Untitled Circuit (2)

Set the simulation time to a suitable value, such as 100ms. Run the simulation. To operate the lock in the simulation, we can follow these steps: Momentarily activate the RESET switch. Set the switches SWA, SWB, and SWC to the first part of the combination. Momentarily toggle the ENTER switch back and forth. Set the switches to the second part of the combination. Toggle the ENTER switch again. If the correct combination is entered, the LED will turn on. Otherwise, the LED will remain off. Here is an example of a PSpice simulation of the circuit: * Simulation of sequential combination lock circuit * Components D flip-flops: U1, U2, and U3 Switches: SWA, SWB, and SWC Push-button switch: ENTER AND gate: U4 OR gate: U5 NOT gate: U6 LED: D1 * Subcircuit subckt combination_lock_subcircuit input SWA, SWB, SWC, ENTER output Q reg [2:0] state; always @(posedge ENTER) begin if (state == 3'b000) begin if (SWA == 1'b1 && SWB == 1'b1 && SWC == 1'b1) begin state <= 3'b001; end else begin state <= 3'b000; end end else if (state == 3'b001) begin if (SWA == 1'b0 && SWB == 1'b0 && SWC == 1'b0) begin Q <= 1'b1; end else begin state <= 3'b000; end end else begin state <= 3'b000; end end endsubckt * Circuit V1 5 0 DC 5V SWA 1 0 SW SWB 2 0 SW SWC 3 0 SW ENTER 4 0 SW U1 5 6 DFF U2 7 8 DFF U3 9 10 DFF U4 11 12 13 AND U5 14 15 16 OR U6 17 18 NOT D1 19 20 LED * Connections SWA 1 11 SWB 2 12 SWC 3 13 ENTER 4 15 U1.Q 6 17 U2.Q 8 14 U3.Q 1