数字频率计vhdl程序.txt

数字频率计VHDL程序 --文件名：plj.vhd。 --功能：频率计。具有4位显示

      数字频率计VHDL程序

      --文件名：plj.vhd。
      --功能：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;