double cache = 0;

void setup() {
  // put your setup code here, to run once:
  pinMode(A0, INPUT);
  pinMode(6, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  if (analogRead(A0) >= 512) {
    digitalWrite(6, HIGH);
  } else {
    digitalWrite(6, LOW);
  }
  cache = double(analogRead(A0)) / 204;
  Serial.println("Napiecie: " + String(cache));
}