1. step: CtrB: X0XX XXXX
         CtrA: X0XX XXXX

2. step: CtrB: X1XX XXXX
         CtrA: X0XX XXXX

3. step: CtrB: X0XX XXXX
         CtrA: X1XX XXXX

4. step: CtrB: X1XX XXXX
         CtrA: X1XX XXXX