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数字频率计原理功能 第2页

更新时间:2008-11-23:  来源:毕业论文

数字频率计原理

         clr<='1' ;

            when 0=>en<='1';

                       load<='0';

                            clr<='0';

  end case;

  end if;

  end process;

 

 

end Behavioral;

十进制计数器:

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.STD_LOGIC_ARITH.ALL;

use IEEE.STD_LOGIC_UNSIGNED.ALL;

 

entity count10 is

   Port ( reset : in std_logic;

          enable : in std_logic;

          clk : in std_logic;

          cout : out std_logic;

          q : out std_logic_vector(3 downto 0));

end count10;

 

architecture Behavioral of count10 is

signal q_tmp: std_logic_vector(3 downto 0);

begin

process(clk)

begin

if (clk 'event and clk='1')then

  if reset='1' then

  q_tmp<="0000";

  elsif enable='1' then

  if q_tmp="1001" then

  q_tmp<="0000";

  else q_tmp<=q_tmp+1;

  end if;

  end if;

  end if;

  q<=q_tmp;

 

  if (q_tmp="1001" and enable='1')   then cout<='1';

 

  else cout<='0';

 

end if;

 end process;

end Behavioral;

 

锁存器

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.STD_LOGIC_ARITH.ALL;

use IEEE.STD_LOGIC_UNSIGNED.ALL;

 

entity latch is

   Port ( data : in std_logic_vector(23 downto 0);

          oe: in std_logic;

          g : in std_logic;

          q : out std_logic_vector(23 downto 0));

end latch;

 

architecture Behavioral of latch is

signal q_tmp: std_logic_vector (23 downto 0);

begin

process (oe,g)

begin

if oe='0' then

if g'event and g='1' then

q_tmp<=data;

end if;

else q<=q_tmp;

end if;

 end process;

end Behavioral;

扫描电路:

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.STD_LOGIC_ARITH.ALL;

use IEEE.STD_LOGIC_UNSIGNED.ALL;

 

entity scan is

   Port ( clk0: in std_logic;

          vin : in std_logic_vector(23 downto 0);

          vout : out std_logic_vector(3 downto 0);

          d : out std_logic_vector(2 downto 0));

end scan;

 

architecture Behavioral of scan is

signal c: integer range 0 to 5;

 

begin

process(clk0)

begin if (clk0 'event and clk0='1') then

if c=5 then c<=0;

else c<=c+1;

end if;

case c is when 0=>vout<=vin(3)&vin(2)&vin(1)&vin(0);

                    d<="101";

         when 1=>vout<=vin(7)&vin(6)&vin(5)&vin(4);

                       d<="100";

             when 2=>vout<=vin(11)&vin(10)&vin(9)&vin(8);

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