#include <LiquidCrystal.h>

float n1;
float n2;
char op;
float res = 0.0;

int rs = 7;
int en = 4;
int d4 = 9;
int d5 = 10;
int d6 = 11;
int d7 = 12;

const int echoPin = A0;
const int trigPin = A1;

LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

void setup() {
  lcd.begin(16, 2);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  Serial.begin(9600);
}

void loop() {
  float distance = getDistance();

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("DISTANCIA:");
  lcd.setCursor(0, 1);
  lcd.print(distance);
  lcd.print(" cm");

  if (distance < 10.0) {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Alarma:");
    lcd.setCursor(0, 1);
    lcd.print("Estas a < 10 cm");
  }

  delay(1000);
}

float getDistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  float duration = pulseIn(echoPin, HIGH);

  float distance = (duration * 0.0343) / 2;

  return distance;
}