小梅哥课程学习——LED花式玩法（从计数器器到线性序列机）——实验二

//让LED灯按照亮0.25秒，灭0.5秒，亮0.75秒，灭1秒的状态循环亮灭。
源代码
module counter_led_2(
    clk,
    reset_n,
    led
);
    input clk;
    input reset_n;
    output reg led;
    parameter MCNT=125000000;
    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<=1;
        else if(counter==(MCNT/10)-1)
            led<=0;
        else if(counter==(MCNT/10+MCNT/5)-1)
            led<=1;
        else if(counter==(MCNT/10+MCNT/5)*2-1)
            led<=0;
        else if(counter==MCNT-1)
            led<=1;
endmodule
仿真代码
`timescale 1ns/1ns
module counter_led_2_tb();
    reg clk;
    reg reset_n;
    wire led;
    defparam counter_led_2_inst0.MCNT=125000;
    counter_led_2 counter_led_2_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