lcnt8.vhd

来自「EDA技术应用.用QUARTUES II 实现EDA技术实验操作,类似于精典的M」· VHDL 代码 · 共 27 行

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY  LCNT8  IS
   PORT(CLK, LD: IN STD_LOGIC;
                   D: IN INTEGER RANGE 0 TO 255;
                   CAO: OUT STD_LOGIC);
END ENTITY LCNT8;
ARCHITECTURE ART OF LCNT8 IS
SIGNAL COUNT: INTEGER RANGE 0 TO 255;
BEGIN
PROCESS(CLK)IS
BEGIN
        IF CLK'EVENT AND CLK='1' THEN
                 IF LD='1' THEN COUNT<=D;
                        ELSE COUNT<=COUNT+1;
                   END IF;
           END IF;
END PROCESS;
       PROCESS(CLK,COUNT) IS
       BEGIN
              IF CLK'EVENT AND CLK='1' THEN
                 IF COUNT=255 THEN CAO<='1';
                       ELSE CAO<='0';
                  END IF;
             END IF;
END PROCESS;
END ARCHITECTURE ART;