// https://wokwi.com/projects/423998501637049345

const byte buzzer = 9;
const byte ldHeart = 8;    // heartbeat LED

const byte alarm = 7;   // pushbutton proxy for alarm condition
const byte shutUp = 6;  // silence the beeping
const byte reset = 5;   // pushbutton to reset action

# define PRESST LOW     // active low pushbuttons

// heartbeat and alarm
bool beeping;     // do we want noise with our heartbeat?
bool hasAlarmed;  // have we said so once?

void setup() {
  pinMode(alarm , INPUT_PULLUP);
  pinMode(shutUp, INPUT_PULLUP);
  pinMode(reset , INPUT_PULLUP);

  pinMode(ldHeart , OUTPUT);
}

unsigned long now;

void loop() {
  now = millis();

// run the heartbeat (and tone if beeping)
  heartBeeper();  // run the LED heartbeat, maybe mke noise


// raise alarm when the PU has gone over 15, once only
//  here not if (PU > 15.0) {
// but on a pushbutton
  bool alarmCondition = digitalRead(alarm) == LOW;
  if (alarmCondition) {
    if (!hasAlarmed) beeping = true;
    hasAlarmed = true;
  }


// button kills the beeping
  bool shutUpButton = digitalRead(shutUp) == LOW;
  if (shutUpButton) beeping = false;


// reset the alarm mechanism for next time
  bool resetButton = digitalRead(reset) == LOW;
  if (resetButton) {
    beeping = false;
    hasAlarmed = false;
  }
}

//

// heartbeat/buzzer preferences
# define onTime 333
# define offTime  444
# define buzzerFrequency 777

// LED heart beat, and noise if
void heartBeeper()
{
  static bool on;
  static unsigned lastTime;

  if (now - lastTime < (on ? onTime : offTime)) return;

  lastTime = now;
  on = !on;

  if (on) {
    if (beeping)
      tone(buzzer, buzzerFrequency);

    digitalWrite(ldHeart, HIGH);
  }
  else {
    noTone(buzzer);
    digitalWrite(ldHeart, LOW);   
  }
}