#define pinsensor 2 
#define pinLED 4   
void setup() 
{
  Serial.begin(115200);
  pinMode(pinsensor, INPUT);
  pinMode(pinLED, OUTPUT);
}

void loop() 
{
  int api = digitalRead(pinsensor);
  if (api > 20)
    {
      digitalWrite(pinLED, HIGH);
      Serial.println(api);
    }
    else
    {
      digitalWrite(pinLED, LOW);
      Serial.println(api);
    }
  delay(1000);    
}