int led = 5;
int Vr_pin = 8;
void setup()
{
  pinMode(led, OUTPUT);
  pinMode(Vr_pin,INPUT);
  Serial.begin(9600);
}
void loop()
{
  for (int i = 0; i < 255; i++) {
    analogWrite(led, i);
    delay(5);
  }
  for (int i = 255; i > 0; i--) {
    analogWrite(led, i);
    delay(5);
  }
  delay(1000);
  int Vr = analogRead(Vr_pin);
  int Vr1 = map (Vr,0,1023,0,5);
  Serial.println(Vr1);
  delay(500);
}