dec3_8.tdf

有VHDL写的一个38译码器,并付仿真波形.

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY Dec3_8 IS
PORT (A : IN STD_LOGIC_VECTOR( 2 DOWNTO 0) ;
            EN       : IN STD_LOGIC ;
            Y  : OUT STD_LOGIC_VECTOR( 7 DOWNTO 0)) ;
END Dec3_8 ;
ARCHITECTURE  BEHAVE OF Dec3_8 IS
SIGNAL  SEL : STD_LOGIC_VECTOR( 3 DOWNTO 0) ;
BEGIN
   SEL(0) <= EN ;   SEL(1) <= A(0) ;
   SEL(2) <= A(1) ; SEL(3) <= A(2) ;
   WITH SEL SELECT 
       Y<= "00000001" WHEN "0001",
               "00000010" WHEN "0011",
               "00000100" WHEN "0101",
               "00001000" WHEN "0111",
               "00010000" WHEN "1001",
               "00100000" WHEN "1011",
               "01000000" WHEN "1101",
               "10000000" WHEN "1111",
               "11111111" WHEN OTHERS ;
END BEHAVE ;