fenpin.vhd

（1）、自动售货机可以出售4种货物

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

entity fenpin is
port ( clk      :in std_logic;                                      
       clk1     :out std_logic;
       clk2,clk3:out std_logic);
end;
architecture a of fenpin is
     signal count:std_logic_vector(12 downto 0);
     signal a,c  :std_logic;
begin
p1:
   process(clk)
   begin
       if(clk'event and clk='1')then 
       if(count="1001110001000")then
           count<="0000000000000"; a<=not a;
       else count<=count+1;
       end if;
      end if;
clk2<=a;
clk3<=a;
end process p1;
p2:
    process(a)
    begin
        if(a'event and a='1')then 
            c<=not c;
        end if;
    clk1<=c;
    end process;
end;