led.vhd

矩阵键盘的vhdl编程,非常的实用,带有去抖动

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

entity led is 
port(
     key_code: in std_logic_vector(7 downto 0);
     display: out std_logic_vector(7 downto 0);
     seg:     out std_logic_vector(1 downto 0)
    );
end led;
architecture rtl of led is
	signal code:  std_logic_vector(3 downto 0);	
   begin 
	code <= key_code(3) & key_code(2) & key_code(1) & key_code(0);
	process(code)
     begin
	  case (code) is

	  when "0000" =>
	   display <="00000011";
	  when "0001"=>
	   display <="10011111";
      when "0010"=>
      display<="00100101";
      when "0011"=>
      display<="00001101";
      when "0100"=> 
      display<="10011001";
      when "0101"=>
      display<="01001001";
      when "0110"=>
      display<="01000001";
      when "0111"=>
      display<="00011111";
      when "1000"=>
      display<="00000001";
      when "1001"=>
      display<="00001001";

      when "1010"=>
      display<="10011111";
      when "1011"=>
      display<="00100101";
      when "1100"=>
      display<="00001101";
      when "1101"=>
      display<="10011001";
      when "1110"=>
      display<="01001001";
      when "1111"=>
      display<="01001001";
      when others=>display<="11111111";
     end case;
   end process;
   process(code)
   begin
    if(code(3)='1') then
       if((code(2)='1') OR  (code(1)='1')) then
          seg<="10";
       else
          seg<="01";
       end if;
     else
       seg<="01";
    end if;
   end process;
end;