dcnt6.vhd

微波炉控制器的设计

--DCNT6.VHD
  LIBRARY IEEE;
  USE IEEE.STD_LOGIC_1164.ALL;
  USE IEEE.STD_LOGIC_UNSIGNED.ALL;
  ENTITY DCNT6 IS
    PORT(CLK:IN STD_LOGIC;
         LOAD:IN STD_LOGIC;
         ENA:IN STD_LOGIC;
         DATAIN:IN STD_LOGIC_VECTOR(3 DOWNTO 0);
         CQ:OUT STD_LOGIC_VECTOR(3 DOWNTO 0);
         CARRY_OUT:OUT STD_LOGIC);
   END ENTITY DCNT6;
  ARCHITECTURE ART OF DCNT6 IS
    SIGNAL CQI:STD_LOGIC_VECTOR(3 DOWNTO 0);
    BEGIN
    PROCESS(CLK,LOAD,ENA)IS
      BEGIN
      IF LOAD='1' THEN
         CQI<=DATAIN;
      ELSIF CLK'EVENT AND CLK='1' THEN
         IF ENA='1' THEN
            IF CQI="0000"THEN CQI<="0101";
            ELSE CQI<=CQI-'1';END IF;
            END IF;
          END IF;
      END PROCESS;
      PROCESS(CLK,CQI)IS
        BEGIN
        IF CLK'EVENT AND CLK='1' THEN
           IF CQI="0000"THEN CARRY_OUT<='1';
           ELSE CARRY_OUT<='0';END IF;
        END IF;
       END PROCESS;
       CQ<=CQI;
      END ARCHITECTURE ART;