diff --git a/src/main/scala/mac/AsyncFifo.scala b/src/main/scala/mac/AsyncFifo.scala
new file mode 100644
index 0000000..2a5d5c3
--- /dev/null
+++ b/src/main/scala/mac/AsyncFifo.scala
@@ -0,0 +1,74 @@
+
+
+package MAC
+
+import chisel3._
+import chisel3.util._
+
+
+    val write   = Input(Bool())
+    val read    = Input(Bool())
+    val clear   = Input(Bool())
+    val data_in = Input(UInt(dw.W))
+
+    val data_out = Output(UInt(dw.W))
+    val almost_full = Output(Bool())
+    val full = Output(Bool())
+    val almost_empty = Output(Bool())
+    val empty = Output(Bool())
+
+
+    val cnt = Output(UInt(cntw.W))
+
+
+class AsyncFifo(dw: Int, aw: Int) extends RawModule{
+
+  def dp: Int = { var res = 1; for ( i <- 0 until aw ) { res = res * 2 }; return res }
+
+  class AsyncFifoIO extends Bundle{
+    val clockEnq = Input(Bool())
+    val clockDeq = Input(Bool())
+    val resetEnq = Input(Bool())
+    val resetDeq = Input(Bool())
+
+    val enq = Flipped(Decoupled(UInt(dw.W)))
+    val deq = Decoupled( UInt(dw.W) )
+
+    val almost_full = Output(Bool())
+    val almost_empty = Output(Bool())
+
+    def full  = ~enq.ready
+    def empty = ~deq.valid
+
+  }
+
+  val io: AsyncFifoIO = IO(new AsyncFifoIO)
+
+  val fifo = withClockAndReset( io.clockEnq.asClock, io.reset ) (Mem( dp, UInt(dw.W) ))
+
+
+  val wrPtr = withClockAndReset( io.clockEnq.asClock, io.resetEnq ) (RegInit(0.U((aw+1).W)))
+  val wrPrtGray = BinaryToGray(wrPtr)
+
+  val rdPtr = withClockAndReset( io.clockDeq.asClock, io.resetDeq ) (RegInit(0.U((aw+1).W)))
+  val rdPrtGray = BinaryToGray(rdPtr)
+
+  val wrPrtGraySync = withClockAndReset( io.clockDeq.asClock, io.resetDeq ) ( ShiftRegister( wrPrtGray, 2, 0.U, true.B ) )
+  val rdPrtGraySync = withClockAndReset( io.clockEnq.asClock, io.resetEnq ) ( ShiftRegister( rdPrtGray, 2, 0.U, true.B ) )
+
+  val isEmpty = wrPrtGraySync === rdPrtGray
+  val isFull  = (wrPrtGray(aw-2, 0) === rdPrtGraySync(aw-2, 0)) & (wrPrtGray.extract(aw-1) =/= rdPrtGraySync.extract(aw-1))
+
+  io.enq.ready := ~isFull
+  io.deq.valid := ~isEmpty
+
+  withClockAndReset( io.clockEnq.asClock, io.resetEnq ){
+    when( io.enq.fire ){
+      fifo(wrPtr) := io.enq.bits
+    }
+  }
+
+  io.deq.bits := fifo(rdPtr)
+
+
+}
diff --git a/src/main/scala/mac/MacTilelink.scala b/src/main/scala/mac/MacTilelink.scala
index b4146ab..aa517af 100644
--- a/src/main/scala/mac/MacTilelink.scala
+++ b/src/main/scala/mac/MacTilelink.scala
@@ -72,13 +72,17 @@ abstract class MacTileLinkBase(edgeIn: TLEdgeIn, edgeOut: TLEdgeOut) extends Mod
 
 
     val BlockingTxStatusWrite = Output(Bool())
-    val TxStartFrm_wb = Output(Bool())
-    val ReadTxDataFromFifo_sync = Input(Bool())
 
-    val TxStartFrm_syncb = Input(Bool())
-    val TxUnderRun_wb = Output(Bool())
+    val ReadTxDataFromFifo_sync = Input(Bool())
     val TxData_wb = Output(UInt(32.W))
     val TxValidBytesLatched = Output(UInt(2.W))
+    
+    val TxStartFrm_wb = Output(Bool())
+    val TxStartFrm_syncb = Input(Bool())
+
+    val TxUnderRun_wb = Output(Bool())
+
+
     val TxEndFrm_wb = Output(Bool())
 
     val TxRetrySync  = Input(Bool())