decoder.vhd

一个用VHDL编写的在CPLD上实现模拟交通灯的程序源代码

library  ieee;
use  ieee.std_logic_1164.all;

entity  decoder  is
port(din  : in std_logic_vector(3 downto 0);
     a,b,c,d,e,f,g  :out  std_logic  
     );
end  decoder;

architecture  behave of  decoder is
signal  decod_out  :std_logic_vector(6 downto 0);
begin
    process(din)
     begin
       case  din  is
       when  "0000"    =>  decod_out<="1111110";
       when  "0001"    =>  decod_out<="0110000";
       when  "0010"    =>  decod_out<="1101101";
       when  "0011"    =>  decod_out<="1111001";
       when  "0100"    =>  decod_out<="0110011";
       when  "0101"    =>  decod_out<="1011011";
       when  "0110"    =>  decod_out<="1011111";
       when  "0111"    =>  decod_out<="1110000";
       when  "1000"    =>  decod_out<="1111111";
       when  "1001"    =>  decod_out<="1111011";
       when  "1010"    =>  decod_out<="1110111";
       when  "1011"    =>  decod_out<="0011111";
       when  "1100"    =>  decod_out<="1001110";
       when  "1101"    =>  decod_out<="0111101";
       when  "1110"    =>  decod_out<="1001111";
       when  "1111"    =>  decod_out<="1000111";
       when   others   => null;
      end  case;
    end  process;
             a<=decod_out(6);
             b<=decod_out(5);
             c<=decod_out(4);
             d<=decod_out(3);
             e<=decod_out(2);
             f<=decod_out(1);
             g<=decod_out(0);
      

end  behave;