【温故而知新】【2】时钟分频-奇数50%占空比

56 阅读 0 评论 37 点赞

我是靠谱客的博主平常河马，最近开发中收集的这篇文章主要介绍【温故而知新】【2】时钟分频-奇数50%占空比，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

【温故而知新】【2】时钟分频-奇数50%占空比

昨天写了个时钟分频的Verilog代码，今天继续写，只不过这次写的是：奇数分频，50%占空比
实现方法很简单：

计数器，时钟正边沿计数
上升沿触发的时钟分频
下降沿触发的时钟分频
合并上述两种时钟分频信号

Verilog代码如下，依然是参数化的设计：

这里写代码片

//===========================================================
// Author: seuchenrui@126.com
//
// Description:
// This is a simple verilog code for clock frequency division
// this code can be used to get 
// 1. odd integer division (duty = 50%)
//===========================================================

module clock_div_odd_50
#(parameter DIV_NUMBER=31)
(
    input   iCLK,
    input   iRESET,
    output  oCLK
);

reg [clogb2(DIV_NUMBER)-1:0] count;
reg tPCLK;
reg tNCLK;

always@(posedge iCLK or negedge iRESET)
begin
    if(!iRESET)
        count <= 'd0;
    else if(count == DIV_NUMBER -1)
        count <= 'd0;
    else
        count <= count + 1'b1;
    end

always@(posedge iCLK or negedge iRESET)
begin
    if(!iRESET)
        tPCLK <= 1'b0;
    else if(count == (DIV_NUMBER+1)/2-1)
        tPCLK <= ~tPCLK;
    else if(count == DIV_NUMBER -1)
        tPCLK <= ~tPCLK;
    else
        tPCLK <= tPCLK;
end
always@(negedge iCLK or negedge iRESET)
begin
    if(!iRESET)
        tNCLK <= 1'b0;
    else if(count == (DIV_NUMBER+1)/2-1)
        tNCLK <= ~tNCLK;
    else if(count == DIV_NUMBER -1)
        tNCLK <= ~tNCLK;
    else
        tNCLK <= tNCLK;
end

assign oCLK = tPCLK | tNCLK;
//================================
// this function is used to check 
// bitwidth of the data
//================================
function integer clogb2;
input [31:0] depth;
    begin
        for(clogb2 = 0; depth>0;clogb2=clogb2+1)
        depth = depth>>1;
    end
endfunction

endmodule