---

#define PR A0
#define LED1 3
#define LED2 5

void setup() {
  Serial.begin(9600);

  pinMode(PR, INPUT);
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
}

void loop() {
  int prValue = analogRead(PR);

  Serial.print("Value = ");
  Serial.println(prValue);

  int resistance = map(prValue, 0, 1023, 0, 20000);

  Serial.print("Resistance = ");
  Serial.print(resistance);
  Serial.println(" Ohm");

  if (resistance >= 3000) {
    digitalWrite(LED1, HIGH);
  } else {
    digitalWrite(LED1, LOW);
  }

  analogWrite(LED2, map(resistance, 0, 20000, 255, 0));

  delay(100);
}