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

LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE);


unsigned long aktMillis, altMillis, Imp;
const unsigned int torzeit = 1000;
bool aktStatus, altStatus;

void setup() {
  lcd.begin(20,4);
  pinMode(2, INPUT); //Pin 2
  pinMode(13, OUTPUT);
  aktStatus = digitalRead(2);
  altStatus = aktStatus;
}

void loop() {
  aktMillis = millis();
  aktStatus = digitalRead(2);
  if (altStatus && !aktStatus) Imp++;
  altStatus = aktStatus;
  if (aktMillis - altMillis >= torzeit) {
    altMillis = aktMillis;
    lcd.setCursor(0,0);
    lcd.print("Impulse = ");
    lcd.print(Imp); lcd.println(" Imp/s    ");
    Imp = 0;
  }

// ab hier stimmt was nicht:

  float z;
  z= Imp *7.5 / 60;
  lcd.setCursor(0,2);
  lcd.print(z,2);
  }