jfq3.vhd

出租车计费系统的 实现

Library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
USE IEEE.STD_LOGIC_ARITH.ALL;
entity JFQ3 is
port (
         CLK3,RESET,CON:in std_logic;
         COF :OUT  STD_LOGIC;
                MONEY4:OUT  INTEGER RANGE 9 DOWNTO	0   );
end;
architecture behv of JFQ3 is
 SIGNAL CO: STD_LOGIC;

   BEGIN
     PROCESS(CLK3,CON)
      VARIABLE CNT:INTEGER RANGE 9 DOWNTO 0;
          BEGIN
     IF RESET ='1' THEN CNT:=0;
       ELSIF CLK3'EVENT AND CLK3='1' THEN
          IF CON='1' 
         THEN 
           CNT:=CNT+1;
         IF CNT>1
           THEN CO<='1';
           ELSE CO<='0';
         END IF;
      END IF;
   END IF;
MONEY4<=CNT;
COF<=CO;

END PROCESS;
END ;