Digital Taxi Fare Meter using Arduino

#include "TimerOne.h"                      //Include Timer1 library for using Timer1 functions
#include <LiquidCrystal.h>                 //Include LCD library for using LCD display functions     

const int rs = 12, en = 13, d4 = 8, d5 = 9, d6 = 10, d7 = 11;   //Define the LCD pins 
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);                      

volatile unsigned int counter=0;          
volatile unsigned int rotation=0;          
float rotationinm=0;
unsigned int speed=0;

void count()  // ISR for counts from the speed sensor
{
  counter++;  //increase the counter value by one
  rotation++; //Increase the rotation value by one
  delay(10); 
} 

void timerIsr()
{
 detachInterrupt(digitalPinToInterrupt(2));          //Stops the interrupt pin 2
 Timer1.detachInterrupt();                           //Stops the timer1 interrupt

 lcd.clear();          
 
 float speed = (counter / 20.0)* 60.0;              //Calcukate speed in minute (20-No of slots in Encoder Wheel)
 float rotations = 230*( rotation / 20);            //Calculate distance in cm (230-Circumference of the wheel assumed 20- No of slots)
 rotationinm = rotations/100;

 lcd.setCursor(0,0);
 lcd.print("Dist(m):");
 lcd.print(rotationinm);                            //Display rotationinm at LCD
 lcd.setCursor(0,1);
 lcd.print("Speed(RPM):");                       
 lcd.print(speed);                                  //Dsiplay speed in RPM
 
  counter=0;                                        //Reset counter to 0 

  int analogip = analogRead(A0);                   // Analog read from pin A0
  int motorspeed = map(analogip,0,1023,0,255);     //convert digital vales 0-1023 to 0-255
  analogWrite(5,motorspeed);                      //Sets PWM value at pin 5 
 
 Timer1.attachInterrupt( timerIsr );                        //Starts timer1 again
 attachInterrupt(digitalPinToInterrupt(2), count, RISING);  //Attaches interrupt at pin2 again
}

void generatefare()                           //ISR to generate the fareamount
{
   detachInterrupt(digitalPinToInterrupt(2)); //Disables the Interrupt pin at 2
   Timer1.detachInterrupt();                  //Disables the Timer1 interrupt
   float rupees = rotationinm*5;              //Muliply 5 with distance travelled (Rs 5 per meter )
   lcd.clear();                               //Clears LCD
   lcd.setCursor(0,0);
   lcd.print("FARE Rs: ");       
   lcd.print(rupees);                        //Display fare amount 
   lcd.setCursor(0,1);
   lcd.print("Rs 5 per metre");
}

void setup() 
{
  pinMode(A0,INPUT);                 //Sets pin A0 as INPUT 
  pinMode(5,OUTPUT);                 //Sets pin 5 as OUTPUT 
  
  lcd.begin(16,2);                   //Sets LCD as 16x2 type
  lcd.setCursor(0,0);                //The following code displays welcome messages
  lcd.print("CIRCUIT DIGEST");
  lcd.setCursor(0,1);
  lcd.print("WELCOME TO TAXI");
  delay(3000);
  lcd.clear();
  lcd.print("LETS START :)");
  delay(1000);
  lcd.clear();

  Timer1.initialize(1000000);          //Initilize timer1 for 1 second 
  Timer1.attachInterrupt( timerIsr );  //ISR routine to be called for every one second
  
  attachInterrupt(digitalPinToInterrupt(2), count, RISING);     // Pin 2 as Interrupt pin with count ISR is called when LOW to RIGH happens.
  attachInterrupt(digitalPinToInterrupt(3), generatefare, HIGH); //Pin 3 as Interrupt pin with generatefare ISR is called when HIGH is detected.