int vp;
int valeurLed;
void setup() {
  pinMode(3, OUTPUT);
  pinMode(A0, INPUT);
  Serial.begin(9600);
}

void loop() {
  vp = analogRead(A0);
  valeurLed = map(vp, 0, 1023, 0, 255);
  analogWrite(3, valeurLed);
  Serial.print("VP = ");
  Serial.print(vp);
  Serial.print(" valeurLed = ");
  Serial.println(valeurLed);
  delay(20);
}