#include <SPI.h> // import SPI library

#define LATCH_PIN  27   // RCLK (ST_CP)
#define BUTTON_INC  34 // Increase count
#define BUTTON_DEC  35  // Decrease count

// ===== Digit patterns (Common Cathode) ====
byte digits[10] = 
{
  0b00111111, // 0
  0b00000110, // 1
  0b01011011, // 2
  0b01001111, // 3
  0b01100110, // 4
  0b01101101, // 5
  0b01111101, // 6
  0b00000111, // 7
  0b01111111, // 8
  0b01101111  // 9
};

//======= specific syntax for interupt========
volatile bool BTN_INC = false; //check if score increase button is pressed
volatile bool BTN_DEC = false; //check if score decrease button is pressed

int LeftDigit = 0;
int RightDigit = 0;

void IRAM_ATTR INC_ISR() // interupt function for score increase
{
  BTN_INC = true; 
}

void IRAM_ATTR DEC_ISR() // interupt function for score decrease
{
  BTN_DEC = true; 
}


void setup() 
{
  pinMode(LATCH_PIN, OUTPUT);
  pinMode(BUTTON_INC, INPUT_PULLUP);
  pinMode(BUTTON_DEC, INPUT_PULLUP);
 
  SPI.begin();

  digitalWrite(LATCH_PIN, HIGH);

  attachInterrupt(digitalPinToInterrupt(BUTTON_INC),INC_ISR,FALLING);
  attachInterrupt(digitalPinToInterrupt(BUTTON_DEC),DEC_ISR,FALLING);
}

void loop() 
{
  delay(2000);
  LeftDigit++;

  if(LeftDigit > 9)
  { 
    LeftDigit = 0;
  }


  if(BTN_INC)
  {
    BTN_INC = false;
    RightDigit++;

    if(RightDigit > 9)
    {
      RightDigit = 0;
    }

  }
  
   if(BTN_DEC)
  {
    BTN_DEC = false;
    RightDigit--;

    if(RightDigit < 0)
    {
      RightDigit = 9;
    }

  }
 
  digitalWrite(LATCH_PIN,LOW);

  SPI.transfer(digits[RightDigit]);
  SPI.transfer(digits[LeftDigit]);

  digitalWrite(LATCH_PIN,HIGH);



}