jfq2.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 JFQ2 is
port (
         CLK2,RESET,CON:in std_logic;
         COUT2 :OUT STD_LOGIC;
         MONEY3:OUT  INTEGER RANGE 9 DOWNTO	0   );
end;
architecture behv of JFQ2 is
          
     SIGNAL CO2 : STD_LOGIC;    
BEGIN
  PROCESS(CLK2,CON)
      VARIABLE CNT:INTEGER RANGE 9 DOWNTO 0;
          BEGIN
     IF RESET ='1' THEN CNT:=5;
       ELSIF CLK2'EVENT AND CLK2='1' THEN
          IF CON='1' 
         THEN 
           CNT:=CNT+1;
           IF CNT>9
           THEN CO2<='1';
           CNT:=CNT-10;
           ELSE CO2<='0';
         END IF;
     END IF;
   END IF;
MONEY3<=CNT;
COUT2<=CO2;
END PROCESS;
     

END ;