int sensorPin = 0;
int ledPin = 13;     
void setup() 
{
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);
}
void loop()
{
  int sensorValue;
  double total;
  int num;
  sensorValue = analogRead(sensorPin);
  num = sensorValue;
  if (sensorValue >= 511)
  {
    digitalWrite(ledPin, HIGH);
    total = sensorValue * 0.00488;
    Serial.print(total);
    Serial.println("V");
    num = sensorValue;
    while (num == sensorValue)
    {
      sensorValue = analogRead(sensorPin);
    }
  }
  else if (sensorValue < 511)
  {
    digitalWrite(ledPin, LOW);
    total = sensorValue * 0.00488;
    Serial.print(total);
    Serial.println("V");
    num = sensorValue;
    while (num == sensorValue)
    {
      sensorValue = analogRead(sensorPin);
    }
  }
}