State Diagram Implementation

Pre-initialized Components

The simulation workspace comes with the following components already placed:

• Input X: Binary input signal (left side)
• Clock: Clock signal for synchronizing state transitions (left side, below Input X)
• Output A: First output bit (right side, top)
• Output B: Second output bit (right side, bottom)

Components Required (to be added by user)

• JK flip-flops (as needed for state implementation)
• NOT gates
• AND gates
• OR gates
• XOR gates

Circuit Connections

Follow these steps to build the state machine circuit according to the provided state diagram:

1. Add JK Flip-Flops:

   • Click on the JK flip-flop component in the left panel to add flip-flops to the working area.
   • Drag and position the flip-flops in the central working area for easy connections.
   • You will need to determine the number of flip-flops based on the state diagram provided (typically 2 flip-flops for a 4-state machine).

2. Connect Clock Signal:

   • Connect the Clock signal (pre-placed on the left) to the CLK input of each JK flip-flop.
   • This ensures all state transitions occur synchronously on clock edges.
   • Drag from the Clock output endpoint to the CLK input endpoint of each flip-flop.

3. Add Logic Gates:

   • Click on the required logic gates (AND, OR, NOT, XOR) from the component panel to add them to the working area.
   • Position the gates strategically between the flip-flops and inputs/outputs for organized wiring.

4. Implement Next-State Logic:

   • Design the J and K inputs for each flip-flop according to the state diagram equations.
   • Connect Input X and flip-flop Q outputs to logic gates as needed.
   • Connect logic gate outputs to the J and K inputs of flip-flops to implement the next-state logic.
   • Example connections (adapt based on your state diagram):
     • For a simple design: Connect X and Q outputs through appropriate gates to control state transitions.

5. Connect Output Logic:

   • Connect the Q outputs of flip-flops to Output A and Output B (pre-placed on the right side).
   • You may need combinational logic gates between flip-flop outputs and the output bits depending on the state diagram.
   • Drag wires from flip-flop Q outputs to the output bit endpoints.

6. Delete Unwanted Components or Connections:

   • Right-click on any component or wire and select "Delete" to remove it.
   • This helps correct mistakes and refine your circuit.

7. Input String Configuration:

   • Click on the "Input" button to open the input string dialog.
   • Enter a binary input sequence for testing (e.g., "1011000010" to test various state transitions).
   • The input should contain only 0s and 1s.
   • Click "OK" to set the input string.

8. Simulation Execution:

   • Click on "Simulate" to run the circuit with the provided input string.
   • Observe how outputs A and B change as each input bit is processed sequentially.
   • The circuit will step through the input string, updating states on each clock cycle.

9. Circuit Verification:

   • Once you believe your circuit is correct, click on "Submit" to verify the implementation.
   • The system will test your circuit against predefined test cases.
   • If the circuit has been constructed correctly, a "Success" message will be displayed in the Observations section.
   • If incorrect, a "Fail" message will appear, and you should review your connections.

Observations

• The circuit implements a finite state machine with two output bits A and B that respond to the input stream X.
• The JK flip-flops store the current state, and the combinational logic determines the next state based on current state and input.
• Depending upon the input stream given, the states of outputs A and B will change according to the state diagram logic.
• The Clock signal ensures all state transitions occur synchronously on clock edges, maintaining proper timing relationships.
• For proper operation:
  • All flip-flops must be connected to the Clock signal.
  • The J and K inputs must implement the correct next-state logic from the state diagram.
  • Outputs A and B should be connected to the appropriate flip-flop Q outputs or combinational logic.
• The Observations section will display:
  • A state transition table showing how outputs A and B change for each input bit.
  • Success or Failure message after clicking Submit.
  • Any error messages if connections are missing or incorrect.
• Monitor the state transitions to verify your circuit behaves according to the given state diagram.

Key Design Considerations

• State Encoding: The binary values of outputs A and B represent different states of the finite state machine.
• Synchronous Operation: All state changes occur on clock edges for predictable behavior.
• Next-State Logic: The J and K inputs to flip-flops implement the state transition logic from the state diagram.
• Output Logic: Outputs A and B may be direct flip-flop outputs or require additional combinational logic.

Troubleshooting

• No state transitions: Check if Clock signal is properly connected to all flip-flops.
• Incorrect transitions: Verify J and K input connections match the state diagram equations.
• Simulation errors: Ensure all logic gates are properly connected with no dangling endpoints.
• Timing issues: Confirm only one Clock signal is used for all flip-flops to maintain synchronization.
• Input not working: Click "Input" button first and enter a valid binary string (only 0s and 1s) before clicking "Simulate".
• Submit fails: Double-check your circuit against the state diagram, ensuring all state transitions are correctly implemented.

Pattern Identifier - Alternate State Diagram

Components Required

• 3 JK flip-flops
• Combinational logic gates (AND, OR, NOT gates as needed)
• 1 Clock signal
• Input X (binary input stream)
• Outputs A and B (state outputs)

Circuit Connections

1. Initial Setup:

   • The circuit board comes with pre-placed Input X, Clock signal, and output bits A and B.
   • Drag three JK flip-flops from the component library to the working area.

2. Flip-Flop Connections:

   • Connect the Clock signal to the CLK input of all three JK flip-flops for synchronized operation.
   • Design and connect the J and K inputs for each flip-flop based on the alternative state diagram provided in the theory section.

3. Combinational Logic Implementation:

   • Add necessary NOT, AND, OR, and XOR gates to implement the next-state logic and output logic.
   • Connect logic gates according to the derived equations for the specific pattern being detected.

4. Output Connections:

   • Connect flip-flop Q outputs to output bits A and B as specified by the state diagram.
   • Add any additional combinational logic needed for the output function.

5. Input String Configuration:

   • Click on "Input" button to enter a test binary sequence.
   • Enter appropriate test patterns to verify the pattern detection behavior.

6. Simulation and Verification:

   • Click on "Simulate" to run the circuit with the input string.
   • Observe state transitions and output behavior in the Observations section.
   • Click on "Submit" to verify correct implementation.

Observations

• This circuit demonstrates an alternative state machine design for pattern identification.
• Follow the same systematic approach as the first task, adapting connections based on the specific state diagram.
• The Observations section will display state transitions and detection results.
• If the circuit is correctly implemented, a "Success" message will be displayed upon clicking "Submit".