void setup() {
  volatile char *dirf, *dirk, *dira, *dirc, *outf, *ink, *outa, *outc;
  dirf = 0x30; dirk = 0x107; dira = 0x21; dirc = 0x27;
  outf = 0x31; ink = 0x106; outa = 0x22; outc = 0x28;
  *dirf = 0x0F; *dirk = 0x00; *dira = 0x0F; *dirc = 0x0F;

  while(1){
    for(volatile char i=0;i<4;i++){
      *outf = (1<<i);
      *outa = *ink;
      if(*ink!=0){
        *outc = (1<<i);
        for(volatile long i=0;i<60000;i++);
        *outc = 0x00;
      }
    }
  }

}

void loop() {
  // put your main code here, to run repeatedly:

}