int motor1Pin1 = 2;
int motor1Pin2 = 3;
int motor1EnablePin = 10;
int motor2Pin1 = 4;
int motor2Pin2 = 5;
int motor2EnablePin = 11;
int state;
int Speed = 100; 
int flag=0;
int stateStop=0;
void setup() {
    Serial.begin(9600);
    pinMode(motor1Pin1, OUTPUT);
    pinMode(motor1Pin2, OUTPUT);
    pinMode(motor1EnablePin, OUTPUT);
    pinMode(motor2EnablePin, OUTPUT);
    pinMode(motor2Pin1, OUTPUT);
    pinMode(motor2Pin2, OUTPUT);
}

void loop() {
    if(Serial.available() > 0){     
      state = Serial.read(); 
      if(state > 5){
         Speed = state;}  
      flag=0;
    }
    if (state == 1) {
        forword();
        if(flag == 0){
          Serial.println("Forward!");
          flag=1;
        }
    }
    else if (state == 2) {
        turnLeft();
        if(flag == 0){
          Serial.println("LEFT");
          flag=1;
        }
    }
    else if (state == 3) {
        Stop();
        if(flag == 0){
          Serial.println("STOP!");
          flag=1;
        }
    }
    else if (state == 5) {
        turnRight();
        if(flag == 0){
          Serial.println("Turn RIGHT");
          flag=1;
        }
    }
    else if (state == 4) {
        backword();
        if(flag == 0){
          Serial.println("Reverse!");
          flag=1;
        }
    }
}

void forword(){
    digitalWrite(motor1Pin1, LOW);
    digitalWrite(motor1Pin2, HIGH); 
    digitalWrite(motor2Pin1, HIGH);
    digitalWrite(motor2Pin2, LOW);
    analogWrite(motor1EnablePin, Speed);
    analogWrite(motor2EnablePin, Speed);
}

void backword(){
    digitalWrite(motor1Pin1, HIGH);
    digitalWrite(motor1Pin2, LOW); 
    digitalWrite(motor2Pin1, LOW);
    digitalWrite(motor2Pin2, HIGH);
    analogWrite(motor1EnablePin, Speed);
    analogWrite(motor2EnablePin, Speed);
}

void turnRight(){
    digitalWrite(motor1Pin1, LOW);
    digitalWrite(motor1Pin2, LOW); 
    digitalWrite(motor2Pin1, LOW);
    digitalWrite(motor2Pin2, HIGH);
    analogWrite(motor1EnablePin, Speed);
    analogWrite(motor2EnablePin, Speed);
}

void turnLeft(){
    digitalWrite(motor1Pin1, HIGH);
    digitalWrite(motor1Pin2, LOW); 
    digitalWrite(motor2Pin1, LOW);
    digitalWrite(motor2Pin2, LOW);
    analogWrite(motor1EnablePin, Speed);
    analogWrite(motor2EnablePin, Speed);
}

void Stop(){
    digitalWrite(motor1Pin1, LOW);
    digitalWrite(motor1Pin2, LOW); 
    digitalWrite(motor2Pin1, LOW);
    digitalWrite(motor2Pin2, LOW);
    analogWrite(motor1EnablePin, Speed);
    analogWrite(motor2EnablePin, Speed);
}