select_word.vhd

米字型数码管的编码方法。自动循环显示至少四个以上单词。

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

entity select_word is
port( clk : in std_logic;
      X1,X2,X3,X4 : out std_logic_vector(15 downto 0));
end entity select_word;

architecture art of select_word is
  signal data : std_logic_vector(2 downto 0);
  signal cont : std_logic_vector(3 downto 0);
   begin
  process (clk) is
    begin
    if clk'event and clk='1' then
       if cont = "0000" then
          cont <= "1111";
          if data = "100" then
          data <= "000";
       else
          data <= data + 1;
       end if;
       case data is
	 when "000" => x1<=X"0000"; x2<=X"4a00"; x3<=X"0acc"; x4<=X"0000";  --" MY "
	 when "001" => x1<=X"11f3"; x2<=X"0acc"; x3<=X"11cf"; x4<=X"22cc";  --"NAME"
	 when "010" => x1<=X"0000"; x2<=X"11bb"; x3<=X"4433"; x4<=X"0000";  --" IS "
	 when "011" => x1<=X"22cc"; x2<=X"11cf"; x3<=X"31c7"; x4<=X"0000"; --" RAN"
     when "100" => x1<=X"22cc"; x2<=X"11f3"; x3<=X"11cc"; x4<=X"8833"; --"ZHEN"
     when others => null;
    end case;    
    else
           cont <= cont - 1;
    end if;

    end if;
  end process;
end architecture art;