#include <LiquidCrystal.h>

//Display
LiquidCrystal lcd(12, 11, 10, 9, 8, 7);
//Sensor
#define ECHO_PIN 2
#define TRIG_PIN 3

float cm;
int buzzer = A0;

void setup() {
  lcd.begin(16, 2);
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
}

float readDistanceCM() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  int duration = pulseIn(ECHO_PIN, HIGH);
  return duration * 0.034 / 2;
}

void loop() {
  float distance = readDistanceCM();
  bool isNearby = distance < 100;
  digitalWrite(LED_BUILTIN, isNearby);

  if(isNearby == true)
  {
    PORTC = 0b01111111;
    tone(A0, 262, 250);
  }
  else
  {
    PORTC = 0b10000000;
    noTone(buzzer);
  }

  lcd.print("Dist(cm)= ");
  lcd.setCursor(10,0);
  lcd.print(readDistanceCM());
  delay(1000);
  lcd.clear();
}