小梅哥课程学习——LED花式玩法（从计数器器到线性序列机）——实验一

//让LED按照量0.25秒，灭0.75秒的循环亮灭。
原代码
module counter_led_1(
    clk,
    reset_n,
    led
);
    input clk;
    input reset_n;
    output reg led;
    parameter MCNT=50000000;
    reg [25:0] counter;
    always@(posedge clk or negedge reset_n)
        if(!reset_n)
            counter<=0;
        else if(counter==MCNT-1)
            counter<=0;
        else
            counter<=counter+1'b1;
    always@(posedge clk or negedge reset_n)
        if(!reset_n)
            led<=0;
        else if(counter==(MCNT/2+MCNT/4)-1)
            led<=1;
        else if(counter==MCNT-1)
            led<=0;
endmodule
仿真代码
`timescale 1ns/1ns
module counter_led_1_tb();
    reg clk;
    reg reset_n;
    wire led;
    defparam counter_led_1_inst0.MCNT=50000;
    counter_led_1 counter_led_1_inst0(
    .clk(clk),
    .reset_n(reset_n),
    .led(led)
    );
    initial clk=1;
    always #10 clk=!clk;
    
    initial begin
    reset_n=0;
    #201;
    reset_n=1;
    #2000000000;
    $stop;
    end

endmodule