decoder.vhd

VHDL实现的电子钟的基本功能

--文件名：decoder.vhd。
--功能：将4bit二进制数译码，在LED上显示相应数字。
--最后修改日期：2009.4.18
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity decoder is
Port (din:in std_logic_vector(3 downto 0 );   --四位二进制码输入
      dout:out std_logic_vector(7 downto 0) );  --输出LED七段码
end decoder;
architecture bhv of decoder is
  begin
  process(din)
    begin
    case din is
    when "0000" => dout<="10000000";--0
    when "0001" => dout<="10000000";--1
    when "0010" => dout<="11011010";--2
    when "0011" => dout<="11110010";--3
    when "0100" => dout<="01100110";--4
    when "0101" => dout<="10110110";--5
    when "0110" => dout<="10111110";--6
    when "0111" => dout<="11100000";--7
    when "1000" => dout<="11111110";--8
    when "1001" => dout<="11110110";--9
    when others => dout<="00000000";
    end case;
  end process;
end bhv;