17.分频器设计拓展练习-任意分频通用模块

(1)Verilog代码：

module divider_n(clk,reset_n,clk_out);
    
    input clk;
    input reset_n;
    output clk_out;

    wire clk_out1;
    wire clk_out2;
    
    wire [9:0]n;
    wire m;
    
    assign n = 9;
    assign m = n % 2;
    
    divider_even divider_even_inst(
        .clk(clk),
        .reset_n(reset_n),
        .n(n),
        .en(!m),
        .clk_out(clk_out1)
    );
    
    divider_odd divider_odd_inst(
        .clk(clk),
        .reset_n(reset_n),
        .n(n),
        .en(m),
        .clk_out(clk_out2)
    );
    
    assign clk_out = m ? clk_out2 : clk_out1;

endmodule

module divider_even(clk,reset_n,n,en,clk_out);

    input clk;
    input reset_n;
    input [9:0]n;       //分频数
    input en;
    
    output reg clk_out;
    
    reg [9:0]cnt;
    
    wire [9:0]MCNT;
    
    assign MCNT = (n >> 1) - 10'd1;

//计数器模块设计   
    always@(posedge clk or negedge reset_n)
        if(!reset_n)
            cnt <= 10'd0;
        else if ((cnt == MCNT)&&(en))
            cnt <= 10'd0;
        else if(en)  
            cnt <= cnt + 10'd1;
        else 
            cnt <= 10'd0;

//clk_out信号设计
    always@(posedge clk or negedge reset_n)
        if(!reset_n)
            clk_out <= 1'd0;
        else if (cnt == MCNT)
            clk_out <= ~clk_out;
        else 
            clk_out <= clk_out;
            

endmodule

module divider_odd(clk,reset_n,n,en,clk_out);

    input clk;
    input reset_n;
    input [9:0]n;     //分频数
    input en;
    
    output clk_out;
    
    reg [9:0]cnt;
    reg clk_1;
    reg clk_2;
    
    wire [9:0]MCNT;
    wire [9:0]Mid;
    
    assign MCNT = n - 10'd1;
    assign Mid  = (n >> 1);
 
//计数器模块设计
    always@(posedge clk or negedge reset_n)
        if(!reset_n)
            cnt <= 10'd0;
        else if((cnt == MCNT)&&(en))
            cnt <= 10'd0;
        else if(en)
            cnt <= cnt + 10'd1;
        else 
            cnt <= 10'd0;
            
//clk_1信号设计
    always@(posedge clk or negedge reset_n)
        if(!reset_n)
            clk_1 <= 1'd0;
        else if(cnt == Mid)
            clk_1 <= 1'd1;
        else if(cnt == MCNT)
            clk_1 <= 1'd0;
        else 
            clk_1 <= clk_1;

//clk_2信号设计
    always@(negedge clk or negedge reset_n)
        if(!reset_n)
            clk_2 <= 1'd0;
        else if(cnt == Mid)
            clk_2 <= 1'd1;
        else if(cnt == MCNT)
            clk_2 <= 1'd0;
        else 
            clk_2 <= clk_2;

    assign clk_out = (clk_1 | clk_2);

endmodule

（2）代码层次：

（3）仿真代码：

`timescale 1ns / 1ps

module divider_n_tb;

    reg clk;
    reg reset_n;
    
    wire clk_out;

    divider_n divider_n_inst(
        .clk(clk),
        .reset_n(reset_n),
        .clk_out(clk_out)
    );
    
    initial clk = 1'd1;
    always #10 clk = ~clk;
    
    initial begin
        reset_n = 1'd0;
        #15;
        reset_n = 1'd1;
        #2000
        $stop;
    end

endmodule

（4）仿真波形

（5）将顶层模块的n改成10，重新进行仿真

（6）引脚绑定：

（7）以下分别是n=10和n=25时的示波器实验现象，时钟频率为50MHz