int motor1pin1 = 2;
int motor1pin2 = 3;

int motor2pin1 = 4;
int motor2pin2 = 5;
 
char command; 
 
void setup() 
{       
  Serial.begin(9600);  //Set the baud rate to your Bluetooth module.
  // Motors pins
  pinMode(motor1pin1, OUTPUT);
  pinMode(motor1pin2, OUTPUT);
  pinMode(motor2pin1, OUTPUT);
  pinMode(motor2pin2, OUTPUT);
}
 
void loop(){
  if(Serial.available() > 0){ 
    command = Serial.read();
    Stop(); //initialize with motors stoped
    //Change pin mode only if new command is different from previous.   
    //Serial.println(command);
    switch(command){
    case 'F':  
      forward();
      break;
    case 'B':  
       back();
      break;
    case 'L':  
      left();
      break;
    case 'R':
      right();
      break;
    }
  } 
}
 
void forward()
{
  Serial.println("FORWARD");
  // Two motors on one side
  digitalWrite(motor1pin1, LOW);
  digitalWrite(motor1pin2, HIGH);

  digitalWrite(motor2pin1, HIGH);
  digitalWrite(motor2pin2, LOW);
}
 
void back()
{
  Serial.println("BACKWARD");
  // Two motors on one side
  digitalWrite(motor1pin1, HIGH);
  digitalWrite(motor1pin2, LOW);

  digitalWrite(motor2pin1, LOW);
  digitalWrite(motor2pin2, HIGH);
}
 
void right()
{
  Serial.println("RIGHT");
  digitalWrite(motor1pin1, HIGH);
  digitalWrite(motor1pin2, LOW);

  digitalWrite(motor2pin1, HIGH);
  digitalWrite(motor2pin2, LOW);
}

void left()
{
  Serial.println("LEFT");
  digitalWrite(motor1pin1, LOW);
  digitalWrite(motor1pin2, HIGH);

  digitalWrite(motor2pin1, LOW);
  digitalWrite(motor2pin2, HIGH);
}
 
void Stop()
{
  digitalWrite(motor1pin1, LOW);
  digitalWrite(motor1pin2, LOW);

  digitalWrite(motor2pin1, LOW);
  digitalWrite(motor2pin2, LOW);
}
