const int cmd1_mot = D4;
const int cmd2_mot = D5; 

void setup() {
  pinMode(cmd1_mot, OUTPUT);
  pinMode(cmd2_mot, OUTPUT);
}

void avancer(int vitesse){
  analogWrite(cmd1_mot,vitesse);
  analogWrite(cmd2_mot,0);
}

void reculer(int vitesse){
  analogWrite(cmd2_mot,vitesse);
  analogWrite(cmd1_mot,0);
}

void stopper(){
  analogWrite(cmd1_mot,0);
  analogWrite(cmd2_mot,0);
}

void loop() {
  avancer(128); // vitesse moyenne [0 - 255]
  delay(1000);
  stopper();
  delay(1000);
  reculer(128);
  delay(1000);
  stopper();
  delay(1000);
}