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

LiquidCrystal_I2C lcd(0x27, 16, 2);

long duration;
float distance;

int T = 9;
int E = 10;
int L = 13;
int B = 11;
int S;

bool running = false;
unsigned long startTime;
unsigned long stopTime;

void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("ms: ");
  pinMode(B, INPUT);
  pinMode(T, OUTPUT);
  pinMode(E, INPUT);
  pinMode(L, OUTPUT);
}

void loop() {
  S = digitalRead(B);

  if (S == HIGH && !running) {
    running = true;
    startTime = millis();
    Serial.println("Timer gestartet!");
  }

  digitalWrite(T, LOW);
  delayMicroseconds(2);
  digitalWrite(T, HIGH);
  delayMicroseconds(10);
  digitalWrite(T, LOW);

  duration = pulseIn(E, HIGH);
  distance = duration * 0.034 / 2;

  if (running && distance <= 1.0) {
    stopTime = millis();
    running = false;
    unsigned long elapsedTime = stopTime - startTime;
    Serial.print("Timer gestoppt! Zeit: ");
    Serial.print(elapsedTime);
    Serial.println(" ms");
  }

  Serial.print("Distanz: ");
  Serial.print(distance);
  Serial.println(" cm");

  lcd.setCursor(1, 0);
  lcd.print(distance);

  delay(200);
}