key_fun.txt

VHDL 软件防按键抖动程序

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
ENTITY KEY_FUN IS
GENERIC(MAX_VALUE_MS :INTEGER :=10000);
 PORT
 (
  CLK       : IN  STD_LOGIC;
  KEY_IN    : IN  STD_LOGIC;
  KEY_OUT   : BUFFER STD_LOGIC
  );
END ENTITY;
ARCHITECTURE a OF KEY_FUN IS
 BEGIN
------------按键操作进程----------
PROCESS
 VARIABLE COUNT :INTEGER RANGE 0 TO MAX_VALUE_MS;
 VARIABLE FLAG_KEY_OUT,FLAG_HIT: STD_LOGIC;
BEGIN
 WAIT UNTIL RISING_EDGE(CLK);
 IF COUNT=MAX_VALUE_MS THEN                    --分频产生10毫秒信号
   COUNT:=0;
  IF KEY_IN = '1' AND FLAG_HIT = '0' THEN      --A按键去抖动操作
    FLAG_HIT:='1';
    FLAG_KEY_OUT:='0';
  ELSIF KEY_IN = '0' AND FLAG_HIT='1' THEN
    FLAG_HIT:='0';
    FLAG_KEY_OUT:='1'; 
  END IF;
 ELSE
  COUNT:=COUNT+1;
  IF FLAG_KEY_OUT='1'AND KEY_OUT='0'THEN      --输出基准脉冲
   FLAG_KEY_OUT:='0';
   KEY_OUT<='1';
  ELSE
   KEY_OUT<='0';
  END IF;
 END IF;
END PROCESS;
END a;