#include <U8g2lib.h>
#include <Wire.h>

U8G2_SSD1306_128X64_NONAME_1_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE);
volatile boolean flag;

void attachInterrupt_fun_FALLING_2() {
  flag = true;
}

void setup(){
  u8g2.setI2CAddress(0x3C*2);
  u8g2.begin();
  flag = false;
  pinMode(2, INPUT_PULLUP);
  pinMode(2, INPUT_PULLUP);
}

void loop(){
  attachInterrupt(digitalPinToInterrupt(2),attachInterrupt_fun_FALLING_2,FALLING);

  if (flag) {
    u8g2.firstPage();
    do
    {
      u8g2.drawDisc(60,30,10,U8G2_DRAW_ALL);
    }while(u8g2.nextPage());

  }

}