int m1a = 9;
int m1b = 10;
int m2a = 11;
int m2b = 12;
#define led A1
#define horn A0

char val;

void setup()
{
  pinMode(led, OUTPUT);
  pinMode(horn, OUTPUT);
  digitalWrite(led, LOW);
  digitalWrite(horn, LOW);
  pinMode(m1a, OUTPUT);  // Digital pin 10 set as output Pin
  pinMode(m1b, OUTPUT);  // Digital pin 11 set as output Pin
  pinMode(m2a, OUTPUT);  // Digital pin 12 set as output Pin
  pinMode(m2b, OUTPUT);  // Digital pin 13 set as output Pin
  Serial.begin(9600);
}

void loop()
{
  while (Serial.available() > 0)
  {
    val = Serial.read();
    Serial.println(val);
  }

  if ( val == 'F') // Forward
  {
    digitalWrite(m1a, HIGH);
    digitalWrite(m1b, LOW);
    digitalWrite(m2a, HIGH);
    digitalWrite(m2b, LOW);
  }
  else if (val == 'B') // Backward
  {
    digitalWrite(m1a, LOW);
    digitalWrite(m1b, HIGH);
    digitalWrite(m2a, LOW);
    digitalWrite(m2b, HIGH);
    digitalWrite(horn, HIGH);
    delay(100);
    digitalWrite(horn, LOW);
    delay(100);
  }

  else if (val == 'L') //Left
  {
    digitalWrite(m1a, LOW);
    digitalWrite(m1b, LOW);
    digitalWrite(m2a, HIGH);
    digitalWrite(m2b, LOW);
  }
  else if (val == 'R') //Right
  {
    digitalWrite(m1a, HIGH);
    digitalWrite(m1b, LOW);
    digitalWrite(m2a, LOW);
    digitalWrite(m2b, LOW);
  }

  else if (val == 'S') //Stop
  {
    digitalWrite(m1a, LOW);
    digitalWrite(m1b, LOW);
    digitalWrite(m2a, LOW);
    digitalWrite(m2b, LOW);
  }
  else if (val == 'I') //Forward Right
  {
    digitalWrite(m1a, HIGH);
    digitalWrite(m1b, LOW);
    digitalWrite(m2a, LOW);
    digitalWrite(m2b, LOW);
  }
  else if (val == 'J') //Backward Right
  {
    digitalWrite(m1a, LOW);
    digitalWrite(m1b, HIGH);
    digitalWrite(m2a, LOW);
    digitalWrite(m2b, LOW);
  }
  else if (val == 'G') //Forward Left
  {
    digitalWrite(m1a, LOW);
    digitalWrite(m1b, LOW);
    digitalWrite(m2a, HIGH);     digitalWrite(m2b, LOW);
  }
  else if (val == 'H') //Backward Left
  {
    digitalWrite(m1a, LOW);
    digitalWrite(m1b, LOW);
    digitalWrite(m2a, LOW);
    digitalWrite(m2b, HIGH);
  }
  else if (val == 'V') //horn on
  {
    digitalWrite(horn, HIGH);
  }
  else if (val == 'v') //horn off
  {
    digitalWrite(horn, LOW);
  }

  else if (val == 'X') //led on
  {
    digitalWrite(led, HIGH);
  }
  else if (val == 'x') //led off
  {
    digitalWrite(led, LOW);
  }
}