#include <Wire.h>
#include "Kalman.h"
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,16,2);

Kalman kalmanX;
Kalman kalmanY;

uint8_t IMUAddress = 0x68;

/* IMU Data */
int16_t accX;
int16_t accY;
int16_t accZ;
int16_t tempRaw;
int16_t gyroX;
int16_t gyroY;
int16_t gyroZ;

double accXangle; // Angle calculate using the accelerometer
double accYangle;
double temp;
double gyroXangle = 180; // Angle calculate using the gyro
double gyroYangle = 180;
double compAngleX = 180; // Calculate the angle using a Kalman filter
double compAngleY = 180;
double kalAngleX; // Calculate the angle using a Kalman filter
double kalAngleY;

uint32_t timer;

void setup() {   

   Serial.begin(115200);
   Wire.begin();
   Serial.begin(9600);
   lcd.init();                       
   lcd.backlight();               

   i2cWrite(0x6B,0x00); // Disable sleep mode         
   kalmanX.setAngle(180); // Set starting angle
   kalmanY.setAngle(180);
   timer = micros();
}

void loop() {
   /* Update all the values */
   uint8_t* data = i2cRead(0x3B,14);   
   accX = ((data[0] << 8) | data[1]);
   accY = ((data[2] << 8) | data[3]);
   accZ = ((data[4] << 8) | data[5]);   
   tempRaw = ((data[6] << 8) | data[7]);   
   gyroX = ((data[8] << 8) | data[9]);
   gyroY = ((data[10] << 8) | data[11]);
   gyroZ = ((data[12] << 8) | data[13]);

   /* Calculate the angls based on the different sensors and algorithm */
   accYangle = (atan2(accX,accZ)+PI)*RAD_TO_DEG;
   accXangle = (atan2(accY,accZ)+PI)*RAD_TO_DEG;     

   double gyroXrate = (double)gyroX/131.0;
   double gyroYrate = -((double)gyroY/131.0);
   gyroXangle += kalmanX.getRate()*((double)(micros()-timer)/1000000); // Calculate gyro angle using the unbiased rate
   gyroYangle += kalmanY.getRate()*((double)(micros()-timer)/1000000);

   kalAngleX = kalmanX.getAngle(accXangle, gyroXrate, (double)(micros()-timer)/1000000); // Calculate the angle using a Kalman filter
   kalAngleY = kalmanY.getAngle(accYangle, gyroYrate, (double)(micros()-timer)/1000000);
   timer = micros();

   lcd.setCursor (0,0);
   lcd.print ("X=");
   lcd.print (kalAngleX,0);
   lcd.print (" Y=");
   lcd.print (kalAngleY,0);
   delay (100);
   lcd.clear ();

   // The accelerometer's maximum samples rate is 1kHz
}
void i2cWrite(uint8_t registerAddress, uint8_t data){
   Wire.beginTransmission(IMUAddress);
   Wire.write(registerAddress);
   Wire.write(data);
   Wire.endTransmission(); // Send stop
}
uint8_t* i2cRead(uint8_t registerAddress, uint8_t nbytes) {
   uint8_t data[nbytes];   
   Wire.beginTransmission(IMUAddress);
   Wire.write(registerAddress);
   Wire.endTransmission(false); // Don't release the bus
   Wire.requestFrom(IMUAddress, nbytes); // Send a repeated start and then release the bus after reading
   for(uint8_t i = 0; i < nbytes; i++)
     data [i]= Wire.read();
   return data;
}