#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C mylcd(0x27,16,2);
volatile int distance;

float checkdistance_2_3() {
  digitalWrite(2, LOW);
  delayMicroseconds(2);
  digitalWrite(2, HIGH);
  delayMicroseconds(10);
  digitalWrite(2, LOW);
  float distance = pulseIn(3, HIGH) / 58.00;
  delay(10);
  return distance;
}

void setup(){
  pinMode(2, OUTPUT);
  pinMode(3, INPUT);
  pinMode(1, OUTPUT);
  pinMode(7, OUTPUT);
  mylcd.init();
  mylcd.backlight();
  distance = 0;
}

void loop(){
  distance = checkdistance_2_3();
  mylcd.setCursor(1-1, 1-1);
  mylcd.print(String("distance:") + String(String(distance) + String("cm")));
  if (0 < distance && distance < 20) {
    mylcd.setCursor(1-1, 2-1);
    mylcd.print("STOP NOW!");
    digitalWrite(1,HIGH);
    tone(7,587);
    delay(1000);

  } else if (20 <= distance && distance < 40) {
    mylcd.setCursor(1-1, 2-1);
    mylcd.print("ATTENTION");
    digitalWrite(1,LOW);
    tone(7,587);
    delay(50);
    digitalWrite(1,HIGH);
    noTone(7);
    delay(50);
  } else if (40 <= distance && distance < 60) {
    mylcd.setCursor(1-1, 2-1);
    mylcd.print("TAKE A LOOK");
    digitalWrite(1,LOW);
    tone(7,587);
    delay(200);
    digitalWrite(1,HIGH);
    noTone(7);
    delay(200);
  } else {
    digitalWrite(1,LOW);
    mylcd.setCursor(1-1, 2-1);
    mylcd.print("REST ASSURED");

  }

}