10 second counter
As detailed in the Project Guide, the user is to input a 4-bit binary code during a 10 second ‘window’, whereby a correct input code within this time frame will open the lock. ... Therefore, the objective was to design a counter that will count in a sequence for 10 intervals, with each interval being 1 second. ... Consequently, 10 + 1 states were required. On the 11th state, the output from the counter was used as a trigger to: 1.