bufu1.vhd

出租车的计费系统

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity bufu1 is
  port(clk,reset,stop    :in std_logic;
       co                :out std_logic);
end bufu1;
architecture cnt_100_x of bufu1 is
     signal shi,bai:std_logic_vector(3 downto 0);
begin
    process(reset,clk,stop)
    begin                                                        
        
        if(reset='1' ) then
          shi<="0000";bai<="0000";
        else if(clk'event and clk='1') then
             if(shi=9) then shi<="0000";
                if (bai=9) then bai<="0000";
                   else bai<=bai+1;
                end if;
               else shi<=shi+1;
              end if;
       if(shi=9 and bai=9) then
           co<='1';
         else 
           co<='0';
      end if;
      end if; 
      end if;
       if(stop='1') then
          shi<=shi;
          bai<=bai;
       end if;
    
end process;
end cnt_100_x;