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| 我想实现的功能是:上电后,led灭,当按键按下一后,对应的led点亮,即使按键松开,led依然亮,我的程序如下: LIBRARY IEEE;
 USE IEEE.STD_LOGIC_1164.ALL;
 ENTITY TEST_1 IS
 PORT(S:IN STD_LOGIC;
 L:OUT STD_LOGIC;
 NUM:BUFFER INTEGER RANGE 0 TO 1:=0);
 END TEST_1;
 ARCHITECTURE ONE OF TEST_1 IS
 BEGIN
 PROCESS(S)
 BEGIN
 IF(S='0') THEN
 NUM<=1;
 END IF;
 END PROCESS;
 PROCESS(NUM)
 BEGIN
 CASE NUM IS
 WHEN 0=>L<='0';
 WHEN 1=>L<='1';
 END CASE;
 END PROCESS;
 END ONE;
 但是上电后对应的灯就亮了.....郁闷,请大家帮助一下,谢谢!
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