Velocimetro

#include <LiquidCrystal.h>
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);

//#include <LiquidCrystal_I2C.h>                                        // Biblioteca LCD I2C
//LiquidCrystal_I2C lcd(0x38,  2, 1, 0, 7, 6, 5, 4, 3, POSITIVE);       // Set the LCD I2C address

unsigned long temp;
unsigned long temp1;
float vel;
const int buttonPin1 = 2;
const int buttonPin2 = 3;                       //pino 3
const int ledPin = 13;                          // pino 13 led
int buttonState1 = 0;
int buttonState2 = 0;
unsigned long tempo;
//------------------------------------------
void setup()
{
  lcd.begin(16, 2);
  pinMode(ledPin, OUTPUT);                            // led saida
  pinMode(buttonPin1, INPUT_PULLUP);                   // pino2, sensor 1
  pinMode(buttonPin2, INPUT_PULLUP);                   // sensor 2

  Serial.begin(9600);
  vel = 0;
  temp = 0;
  temp1 = 0;
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Temp = ");
  lcd.setCursor(0, 1);
  lcd.print("Veloc= ");
}
//-----------------------------------
void loop()
{

  buttonState1 = digitalRead(buttonPin1);
  buttonState2 = digitalRead(buttonPin2);
  if (buttonState1 == LOW)                      // se o botao 1 estiver activado
  {
    digitalWrite(ledPin, HIGH);
    temp = millis();
  }
  if (buttonState2 == LOW)
  {
    temp1 = millis() - temp;
    lcd.setCursor(7, 0);
    lcd.print(temp1/1000);
    lcd.print("     ");
    lcd.setCursor(7, 1);
    vel = 30000 / (temp1 );
    lcd.print(vel,0);
    lcd.print(" m/seg     ");
  }
}