数字频率计VHDL程序与仿真

频率计。具有4位显示，能自动根据7位十进制计数的结果，自动选择有效数据的 --高4位进行动态显示。小数点表示是千位，即KHz。

library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; entity plj is port ( start:in std_logic; --复位信号 clk :in std_logic; --系统时钟 clk1:in std_logic; --被测信号 yy1:out std_logic_vector(7 downto 0); --八段码 w1 :out std_logic_vector(3 downto 0)); --数码管位选信号 end plj; architecture behav of PLj is signal b1,b2,b3,b4,b5,b6,b7:std_logic_vector(3 downto 0); --十进制计数器 signal bcd:std_logic_vector(3 downto 0); --BCD码寄存器 signal q :integer range 0 to 49999999; --秒分频系数 signal qq : integer range 0 to 499999; --动态扫描分频系数 signal en,bclk:std_logic; --使能信号，有效被测信号 signal sss : std_logic_vector(3 downto 0); --小数点 signal bcd0,bcd1,bcd2,bcd3 : std_logic_vector(3 downto 0); --寄存7位十位计数器中有效的高4位数据 begin

second:process(clk) --此进程产生一个持续时间为一秒的的闸门信号 begin if start='1' then q<=0; elsif clk'event and clk='1' then if q<49999999 then q<=q+1; else q<=49999999; end if; end if; if q<49999999 and start='0' then en<='1'; else en<='0'; end if; end process;

and2:process(en,clk1) --此进程得到7位十进制计数器的计数脉冲 begin bclk<=clk1 and en; end process;

com:process(start,bclk) --此进程完成对被测信号计脉冲数 begin if start='1' then --复位 b1<="0000";b2<="0000";b3<="0000";b4<="0000";b5<="0000";b6<="0000";b7<="0000"; elsif bclk'event and bclk='1' then
if b1="1001" then b1<="0000"; --此IF语句完成个位十进制计数 if b2="1001" then b2<="0000"; --此IF语句完成百位十进制计数 if b3="1001" then b3<="0000"; --此IF语句完成千位十进制计数 if b4="1001" then b4<="0000"; --此IF语句完成万位十进制计数 if b5="1001" THEN b5<="0000"; --此IF语句完成十万位十进制计数 if b6="1001" then b6<="0000"; --此IF语句完成百万位十进制计数 if b7="1001" then b7<="0000"; --此IF语句完成千万位十进制计数 else b7<=b7+1; end if; else b6<=b6+1; end if; else b5<=b5+1; end if; else b4<=b4+1; end if; else b3<=b3+1; end if; else b2<=b2+1; end if; else b1<=b1+1; end if; end if; end process;

process(clk) --此进程把7位十进制计数器有效的高4位数据送如bcd0~3；并得到小数点信息 begin if rising_edge(clk) then if en='0' then if b7>"0000" then bcd3<=b7; bcd2<=b6; bcd1<=b5; bcd0<=b4; sss<="1110"; elsif b6>"0000" then bcd3<=b6; bcd2<=b5; bcd1<=b4; bcd0<=b3; sss<="1101"; elsif b5>"0000" then bcd3<=b5; bcd2<=b4; bcd1<=b3; bcd0<=b2; sss<="1011"; else bcd3<=b4; bcd2<=b3; bcd1<=b2; bcd0<=b1; sss<="1111"; end if; end if; end if; end process;

weixuan:process(clk) --此进程完成数据的动态显示 begin if clk'event and clk='1' then if qq< 99999 then qq<=qq+1;bcd<=bcd3; w1<="0111"; if sss="0111" then yy1(0)<='0'; else yy1(0)<='1'; end if; elsif qq<199999 then qq<=qq+1;bcd<=bcd2; w1<="1011"; if sss="1011" then yy1(0)<='0'; else yy1(0)<='1'; end if; elsif qq<299999 then qq<=qq+1;bcd<=bcd1; w1<="1101"; if sss="1101" then yy1(0)<='0'; else yy1(0)<='1'; end if; elsif qq<399999 then qq<=qq+1;bcd<=bcd0; w1<="1110"; if sss="1110" then yy1(0)<='0'; else yy1(0)<='1'; end if; else qq<=0; end if; end if; end process;

m0: process (bcd) --译码 begin case bcd is when "0000"=>yy1(7 downto 1)<="0000001"; when "0001"=>yy1(7 downto 1)<="1001111"; when "0010"=>yy1(7 downto 1)<="0010010"; when "0011"=>yy1(7 downto 1)<="0000110"; when "0100"=>yy1(7 downto 1)<="1001100"; when "0101"=>yy1(7 downto 1)<="0100100"; when "0110"=>yy1(7 downto 1)<="1100000"; when "0111"=>yy1(7 downto 1)<="0001111"; when "1000"=>yy1(7 downto 1)<="0000000"; when "1001"=>yy1(7 downto 1)<="0001100"; when others=>yy1(7 downto 1)<="1111111"; end case; end process; end behav;