void setup()
{
  // put your setup code here, to run once:
  //Rows are connected to PORTL and columns are connected to PORTF
  volatile char *dirf = (char*)0x30;
  volatile char *dirl = (char*)0x10A;
  volatile char *outf = (char*)0x31;
  volatile char *outl = (char*)0x10B;

  *dirf = 0xFF;
  *dirl = 0xFF;

  char  count = 0;
  volatile int a = 0, i = 0, j = 0;

  //LED display pattern
  volatile int dot[2] = {0xAA, 0x55};
  //0b10101010
  //0b01010101
  while (1)
  {
    for (i = 0; i < 8 ; i++)
    {
      for (a = 0; a < 10000; a++)
      {
        for (j = 0; j < 2; j++)
        {
          *outl = ~(1 << i);
          //*outf = dot[i];
          *outf = dot[i + j];
          *outl = 0xFF;
          *outf = 0;
        }
      }
    }
    delay(100);
  }
}