = outMin;
/*Remember some variables for next time*/
lastInput = Input;
lastTime = now;
}
}
void SetTunings(double Kp = 10, double Ki = 0, double Kd = 0)
{
double SampleTimeInSec = ((double)SampleTime)/1000;
kp = Kp;
ki = Ki * SampleTimeInSec;
kd = Kd / SampleTimeInSec;
}
void SetSampleTime(int NewSampleTime)
{
if (NewSampleTime > 0)
{
double ratio = (double)NewSampleTime/(double)SampleTime;
ki *= ratio;
kd /= ratio;
SampleTime = (unsigned long)NewSampleTime;
}
}
void SetOutputLimits(double Min, double Max)
{
if(Min > Max) return;
outMin = Min;
outMax = Max;
if(Output > outMax) Output = outMax;
else if(Output < outMin) Output = outMin;
if(ITerm > outMax) ITerm = outMax;
else if(ITerm < outMin) ITerm = outMin;
}
void SetMode(int Mode)
{
bool newAuto = (Mode == AUTOMATIC);
if(newAuto && !inAuto)
{ /*we just went from manual to auto*/
Initialize();
}
inAuto = newAuto;
}
void Initialize()
{
lastInput = Input;
ITerm = Output;
if(ITerm > outMax) ITerm = outMax;
else if(ITerm < outMin) ITerm = outMin;
}
```