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Explanation of Key Sections in the Code

To ensure that the reader can understand and modify the TestBench if needed, let's go through the main parts of the code:

D_FLIP_FLOP FF1 (.D(b0), .sync_reset(Reset), .Q(Q1));

D_FLIP_FLOP FF2 (.D(Q1), .sync_reset(Reset), .Q(Q2));

D_FLIP_FLOP FF3 (.D(Q2), .sync_reset(Reset), .Q(led0));

  • Three Flip-Flops are instantiated and connected in cascade.

  • The first Flip-Flop receives the input signal b0, and each subsequent Flip-Flop takes the Q output of the previous one as input.

  • The last output (led0) represents the divided frequency after three Flip-Flop stages.

always #5 b0 = ~b0;  // Toggle b0 every 5 time units (creates clock signal)

  • This command toggles b0 every 5 time units, effectively simulating a 10-time unit period clock.

  • As a result, b0 acts as a square wave signal.

initial begin

  Reset = 1;

  b0 = 0;

  #10 Reset = 0; // Release reset

end

  • The Reset signal is initially set to 1 to clear all Flip-Flop outputs.

  • After 10 time units, Reset is set to 0, allowing normal operation of the Flip-Flops.


initial begin

  $dumpfile("testbench.vcd");

  $dumpvars(0, testbench);

  #1000 $finish; // Run the simulation for sufficient time

end

  • The $dumpfile("testbench.vcd") command stores all simulation data in a .vcd file for waveform analysis.

  • The simulation runs for 1000 time units, ensuring enough time to observe multiple frequency divisions.