void setup() {
  // put your setup code here, to run once:
  volatile char *ddra,*outa,temp;
  volatile long i,j;
  ddra=0x21;outa=0x22;
  *ddra=0xff;
  while(1){
    temp=0x00;
    for(j=0;j<8;j++)
    {
      *outa=(1<<j)+temp;
      temp=*outa;
      for(i=0;i<400000;i++);
      *outa=0x00;
      for(i=0;i<400000;i++);
    }
  }
}