diff --git a/src/main/scala/backBoard/ebus/CDROut.scala b/src/main/scala/backBoard/ebus/CDROut.scala
index 9f0855b..48d8cf9 100644
--- a/src/main/scala/backBoard/ebus/CDROut.scala
+++ b/src/main/scala/backBoard/ebus/CDROut.scala
@@ -20,7 +20,7 @@ class CDROutIO extends Bundle{
 
 class CDROut extends Module{
   val io: CDROutIO = IO(new CDROutIO)
-  def PRE_NUM = 3 //PRE_NUM should >= 2
+  def PRE_NUM = 3 //PRE_NUM should >= 3
 
 
   def STATE_IDLE  = 0.U