vhdl数字频率计程序_DDS

ID:704585 · 发表于 2020-4-7 14:18

数字频率计_DDS

单片机源程序如下:

LIBRARY ieee;
USE ieee.std_logic_1164.all;
USE ieee.std_logic_unsigned.all;
USE ieee.std_logic_arith.all;
ENTITY dds_dds IS
port(ftw: in std_logic_vector(23 downto 0); --频率控制字
clk: in std_logic; --系统时钟
rec: in std_logic; --接收信号使能
out_q: out std_logic_vector(9 downto 0); --幅度值输出
ack: out std_logic); --接收应答信号
END dds_dds;
ARCHITECTURE beh of dds_dds is
signal phase_adder,frq_reg:std_logic_vector(23 downto 0);
signal rom_address,address:std_logic_vector(9 downto 0);
signal rom_out:std_logic_vector(9 downto 0);
signal s_1,s_2,a_1,a_2:std_logic;
signal a:std_logic;
component dds_dds_rom --定义ROM元件
PORT(address : IN STD_LOGIC_VECTOR (9 DOWNTO 0);
q : OUT STD_LOGIC_VECTOR (9 DOWNTO 0));
end component;
begin
data: dds_dds_rom port map(address,rom_out);
datain: process(clk) --数据输入部分
begin
if(clk'event and clk='1') then --clk上升沿触发
if(rec='1') then --rec为1则读取ftw数据并将应答信号ack置1
frq_reg<=ftw;
ack<='1';
a<='1'; --a与ack内容相同在判断时使用
end if;
if(a='1') then --检测到上一个周期ack为1，则将其复位
ack<='0';
a<='0';
end if;
end if;
end process;
phase_add: process(clk) --相位累加部分
begin
if(clk'event and clk='1') then --clk上升沿触发
phase_adder<=phase_adder+frq_reg; --进行相位累加
rom_address(0)<=phase_adder(12);
rom_address(1)<=phase_adder(13);
rom_address(2)<=phase_adder(14);
rom_address(3)<=phase_adder(15);
rom_address(4)<=phase_adder(16);
rom_address(5)<=phase_adder(17);
rom_address(6)<=phase_adder(18);
rom_address(7)<=phase_adder(19);
rom_address(8)<=phase_adder(20);
rom_address(9)<=phase_adder(21);
s_2<=phase_adder(22);
s_1<=phase_adder(23); --将上一个累加值的高12位送出
end if;
end process;
lookfor_rom: process(clk) --ROM查找部分
begin
if(clk'event and clk='1') then --clk上升沿触发
a_1<=s_1; --a_1和a_2比s_1和s_2落后一个周期
a_2<=s_2;
if(s_1='0' and s_2='0') then --将各区间的地址对应到0～π/2的地址
address<=rom_address;
elsif(s_1='0' and s_2='1') then
address<=NOT rom_address;
elsif(s_1='1' and s_2='0') then
address<=rom_address;
elsif(s_1='1' and s_2='1') then
address<=NOT rom_address;
end if; -- NOT rom_address＝3FF－rom_address
if(a_1='0' and a_2='0') then --将各区间的幅度对应到0～π/2的幅度
out_q<=rom_out; --由于幅度比地址输出慢一个周期所以用
-- a_1和a_2进行判断，a_1和a_2比s_1
--和s_2落后一个时钟周期
elsif(a_1='0' and a_2='1') then
out_q<=rom_out;
elsif(a_1='1' and a_2='0') then
out_q<=NOT rom_out+"0000000001";
elsif(a_1='1' and a_2='1') then
out_q<=NOT rom_out+"0000000001";
end if; --负数通过正数取反再加1得到
end if;
end process;
end beh;

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数字频率计_DDS.rar (3.31 KB, 下载次数: 13)

ID:984711 · 发表于 2021-11-29 14:22

频率测量的范围大概在哪一个阶段？

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