/*
=== Task 3 - PIR Motion Alert Using Boolean Logic ===
              Author: Roberto Palozzo
=====================================================
*/

const int PIR_PIN = 4;              // PIR motion sensor output pin
const int BUZZER_PIN = 15;          // passive buzzer pin

bool afterHours = true;             // manually simulates whether it's after working hours

// Plays a rising/falling siren tone by sweeping the buzzer frequency
// up and down between 600Hz and 1600Hz, one step per call
void startSiren() {
  static int frequency = 600;       // keeps its value between calls (only initialised once)
  static int direction = 20;        // how much to change the frequency each call, and which way

  tone(BUZZER_PIN, frequency);      // play the current frequency
  frequency += direction;           // step the frequency up or down

  if (frequency >= 1600) {
    direction = -20;                // hit the top, start sweeping down
  }
  else if (frequency <= 600) {
    direction = 20;                 // hit the bottom, start sweeping up
  }
}

// Stops the siren sound
void stopSiren() {
  noTone(BUZZER_PIN);
}

void setup() {
  Serial.begin(115200);

  pinMode(PIR_PIN, INPUT);          // PIR sensor as input
  pinMode(BUZZER_PIN, OUTPUT);      // buzzer as output

  stopSiren();                      // make sure the buzzer starts silent
}

void loop() {
  int motionDetected = digitalRead(PIR_PIN);   // read the sensor fresh every loop

  // Sound the alarm only when BOTH conditions are true:
  // motion is detected AND it's currently after hours
  if (afterHours == true && motionDetected == HIGH) {
    startSiren();
    Serial.println("Detected movements. ALARM!");
  }
  else {
    stopSiren();
    Serial.println("Undetected movements. All Good! ");
  }

  delay(100);                       // small pause between readings
}