int ledPin = LED_BUILTIN;
int buttonPin = 2; // Button connected to D2 and GND
int flare_threshold = 20;
bool active = false;

void setup() {
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  Serial.begin(9600);
  Serial.println("Starting doorbell sensor");
}

void loop() {
  int val = digitalRead(buttonPin);
  
  if (val == LOW) {
    delay(flare_threshold); // catch flares
    val = digitalRead(buttonPin);
    
    if (val == LOW && active == false) {
      Serial.println("RING");
      digitalWrite(ledPin, HIGH);
      active = true;
      delay(250);
    }
    else if (val == HIGH) {
      Serial.print("flare (<");
      Serial.print(flare_threshold);
      Serial.println(")");
    }
  }
  else {
    active = false;
    digitalWrite(ledPin, LOW);
  }
  
}