void setup() {
  pinMode(A0, INPUT);
  Serial.begin(9600);
  float vpt = 0;
  pinMode(13, OUTPUT);
  
}

void loop() {
  int maxbit = 1023;
  int maxvolt = 5;
  int nilaipotensio =  analogRead(A0);
  float vpt = (float)nilaipotensio / maxbit*maxvolt;

  Serial.print("Nilai pin A0:");
  Serial.print(nilaipotensio);

  
  Serial.println("nilai volt =");
  Serial.print(vpt);

  if(vpt > 2.5)
  digitalWrite(13, HIGH);
  else
  digitalWrite(13, LOW);

}