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

LiquidCrystal_I2C lcd(0x27,16,2);  // set the LCD address to 0x27 for a 16 chars and 2 line display

volatile boolean controle = false;
volatile uint16_t tempo = 0;

void inicioContador(){
  controle = true;
}

void fimContador(){
  controle = false;
}
// This function will be called every time TIMER2 overflows
// and it is binded to Timer2 Overflow Interrupt Service Routine
ISR(TIMER2_OVF_vect) {
    // as Arduino integers are only 16 bits but we will need to
    // count the overflows until 312500 to get 5 seconds, so
    // we will use two variables for that and control them as
    // we need
    static uint16_t overflow_count = 0;
    static uint16_t segundos = 0;

    if (controle){
      overflow_count ++;
      tempo = overflow_count * 16.384e-3 * 1000;
    }


}

void setup() {
    Serial.begin(9600);
    lcd.init();
    lcd.backlight();
    
    // // Set pin 13 as output
    // pinMode(13, OUTPUT);
    // Set pin 2 as input
    pinMode(2, INPUT);
    pinMode(3, INPUT);

    // Attach interrupt to pin 2 through specifc function
    // attachInterrupt that can only be used with Arduino
    // pins that are interrupt capable (2 and 3 on the Uno)
    attachInterrupt(
        digitalPinToInterrupt(2), inicioContador, FALLING
    );
    attachInterrupt(
        digitalPinToInterrupt(3), fimContador, FALLING
    );

    // Set TIMER2 to normal mode
    // Arduino UNO has two controller registers for TIMER2: TCCR2A and TCCR2B
    TCCR2A = 0b00000000; // normal operation mode
    TCCR2B = 0b00000111; // /8 prescaler
    // Enable TIMER2 overflow interrupt (not studied yet, but we need to enable
    // it in order to see `FOC0` bit behavior). When we enable it it will be
    // binded to a ISR function that we need to implement in our code
    // As Timer0 can only count to 255 we need to count the times it overflows
    // So we will build it in our ISR function
    TIMSK2 = TIMSK2 | 0b00000001;
    
}

void loop() {
    // we'll handle the button press outside the ISR in order to
    // avoid blocking the ISR
    lcd.setCursor(3, 1);
    lcd.print(tempo);
    
}