4WD Car Base

/*
  Software open source
  by Marco C.
  maggio 2018
  4WD Car
*/
const int motorA1  = 5;
const int motorA2  = 6;
const int motorB1  = 10;
const int motorB2  = 11;
int state;
int vSpeed = 200;   // la velocità va da 0 a 255
void setup() {
  pinMode(motorA1, OUTPUT);
  pinMode(motorA2, OUTPUT);
  pinMode(motorB1, OUTPUT);
  pinMode(motorB2, OUTPUT);
  Serial.begin(9600);
}
void loop() {
  if (Serial.available() > 0) {
    state = Serial.read();
    Stop();
  }
  //AVANTI
  //se ricevo la lettera A
  if (state == 'A') {
    analogWrite(motorA1, vSpeed);
    analogWrite(motorA2, 0);
    analogWrite(motorB1, vSpeed);
    analogWrite(motorB2, 0);
  }
  //INDIETRO
  else if (state == 'B') {
    analogWrite(motorA1, 0);
    analogWrite(motorA2, vSpeed);
    analogWrite(motorB1, 0);
    analogWrite(motorB2, vSpeed);
  }
  //SINISTRA
  else if (state == 'C') {
    analogWrite(motorA1, 200);
    analogWrite(motorA2, 0);
    analogWrite(motorB1, 0);
    analogWrite(motorB2, 200);
  }
  //DESTRA
  else if (state == 'D') {
    analogWrite(motorA1, 0);
    analogWrite(motorA2, 200);
    analogWrite(motorB1, 200);
    analogWrite(motorB2, 0);
  }
  //STOP
  else if (state == 'E') {
    analogWrite(motorA1, 0);
    analogWrite(motorA2, 0);
    analogWrite(motorB1, 0);
    analogWrite(motorB2, 0);
  }
}
void Stop() {
  analogWrite(motorA1, 0);
  analogWrite(motorA2, 0);
  analogWrite(motorB1, 0);
  analogWrite(motorB2, 0);
}