--我感觉这应该没有问题,但是编译出现一下错误:
The error is:Else Clause fllowing a clock edge must hold the state of
sigal "digital8";后来我设置一个信号量k,先判断key1是上升还是下降,
然后对这个赋值(00000000或11111111),在最后将这个信号量再给digital8,
程序修改如下if(key1'event and key1='0') then
k <="00000000";
else k <="11111111";
end if;
digital8 <=k;
这样出现的错误是:The error is:Else Clause fllowing a clock edge must hold the state of
sigal "k"。不知这是为什么,望高手指点,谢谢!!!!
ENTITY rh1 IS
PORT( key1: IN std_logic;--定义一个输入
digital8: OUT std_logic_vector(7 downto 0)--8个输出
);
END rh1;
ARCHITECTURE xq OF rh1 IS
--signal k :std-logic-vector(7 downto 0);
begin
digital8 <="00000000" when key1='0' else --数码管全亮
"11111111" ; --数码管全灭
end xq;
process(key1)
begin
digital8 <="00000000" when key1='0' else --数码管全亮
"11111111" ; --数码管全灭
end process;
end xq;
则编译就会出现错误:sequential signal assignment cannot contain conditional waveforms 这是为什么呢???小弟刚开始学,各位大虾可能觉得太容易,
也望高手们耐心指点,小弟感谢万分!!!!