char dataIn = 'S';        
int pinLeft = 10;     
int pinRight = 11;       
int pinEnableLeftRight = 9;
int pinForward = 5;
int pinBack = 6;
int pinSpeedForwardBack = 3;
int pinfrontLights = 8;
int pinbackLights = 7;
char determinant;         
char det;                 
int velocity = 0;

void setup()  
{        
Serial.begin(9600);  
pinMode(pinLeft, OUTPUT);
pinMode(pinRight, OUTPUT);
pinMode(pinForward, OUTPUT);
pinMode(pinBack, OUTPUT);
pinMode(pinEnableLeftRight, OUTPUT);
pinMode(pinSpeedForwardBack, OUTPUT);
pinMode(pinfrontLights, OUTPUT);
pinMode(pinbackLights, OUTPUT);
}

void loop()
{  
    det = check();
      while (det == 'F')   //naprijed
      {      
          digitalWrite(pinEnableLeftRight, HIGH);  
          analogWrite(pinSpeedForwardBack, velocity); 
          digitalWrite(pinLeft,HIGH);
          digitalWrite(pinRight,HIGH);   
          digitalWrite(pinForward,LOW);
          digitalWrite(pinBack,HIGH);         
          det = check();           
      }   
      while (det == 'B')  //iza
      {     
          digitalWrite(pinEnableLeftRight, HIGH);  
          analogWrite(pinSpeedForwardBack, velocity);
          digitalWrite(pinLeft,HIGH);
          digitalWrite(pinRight,HIGH);   
          digitalWrite(pinForward,HIGH);
          digitalWrite(pinBack,LOW);         
          det = check();           
      }  

      while (det == 'L')   //lijevo
      {      
          digitalWrite(pinEnableLeftRight, HIGH);  
          analogWrite(pinSpeedForwardBack, 0);
          digitalWrite(pinLeft,LOW);
          digitalWrite(pinRight,HIGH);   
          digitalWrite(pinForward,HIGH);
          digitalWrite(pinBack,HIGH);        
          det = check();           
      }   
      while (det == 'R')   //desno
      {     
          digitalWrite(pinEnableLeftRight, HIGH);  
          analogWrite(pinSpeedForwardBack, 0); 
          digitalWrite(pinLeft,HIGH);
          digitalWrite(pinRight,LOW);   
          digitalWrite(pinForward,HIGH);
          digitalWrite(pinBack,HIGH);         
          det = check();           
      } 
      
      while (det == 'I')  
      {      
          digitalWrite(pinEnableLeftRight,LOW);  
          analogWrite(pinSpeedForwardBack, velocity);
          digitalWrite(pinLeft,HIGH);
          digitalWrite(pinRight,LOW);   
          digitalWrite(pinForward,LOW);
          digitalWrite(pinBack,HIGH);                 
          det = check();           
      }   
      while (det == 'J')  
      {       
          digitalWrite(pinEnableLeftRight, LOW);  
          analogWrite(pinSpeedForwardBack, velocity);
          digitalWrite(pinLeft,HIGH);
          digitalWrite(pinRight,LOW);   
          digitalWrite(pinForward,HIGH);
          digitalWrite(pinBack,LOW);         
          det = check();           
      }           
      while (det == 'G')  
      {  
          digitalWrite(pinEnableLeftRight, LOW);  
          analogWrite(pinSpeedForwardBack, velocity);
          digitalWrite(pinLeft,LOW);
          digitalWrite(pinRight,HIGH);   
          digitalWrite(pinForward,LOW);
          digitalWrite(pinBack,HIGH);           
          det = check();           
      }     
      while (det == 'H')  
      { 
          digitalWrite(pinEnableLeftRight, LOW);  
          analogWrite(pinSpeedForwardBack, velocity);
          digitalWrite(pinLeft,LOW);
          digitalWrite(pinRight,HIGH);   
          digitalWrite(pinForward,HIGH);
          digitalWrite(pinBack,LOW);           
          det = check();                                               
      }    
      while (det == 'S')  
      { 
          digitalWrite(pinEnableLeftRight, HIGH);  
          analogWrite(pinSpeedForwardBack, 0);
          digitalWrite(pinLeft,HIGH);
          digitalWrite(pinRight,HIGH);   
          digitalWrite(pinForward,HIGH);
          digitalWrite(pinBack,HIGH);        
          det = check();  
      }
      while (det == 'U')  
      { 
          digitalWrite(pinfrontLights, HIGH);           
          det = check();  
      }
      while (det == 'u')   
      { 
          digitalWrite(pinfrontLights, LOW);           
          det = check();  
      }
      while (det == 'W')   
      { 
          digitalWrite(pinbackLights, HIGH);           
          det = check();  
      }
      while (det == 'w')   
      { 
          digitalWrite(pinbackLights, LOW); 
          det = check();  
      }
}

int check()
{
  if (Serial.available() > 0)    //provjerava dostupnost serijske komunikacije. 
  {    
    dataIn = Serial.read();  //provijerava dolazni podatak i sprema u'dataIn'.
        if (dataIn == 'F') 
        {      
          determinant = 'F';
        }   
        else if (dataIn == 'B') 
        {  
          determinant = 'B';  
        }
        else if (dataIn == 'L')   
        {  
          determinant = 'L'; 
        }
        else if (dataIn == 'R')   
        {  
          determinant = 'R';
        }  
        else if (dataIn == 'I')   
        {  
          determinant = 'I';  
        }   
        else if (dataIn == 'J')   
        {   
          determinant = 'J'; 
        }           
        else if (dataIn == 'G')  
        { 
          determinant = 'G';  
        }     
        else if (dataIn == 'H')   
        { 
          determinant = 'H';  
        }    
        else if (dataIn == 'S')  
        {
          determinant = 'S';
        } 
      
        else if (dataIn == 'U')  
        {
          determinant = 'U'; 
        }
        else if (dataIn == 'u')  
        {
          determinant = 'u'; 
        }
        else if (dataIn == 'W')  
        {
          determinant = 'W'; 
        }
        
        else if (dataIn == 'w')  
        {
          determinant = 'w'; 
        }
  } 
return determinant; 
}