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下面是程序,但仿真波形怎么都不对,以前在工程中我用过这模块,没问题。
问题出在哪?
LIBRARY ieee;
USE ieee.std_logic_1164.ALL;
ENTITY bidir IS
PORT(
bidir : INOUT STD_LOGIC_VECTOR (7 DOWNTO 0);
oe, clk : IN STD_LOGIC;
inp : IN STD_LOGIC_VECTOR (7 DOWNTO 0);
outp : OUT STD_LOGIC_VECTOR (7 DOWNTO 0));
END bidir;
ARCHITECTURE cpld OF bidir IS
SIGNAL a : STD_LOGIC_VECTOR (7 DOWNTO 0); -- DFF that stores
SIGNAL b : STD_LOGIC_VECTOR (7 DOWNTO 0); -- DFF that stores
BEGIN -- feedback value.
PROCESS(clk)
BEGIN
IF clk = '1' AND clk'EVENT THEN -- Creates the flipflops
a <= inp;
outp <= b;
END IF;
END PROCESS;
PROCESS (oe, bidir) -- Behavioral representation
BEGIN -- of tri-states.
IF( oe = '0') THEN
bidir <= "ZZZZZZZZ";
b <= bidir;
ELSE
bidir <= a;
b <= bidir;
END IF;
END PROCESS;
END cpld; |
阿莫论坛20周年了!感谢大家的支持与爱护!!
知道什么是神吗?其实神本来也是人,只不过神做了人做不到的事情 所以才成了神。 (头文字D, 杜汶泽)
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