报错信息：Multiple non-tristate drivers for net count_int(7) in aa4

          Multiple non-tristate drivers for net count_int(6) in aa4

          ................

         八个输出端都不对

--8位UP/DOWN计数器
LIBRARY ieee;
USE ieee.Std_logic_1164.ALL;
USE ieee.Std_logic_unsigned.ALL;

ENTITY aa4 IS
        GENERIC(n : Positive := 8);
        PORT(s1,s2,en,reset: IN Std_logic;
             count : OUT Std_logic_vector((n-1) DOWNTO 0));
END aa4;

ARCHITECTURE v1 OF aa4 IS
        SIGNAL count_int : Std_logic_vector((n-1) DOWNTO 0);
       --   count_int <= (OTHERS => '0');
BEGIN
          count_int <= (OTHERS => '0');
        PROCESS
       
        BEGIN
                wait until (en='1');  --使能

                  if (reset='1') then 
                   count_int <= (OTHERS => '0');  --清零

                  elsif(s1'EVENT AND s1 = '1' and s2='1') then 
                   count_int<=count_int+1;  --s1上升沿且s2为高时加记数

                  elsif(s1'EVENT AND s1 = '0' and s2='1') then
                   count_int<=count_int-1;  --s1下降沿且s2为高时减记数

                ELSE
                        NULL;
                END IF;
        END PROCESS;
        count <= count_int;
END v1;

PROCESS后面没有敏感信号表？

另：WAIT在max+plusII中不被支持，无法使用

[此贴子已经被stone133于2006-4-14 13:39:14编辑过]

process的敏感信号表和wait until不能同时使用,建议不要使用wait,因为很多软件不支持它;

处理方法:

1.去掉wait,用if代替这个判断

2.process的敏感信号表加入敏感信号

3.不要用双沿处理,这样直接用会出问题

[此贴子已经被stone133于2006-4-14 15:35:02编辑过]