#define LED 5

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode ( LED, OUTPUT );
}

int istEin = 0;

void loop() {
  int analogWert = analogRead(A0);
  Serial.println(analogWert);

  // Einschalten, wenn Temp grösser 25°
  if ( (analogWert < 512) && (istEin == 0) ) {
    digitalWrite ( LED, HIGH );
    Serial.println ("AN");
    istEin = 1;
  }

  // Ausschalten, wenn Temp kleiner 20°
  if ( analogWert > 530 && istEin == 1 ) {
    digitalWrite ( LED, LOW );
    Serial.println ("AUS");
    istEin = 0;
  }

  delay (200);
}