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ECE 275 - Sequential Logic Systems
Fall 2020 - Lab 9
Note is prelab due when you come to lab - there will be no time to work on it in lab

In this lab you will do a complete sequential circuit design. You are to design a Mealy sequential network with input X and output Z Your circuit will produce an output of  Z = 1 for any input sequence ending in 0101, provided that the sequence 110 has occurred at least once.  For example

 X = 1 0 1 0 1 0 1 1 0 1 0 1 0 1 1 0 1 0 1 Z = 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 1

Notice that the circuit does not reset to the start state when an output of  Z = 1 occurs.  Your circuit should, however, have a start (reset) state and a reset input.  Other requirements:

·         Do a state diagram and state table.

·         Use an implication table to reduce the number of states or verify that the number of states can not be reduced.

·         Make a state assignment using the three guidelines.  Assign 000 to the start state.

·         Design your network using NAND gates, NOR gates, and J-K flip-flops. Your solution must use 9 or fewer gates and inverters (the best known solution uses 4).

·         Simulate your design. Use the above sequence, as it will exercise your whole state table.

·         Connect your flip-flop outputs to LEDs for observation during testing.

·         Download your design to the prototyping board and have it checked by the instructor or teaching assistant.

Come to lab with your complete design including state diagram, state table, implication table, use of guidelines for state assignment, k-maps, and a drawing of your circuit. This prelab (what you have done when you come in) will be a significant part of the grade.

Notes:

·         You can use a pushbutton for your clock input. Wire this up yourself to some pin.

·         You will need to debounce your push button input.

·         A global reset is provided which you can use. It must be assigned in the circuit design in such a way as to reset the circuit state.

·         As mentioned above, connect your flip-flop outputs to some LEDs. This way you can witness each state change to make sure your circuit is performing properly.

·         Double check your wiring in the BDF file and make sure everything is really connected. (Drag around a gate and see if the wires move with it.)