打开电脑的计数器，输入计算值，可以得到计数值的十六进制为17D_7840.

由于最高位为1，用一个二进制位1表示即可，其他六位十六进制用四个二进制位表示。

位宽=1+6*4=25（位宽等于：最高位的二进制位数+剩余的位数*4）

module counter_led

(

clk50M,

rst_n,

led

);

input clk50M;   //the frequence system clock

input rst_n;    //global reset,active low level

output led;     //the output IO/port

parameter T500Ms = 25'd24_999_999;

reg [24:0]cnt;  //the shortening of counter,define the counter register

//the counting process of 500Ms counter

always@(posedge clk50M or negedge rst_n)

if(!rst_n)

cnt<=25'd0;

else if(cnt==T500Ms)

cnt<=25'd0;

else

cnt<=cnt+1'b1;

//  the concrl of the output port of led

reg rled;

always@(posedge clk50M or negedge rst_n)

if(!rst_n)

rled<=1'b1;

else if(cnt==T500Ms)

rled<=~rled;

else

rled<=rled;

assign led = rled;

endmodule

//设计的Testbench文件：

`timescale 1ns/1ns

module counter_led_tb;

reg clk;

reg rst;

wire rled;

counter_led counter_led_m0

(

.clk50M(clk),

.rst_n(rst),

.led(rled)

);

initial clk=1;

always begin

#10 clk=~clk;

end

initial begin

rst=0;#2000;

rst=1;#200000;

rst=0;#500_000_000;

rst=1;#600_000_000;

$stop;

end

endmodule

仿真波形如下：

仿真波形正确，led在1000Ms时翻转一次，实现了功能。