A little two-bit state machine decides which code is required to enter the next state. The fourth state equals to the lock being open. A wrong code in any state resets to the first state.
To test the project, refer to its Wokwi, which is public.
| # | Input | Output |
|---|---|---|
| 0 | unused | lock status |
| 1 | reset | unused |
| 2 | enter | unused |
| 3 | code digit 0 | unused |
| 4 | code digit 1 | unused |
| 5 | code digit 2 | unused |
| 6 | code digit 3 | unused |
| 7 | code digit 4 | unused |