int motor1Pin1 = 3; 
int motor1Pin2 = 4; 
int enable1Pin = 6; 
int motor2Pin1 = 8; 
int motor2Pin2 = 9; 
int enable2Pin = 11; 
int state;
int flag = 0; // memastikan bahwa serial hanya dicetak setelah status
int stateStop = 0;
void setup() {
  // set pin sebagai output:
  pinMode(motor1Pin1, OUTPUT);
  pinMode(motor1Pin2, OUTPUT);
  pinMode(enable1Pin, OUTPUT);
  pinMode(motor2Pin1, OUTPUT);
  pinMode(motor2Pin2, OUTPUT);
  pinMode(enable2Pin, OUTPUT);
  // set enable1Pin dan enable2Pin tinggi sehingga motor dapat hidup:
  digitalWrite(enable1Pin, HIGH);
  digitalWrite(enable2Pin, HIGH);
  // inisialisasi komunikasi serial pada 9600 bit per detik:
  Serial.begin(9600);
}
void loop() {
  // jika ada tanggal yang dikirim, baca dan simpan dalam status
  if (Serial.available() > 0) {
    state = Serial.read();
    flag = 0;
  }
  // jika keadaan 'F' motor DC akan maju
  if (state == 'F') {
    digitalWrite(motor1Pin1, HIGH);
    digitalWrite(motor1Pin2, LOW);
    digitalWrite(motor2Pin1, LOW);
    digitalWrite(motor2Pin2, HIGH);
    if (flag == 0) {
      Serial.println("Go Forward!");
      flag = 1;
    }
  }
  // jika keadaan 'R' motor akan belok kiri
  else if (state == 'R') {
    digitalWrite(motor1Pin1, HIGH);
    digitalWrite(motor1Pin2, LOW);
    digitalWrite(motor2Pin1, LOW);
    digitalWrite(motor2Pin2, LOW);
    if (flag == 0) {
      Serial.println("Turn LEFT");
      flag = 1;
    }
    delay(1500);
    state = 3;
    stateStop = 1;
  }
  // jika keadaan 'S' motor akan Berhenti
  else if (state == 'S' || stateStop == 1) {
    digitalWrite(motor1Pin1, LOW);
    digitalWrite(motor1Pin2, LOW);
    digitalWrite(motor2Pin1, LOW);
    digitalWrite(motor2Pin2, LOW);
    if (flag == 0) {
      Serial.println("STOP!");
      flag = 1;
    }
    stateStop = 0;
  }
  // jika keadaan 'L' motor akan belok kanan
  else if (state == 'L') {
    digitalWrite(motor1Pin1, LOW);
    digitalWrite(motor1Pin2, LOW);
    digitalWrite(motor2Pin1, LOW);
    digitalWrite(motor2Pin2, HIGH);
    if (flag == 0) {
      Serial.println("Turn RIGHT");
      flag = 1;
    }
    delay(1500);
    state = 3;
    stateStop = 1;
  }
  // jika keadaan 'B' motor akan Terbalik
  else if (state == 'B') {
    digitalWrite(motor1Pin1, LOW);
    digitalWrite(motor1Pin2, HIGH);
    digitalWrite(motor2Pin1, HIGH);
    digitalWrite(motor2Pin2, LOW);
    if (flag == 0) {
      Serial.println("Reverse!");
      flag = 1;
    }
  }
  // Untuk tujuan debugging
  //Serial.println(state);
}