VHDL数控分频器编程
的有关信息介绍如下：
本经验向你展示如何使用VHDL编写数控分频器的电路。数控分频器的应用广泛，例如使用数控分频器产生特定频率是蜂鸣器发出声音，等等。
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY speaker IS
PORT(clk:IN STD_LOGIC;
tone:IN STD_LOGIC_VECTOR (11 DOWNTO 0);
spk:OUT STD_LOGIC);
END ENTITY speaker;
ARCHITECTURE one OF speaker IS
SIGNAL preclk:STD_LOGIC;
SIGNAL fullspk:STD_LOGIC;
BEGIN
---------------------
divclk:PROCESS(clk)
VARIABLE Count8:STD_LOGIC_VECTOR (3 DOWNTO 0);
BEGIN
IF (clk'EVENT AND clk='1') THEN
IF Count8>7 THEN preclk<=NOT preclk;Count8:="0000";
ELSE Count8:=Count8+1;
END IF;
END IF;
END PROCESS divclk;
----------------------
genspk:PROCESS(preclk,tone)
VARIABLE Count12:STD_LOGIC_VECTOR(11 DOWNTO 0);
BEGIN
IF (preclk'EVENT AND preclk='1') THEN
IF Count12=16#FFF# THEN Count12:=tone;fullspk<='1';
ELSE Count12:=Count12+1;fullspk<='0';
END IF;
END IF;
END PROCESS genspk;
----------------------
delayspk:PROCESS (fullspk)
VARIABLE Count2:STD_LOGIC;
BEGIN
IF (fullspk'EVENT AND fullspk='1') THEN Count2:=NOT Count2;
IF Count2='1' THEN spk <='1';
ELSE spk<='0';
END IF;
END IF;
END PROCESS delayspk;
END ARCHITECTURE one;
进行波形仿真
说明：
tone即是分频系数
spk既是产生的信号
