DC 同步功能； 基于IO的下级从机热插入

src/main/scala/backBoard/BackBoardSlv.scala

@@ -17,6 +17,11 @@ class BackBoardSlvIO extends Bundle{
   val lvds_down_dout = Output(Bool())
   val lvds_up_din    = Input(Bool())
   val lvds_up_dout   = Output(Bool())
+
+  val isOnline = Output(Bool())
+  val isLast   = Input(Bool())
+
+  val DCIn   = Input(Bool())
 }