#define hall 2
#include <Wire.h>
#include <LCD.h>
#include <LiquidCrystal_I2C.h>

#define led 13
#define opseg 2*3.14592*0.2
#define I2C_ADDR    0x27 // <<----- Add your address here.  Find it from I2C Scanner
#define BACKLIGHT_PIN     3
#define En_pin  2
#define Rw_pin  1
#define Rs_pin  0
#define D4_pin  4
#define D5_pin  5
#define D6_pin  6
#define D7_pin  7

volatile unsigned long VrijemePadajuceg=0;
volatile unsigned long VrijemeRastuceg=0;
double rps=0;
double Brzina=0;
LiquidCrystal_I2C  lcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(hall,INPUT);
  lcd.begin (16,2);
  lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);
  lcd.setBacklight(HIGH);
  lcd.home ();
  //pinMode(led,OUTPUT);
  attachInterrupt(0,padajuci,FALLING);

}

void loop() {
  VrijemeRastuceg=millis();
  //rps=1.0/(millis()-VrijemePadajuceg);
  //rps*=1000;
  //if(rps<1) rps=0;
  Brzina=opseg/(((double)millis()-VrijemePadajuceg)/1000)*(3.6);
  //Serial.print(rps);
  //Serial.println(" rps");
  Serial.print("Vrijeme padajuceg briga:");
  Serial.println(VrijemePadajuceg);
  Serial.print("Vrijeme rastuceg briga:");
  Serial.println(VrijemeRastuceg);

  lcd.setCursor(0,0);
  lcd.print("Brzina:");
  lcd.setCursor(0,1);
  lcd.print(Brzina);
  lcd.print(" km/h  ");
  delay(500);
  }

void padajuci()
{
  //Serial.println("Magnet detected");
  VrijemePadajuceg=millis();
}