27. LED Toggle on Rising Edge

module led_toggle (
    input  clk,
    output reg led
);
    initial led = 1'b0;

    always @(posedge clk) begin
        led <= ~led;  // toggle at each rising edge
    end
endmodule

💡Remember

• always @(posedge clk) describes logic that updates once per rising clock edge.
• Outputs driven inside such a block remember their value from one edge to the next.
• Using <= (non-blocking) ensures all sequential updates happen in parallel at each clock.
• Here, the LED simply toggles (0→1→0→1...) every clock cycle, because we assign led <= ~led;.
• In hardware terms this becomes a 1-bit storage element, but you can just think:
  “on each clock tick, update LED to the opposite of its current value.”