Intro: Signal Won’t Toggle

You’re simulating a simple toggle flip-flop, but it’s not working — the output q stays at 0 forever.

Here’s the code:

module toggle_ff (
  input  logic clk,
  input  logic rst_n,
  output logic q
);

always_ff @(posedge clk or negedge rst_n) begin
  if (!rst_n)
    q <= 0;
  else if (clk)
    q <= ~q;
end

endmodule

❓ Your Challenge:

1. Why doesn’t q toggle as expected during simulation?
2. What would you change to fix the code?