VHDL分频

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我是靠谱客的博主务实苗条，最近开发中收集的这篇文章主要介绍VHDL分频，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

使用计数器实现n分频

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

entity div is
	port(n: in std_logic_vector(7 downto 0);
		clk: in std_logic;
		clkout: out std_logic);
end div;

architecture rtl of divvv is
	signal cnt: std_logic_vector(7 downto 0);
	signal n_t,n_1: std_logic_vector(7 downto 0);
begin
	n_1 <= n - 1;
	n_t <= '0' & n(7 downto 1);
	process(n, clk)
	begin 
		if clk'event and clk = '1' then 
			if cnt = n_1 then 
				cnt <= "00000000" ;
			else
				cnt <= cnt + 1;
			end if;
			if cnt < n_t then 
				clkout <= '0';
			else
				clkout <= '1';
			end if;
		end if;
	end process;
end rtl;

实现3.5分频

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY expp IS
PORT( clk: IN STD_LOGIC;
	  pout: out std_logic;
	  cont,cont1: buffer std_logic);
end expp;

architecture bhv of expp is
signal count: std_logic_vector(3 downto 0);
signal count1: std_logic_vector(3 downto 0);

begin

process(clk)

begin

if clk'event and clk = '1' then
	if count1 < 4 then 
		count1 <= count + 1; cont <= '0';
	else
		count1 <= "0000"; cont <= '1';
	end if;
end if;
end process;
process(clk) 
begin
if clk'event and clk = '0' then
	if count < 4 then  	
		count <= count1 + 1;  cont1 <= '0';
	else
		count <= "0000";  cont1 <= '1';
	end if;
end if;
end process;
pout <= cont and cont1;
end bhv;

完成一个9分频器，分频后的输出信号，其频率为输入信号的1/9，且输出信号占空比为1/2。

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY exp4 IS
PORT( clk: IN STD_LOGIC;
	  pout: out std_logic);
end exp4;

architecture bhv of exp4 is
signal count: std_logic_vector(3 downto 0);
signal count1: std_logic_vector(3 downto 0);
signal cont,cont1: std_logic;
begin

process(clk)

begin

if clk'event and clk = '1' then
	if count < 8 then 
		count <= count + 1; 
	else
		count <= "0000"; 
	end if;
	if count < 5 then
		cont1 <= '0';
	else
		cont1 <= '1';
	end if;
end if;
		
if clk'event and clk = '0' then
	if count1 < 8 then  	
		count1 <= count1 + 1; 
	else
		count1 <= "0000"; 
	end if;
	if count1 < 5 then
		cont <= '0';
	else
		cont <= '1';
	end if;
end if;
	  
pout <= cont or cont1;

end process;
end bhv;