velocímetro con arduino, sensor de efecto hall y pantalla lcd con i2c

//Include libraries
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

//Define constants
#define PIN_SENSOR A0
#define MAX_VALUE 255
#define MAX_SPEED 100 //m/s
#define MAX_DISTANCE 10 //m

//Define objects
LiquidCrystal_I2C lcd(0x27, 20, 4);

//Define variables
int sensorValue;
float speed;
float distance;

//Setup function
void setup() {
  lcd.init();
  lcd.clear();
  lcd.backlight();
  lcd.begin(20, 4);
  lcd.setCursor(0, 0);
  lcd.print("  Velocimetro");
  lcd.setCursor(0, 1);
  lcd.print("  con Arduino");
  lcd.setCursor(0, 2);
  lcd.print("  y sensor de");
  lcd.setCursor(0, 3);
  l