// LCD1602 to Arduino Uno connection example

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

#define TRIG 10
#define ECHO 11

long distance, pulse_duration;

void setup() {
  Serial.begin (9600);
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  lcd.init();
  lcd.backlight();
}

void clearScreen(int line)
{
  //delay(200);
  lcd.setCursor(0, line);
  for (int i = 0; i < 12; i++)
  {
    lcd.setCursor(i, line);
    lcd.print(" ");
  }
}

void loop() {

  clearScreen(0);
  clearScreen(1);

  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);
 
  pulse_duration = pulseIn(ECHO, HIGH);

  distance = round(pulse_duration * 0.0171);

  lcd.setCursor(0, 0);
  lcd.print(distance);
  
  if (distance < 20)
  {
    lcd.setCursor(0, 1);
    lcd.print("Danger");
  } else {
    lcd.setCursor(0, 1);
    lcd.print("Safe");
  }

  delay(100);
}