1(1).txt

3-8译码器,BCD码转换10进制,计数器

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY DECODER IS
  PORT(
       A :IN STD_LOGIC_VECTOR(2 DOWNTO 0);
       
       Y  :OUT STD_LOGIC_VECTOR(7 DOWNTO 0)
      );
   END DECODER;

ARCHITECTURE  A OF DECODER IS
SIGNAL SEL:STD_LOGIC_VECTOR(2 DOWNTO 0);
BEGIN
   
   SEL(0)<=A(0);
   SEL(1)<=A(1);
   SEL(2)<=A(2);
 PROCESS(SEL)
  BEGIN 
   CASE A IS
    WHEN "000"=> Y<="00000001";
    WHEN "001"=> Y<="00000010";
    WHEN "010"=> Y<="00000100";
    WHEN "011"=> Y<="00001000";
    WHEN "100"=> Y<="00010000";
    WHEN "101"=> Y<="00100000";
    WHEN "110"=> Y<="01000000";
    WHEN "111"=> Y<="10000000";
    WHEN OTHERS=>NULL;
   END CASE;
  END PROCESS;
END A;