Here is a minimal common code for Ping-Pong Game for Arduino - part 1/3

_28_arduSerie_pong_game_00.ino

int n;                       // display row counter

void setup() {
  for (int z = 2; z < 14; z++) {
    pinMode(z, OUTPUT);     // all pins output for driving the LED matrix
  }

  //digitalWrite(5, HIGH);     // all pins output for driving the LED matrix
  //digitalWrite(12, HIGH);     // all pins output for driving the LED matrix

  // intitialize interrupt timer 2
  TCCR2A = 0;               // TC2 Control Register A - no ocr or pwm ; normal operation
  TCCR2B = 4;               // TC2 Control Register b - Clock Select Bit 1<<CS22 | 0<<CS21 | 0<<CS20 //prescale 1:64
  TIMSK2 = 1 << TOIE2;      // TC2 Interrupt Mask Register - TOIE2: Timer/Counter2, Overflow Interrupt Enabled
  TCNT2 = 0x06;             // The counter value (TCNT2) are initialize in 6 decimal; see calculations below:
}

void loop() {

  //delay(10000);
}

ISR(TIMER2_OVF_vect) {      // Interrupt Routine:
  TCNT2 = 0x06;
  PORTD &= 0xE3;            // clear PIN 2,3,4
  PORTD |= (n << 2) & 0x1C; // set collumn trough the mux, see:
  n++;                      // increase collumn counter
  if (n > 7) {              // count from 0 to 7
    n = 0;                  // next image. Refreshrate = 1000/8 images/sec = 125Hz (8 x ISR)
  }
}