Error (10028): Can't resolve multiple constant drivers for net "out2" at shiyan.v(14)解决办法

//Error（10028）：Can't resolve multiple constant drivers for net “ ” at **.v

//两个进程里都有同一个条件判断的话，会产生并行信号冲突的问题。

//同一个信号不允许在多个进程中赋值，否则则为多驱动。

//进程的并行性决定了多进程不同能对同一个对象进行赋值。

 1 module test(c1,c2,out1,out2);

 input c1,c2;
 output out1,out2;

 reg out1,out2;

 always @(posedge c1)
     begin
         out1<=;
         out2<=;
     end

 always@(posedge c2)
     begin
         out1<=;
         out2<=;
     end

 endmodule                    

上面的代码在quartusII里面就会出现题目的错误提示，器原因就是在两个always语句里面都对out1,out2信号赋值了，而两个always是并行快，所以提示出现多重驱动的情况。。。

解决办法：

将两个always合并为一个

 module shiyan(c1,c2,out1,out2);
 input c1,c2;
 output out1,out2;

 reg out1,out2;

 always @(posedge c1 or posedge c2)
     if(c1==)
         begin
             out1<=;
             out2<=;
         end

    else
         begin
             out1<=;
             out2<=;
         end
 endmodule

摘自网络：

http://blog.sina.com.cn/s/blog_5c5263cf0100qd2q.html

http://www.cnblogs.com/woshitianma/archive/2013/01/12/2858051.html