Code by RabbiWood#0271 - Sun Aug 04 2019 19:15:18 GMT+0000 (Coordinated Universal Time)

Code Block Paste

const int Fridge = 2;
const int Freezer = 3;
const int DoorLED = 12;
const int Speaker = 13;
unsigned long startTime;
unsigned long currentTime;
const unsigned long period = 30000;

void setup() {
  Serial.begin(9600);
  pinMode(Fridge, INPUT_PULLUP);
  pinMode(Freezer, INPUT_PULLUP);
  pinMode(DoorLED, OUTPUT);
  pinMode(Speaker, OUTPUT);
  digitalWrite(DoorLED, HIGH);
  attachInterrupt(digitalPinToInterrupt(Fridge), wakeUp, HIGH);
  attachInterrupt(digitalPinToInterrupt(Freezer), wakeUp, HIGH);
}

bool awake = false;
void loop() {
  if (awake == false) {
    //We just awoke.
    startTime = millis();
    awake = true;
    Serial.print("Start Time  ");
    Serial.print(startTime);
  }
  
  //Now we are in the loop, start time is set......
  if ( (digitalRead(Fridge) == HIGH) || (digitalRead(Freezer) == HIGH) ){
     unsigned long elapsedms = startTime - millis();
     digitalWrite(DoorLED, HIGH);
    

     if(elapsedms >= period){ 
        tone(Speaker, 50, 500);
        }
  } else {
    //Go to sleep here
    GoToSleep(); 
  }
}

void GoToSleep() {
  Serial.println("Going to sleep now.");
  digitalWrite(DoorLED, LOW);
/* Enable these for you to compile */  
//  sleep_enable();
//  set_sleep_mode(SLEEP_MODE_PWR_DOWN);
  digitalWrite(DoorLED, LOW);
  awake = false;
//  sleep_cpu();
}

void wakeUp() {
  Serial.println("Just woke up!");
  //Enable this for you
  //sleep_disable();