#include <LCD_I2C.h>

LCD_I2C lcd(0x27, 16, 2);

#define TRIG_PIN  5
#define ECHO_PIN  4
#define BUZZER_PIN  2
#define ENABLE_PIN  6

int freq = 1800;
int distance;
long duration;
bool en = false;

void setup() {
  Serial.begin(9600);
  lcd.begin();
  lcd.backlight();

  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(ENABLE_PIN, INPUT_PULLUP);
}

void loop() {
  distance = distanceCM(TRIG_PIN, ECHO_PIN);
  duration = distance * 5;
  lcd.setCursor(0, 0);
  lcd.print("Jarak: " + String(distance) + " cm  ");

  if(digitalRead(ENABLE_PIN) == 0){
    tone(BUZZER_PIN, 2500);
    while(digitalRead(ENABLE_PIN) == 0){}
    en = !en;
    noTone(BUZZER_PIN);
  }
  if(en){
    lcd.setCursor(0, 1);
    lcd.print("en:ON ");
  }else{
    lcd.setCursor(0, 1);
    lcd.print("en:OFF");
  }

  if (en && distance <= 100) {
    alarm(duration);
    lcd.setCursor(8, 1);
    lcd.print("B:HIDUP");
  } else {
    lcd.setCursor(8, 1);
    lcd.print("B:MATI ");
  }
}

void alarm(int time) {
  tone(BUZZER_PIN, freq);
  delay(time);
  noTone(BUZZER_PIN);
  delay(time);
}

float distanceCM(int TRIG, int ECHO) {
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);

  float duration_us = pulseIn(ECHO, HIGH);
  float distance_cm = 0.0343 * duration_us / 2;
  return distance_cm;
}