frequence.vhd

输入为八位十进制数

library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_unsigned.all;

entity frequence is
  port(
       fin         : in  std_logic;
       clk_1Hz     : in  std_logic;
       douta       : out std_logic_vector(4 downto 0);
       doutb       : out std_logic_vector(4 downto 0);
       doutc       : out std_logic_vector(4 downto 0);
       doutd       : out std_logic_vector(4 downto 0)
      );
end;

architecture behav of frequence is

signal clk_half                          : std_logic;
signal r_1,r_2,r_3,r_4,r_5               : std_logic_vector(4 downto 0);
signal t_1,t_2,t_3,t_4,t_5               : std_logic_vector(4 downto 0);

begin
   process(clk_1Hz)
     begin
       if rising_edge(clk_1Hz) then 
            clk_half<=NOT clk_half;
       end if;
           
   end process;
   
   process(fin,clk_half)
    begin
     if rising_edge(fin) then
         if clk_half='1' then r_1<=r_1+1;
                              if r_1>"01001" then r_1<="00000"; r_2<=r_2+1; end if;
                              if r_2>"01001" then r_2<="00000"; r_3<=r_3+1; end if;
                              if r_3>"01001" then r_3<="00000"; r_4<=r_4+1; end if;
                              if r_4>"01001" then r_4<="00000"; r_5<=r_5+1; end if;
                              if r_5>"01001" then r_1<="01001"; r_2<="01001"; r_3<="01001"; 
                                                  r_4<="01001"; r_5<="01001"; end if;
         elsif clk_half='0'  then 
                  r_1<="00000";r_2<="00000";r_3<="00000";r_4<="00000";r_5<="00000";
         end if;       
     end if;   
    end process;
  
  process(clk_half)
     begin
      if falling_edge(clk_half) then
          t_1<=r_1;   t_3<=r_3;  t_5<=r_5;
          t_2<=r_2;   t_4<=r_4;
      end if;
   end process;
-------------------------------------------------------------------------------------------

process(t_1,t_2,t_3,t_4,t_5)
  begin
    if t_5="00000" then 

		if t_4="00000" then douta<="11111";
        else douta<=t_4; end if;

        if t_3="00000" then doutb<="11111";
        else doutb<=t_3; end if;

        if t_2="00000" then doutc<="11111";
        else doutc<=t_2; end if;
           
        doutd<=t_1;

    else  doutd<=t_2;doutc<=t_3;
          doutb<=t_4+"10000";
          douta<=t_5;
    end if;
end process;
end;