http://mgprojecthub.com/?p=4622

ArduinoBluetoothRobot.ino

/*
    DIY Simple Arduino Bluetooth Controlled Robot Car
    Coder - Mayoogh Girish
    Website - http://mgprojecthub.com/
    Download the App :
*/

char data = 0;                //Variable for storing data

int RMA = 8;
int RMB = 9;
int LMA = 10;
int LMB = 11;

void setup()
{
  Serial.begin(9600);         //Sets the data rate in bits per second (baud) for serial data transmission
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(11, OUTPUT);
}
void loop()
{
  if (Serial.available() > 0)
  {
    data = Serial.read();      //Read the incoming data and store it into variable data
    Serial.print(data);        //Print Value of data in Serial monitor
    Serial.print("\n");        //New line
    
    
    if (data == 'S')
      stop_();
      
    else if (data == 'F')
      forward_();

    else if (data == 'B')
      backward_();

    else if (data == 'L')
      left_180();

    else if (data == 'R')
      right_180();

    else if (data == 'G')
      forwardLeft();

    else if (data == 'I')
      forwardRight();

    else if (data == 'H')
      backwardLeft();

    else if (data == 'J')
      backwardRight();
  }
}

void stop_() {
  Serial.print("STOP");
  digitalWrite(LMA, LOW);
  digitalWrite(LMB, LOW);
  digitalWrite(RMA, LOW);
  digitalWrite(RMB, LOW);
}

void forward_() {
  Serial.print("FORWARD");
  digitalWrite(LMA, HIGH);
  digitalWrite(LMB, LOW);
  digitalWrite(RMA, HIGH);
  digitalWrite(RMB, LOW);
}

void backward_() {
  Serial.print("BACKWARD");
  digitalWrite(LMA, LOW);
  digitalWrite(LMB, HIGH);
  digitalWrite(RMA, LOW);
  digitalWrite(RMB, HIGH);
}

void left_180() {
  Serial.print("LEFT 180");
  digitalWrite(LMA, LOW);
  digitalWrite(LMB, HIGH);
  digitalWrite(RMA, HIGH);
  digitalWrite(RMB, LOW);
}

void right_180() {
  Serial.print("RIGHT 180");
  digitalWrite(LMA, HIGH);
  digitalWrite(LMB, LOW);
  digitalWrite(RMA, LOW);
  digitalWrite(RMB, HIGH);
}

void forwardLeft() {
  Serial.print("FORWARD - LEFT");
  digitalWrite(LMA, LOW);
  digitalWrite(LMB, LOW);
  digitalWrite(RMA, HIGH);
  digitalWrite(RMB, LOW);
}

void forwardRight() {
  Serial.print("FORWARD - RIGHT");
  digitalWrite(LMA, HIGH);
  digitalWrite(LMB, LOW);
  digitalWrite(RMA, LOW);
  digitalWrite(RMB, LOW);
}

void backwardLeft() {
  Serial.print("BACKWARD - LEFT");
  digitalWrite(LMA, LOW);
  digitalWrite(LMB, LOW);
  digitalWrite(RMA, LOW);
  digitalWrite(RMB, HIGH);
}

void backwardRight() {
  Serial.print("BACKWARD - RIGHT");
  digitalWrite(LMA, LOW);
  digitalWrite(LMB, HIGH);
  digitalWrite(RMA, LOW);
  digitalWrite(RMB, LOW);
}