#include <LiquidCrystal.h>
#include<NewPing.h>

LiquidCrystal lcd(1, 2, 4, 5, 6, 7);
const int contrast = 55;

const int RED_LED = 10;
const int BUZZER = 11;

const int TRIGGER = 12;
const int ECHO = 13;

const int MAX_DISTANCE = 30; // centimetres;
const int ALARM_DISTANCE = 5; // centimetres;

NewPing sonar(TRIGGER, ECHO, MAX_DISTANCE);

void setup() {
  // put your setup code here, to run once:
  // Serial.begin(9600);
  pinMode(RED_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);


  analogWrite(9, contrast);
  lcd.begin(16, 2);
}

void loop() {
  // put your main code here, to run repeatedly:
  int distance = sonar.ping_cm();
  
  lcd.clear();

  if (distance == 0) {
    distance = sonar.ping_cm();
    digitalWrite(RED_LED, LOW);
    digitalWrite(BUZZER, LOW);
    lcd.print("No Obstructions");
  } else {
    if (distance <= ALARM_DISTANCE) {
      //  too close. sound alarm;
      digitalWrite(RED_LED, HIGH);
      digitalWrite(BUZZER, HIGH);
      lcd.setCursor(0, 1);
      lcd.print("TOO CLOSE");
    } else {
      lcd.print(distance);
      lcd.print(" cm");
      digitalWrite(RED_LED, LOW);
      digitalWrite(BUZZER, LOW);
    }
  }

  delay(250);
}