diff --git a/.devcontainer.json b/.devcontainer.json
index 4d3b00d..377fa15 100644
--- a/.devcontainer.json
+++ b/.devcontainer.json
@@ -1,3 +1,4 @@
 {
-  "image": "datenlord/spinal-cocotb:1.5.0"
+  "image": "datenlord/spinal-cocotb:1.6.0",
+  "extensions": ["scalameta.metals"]
 }
diff --git a/exercises/Dockerfile b/exercises/Dockerfile
index a05a8db..40c6744 100644
--- a/exercises/Dockerfile
+++ b/exercises/Dockerfile
@@ -2,7 +2,7 @@ FROM ubuntu
 
 ARG JDK_VERSION=11
 ARG MILL_VERSION=0.9.7
-ARG SCALA_VERSION=2.12.13
+ARG SCALA_VERSION=2.13.6
 ENV DEBIAN_FRONTEND=noninteractive
 
 # Install dependencies
diff --git a/exercises/Examples/src/main/scala/exercises/ApbArbiter.scala b/exercises/Examples/src/main/scala/exercises/ApbArbiter.scala
index 4dbc195..99d4dbc 100644
--- a/exercises/Examples/src/main/scala/exercises/ApbArbiter.scala
+++ b/exercises/Examples/src/main/scala/exercises/ApbArbiter.scala
@@ -11,7 +11,7 @@ class ApbArbiter(
   require(numInputSlaves > 0)
 
   val io = new Bundle {
-    val en = in Bool
+    val en = in Bool ()
     val masterOut = master(Apb3(apbConfig))
     val slavesIn = Vec(slave(Apb3(apbConfig)), numInputSlaves)
   }
diff --git a/exercises/Examples/src/main/scala/exercises/Booth.scala b/exercises/Examples/src/main/scala/exercises/Booth.scala
index db619f4..07772e6 100644
--- a/exercises/Examples/src/main/scala/exercises/Booth.scala
+++ b/exercises/Examples/src/main/scala/exercises/Booth.scala
@@ -11,19 +11,22 @@ class Booth(width: Int) extends Component {
   require(width > 1)
 
   val io = new Bundle {
-    val load = in Bool
+    val load = in Bool ()
     val multiplicand = in SInt (width bits)
     val multipler = in SInt (width bits)
-    val ready = out Bool
+    val ready = out Bool ()
     val product = out SInt (2 * width bits)
   }
 
-  val buf = Reg(SInt(2 * width + 1 bits)) init (0) simPublic ()
-  val upperPart = buf(2 * width downto width + 1) simPublic ()
-  val lowerPart = buf(width downto 0) simPublic ()
-
+  val buf = Reg(SInt(2 * width + 1 bits)) init (0)
+  val upperPart = buf(2 * width downto width + 1)
+  val lowerPart = buf(width downto 0)
   val cnt = CounterFreeRun(stateCount = width + 2)
-  cnt.value simPublic ()
+
+  buf.simPublic()
+  upperPart.simPublic()
+  lowerPart.simPublic()
+  cnt.value.simPublic()
 
   when(io.load) {
     buf := S(0, width bits) @@ io.multipler @@ S(0, 1 bit)
diff --git a/exercises/Examples/src/main/scala/exercises/FifoCC.scala b/exercises/Examples/src/main/scala/exercises/FifoCC.scala
index 1e7eded..fd547ea 100644
--- a/exercises/Examples/src/main/scala/exercises/FifoCC.scala
+++ b/exercises/Examples/src/main/scala/exercises/FifoCC.scala
@@ -16,11 +16,11 @@ class FifoCC[T <: Data](
 
   val io = new Bundle {
     val wData = in(dataType())
-    val wEn = in Bool
-    val wFull = out Bool
+    val wEn = in Bool ()
+    val wFull = out Bool ()
     val rData = out(dataType())
-    val rEn = in Bool
-    val rEmpty = out Bool
+    val rEn = in Bool ()
+    val rEmpty = out Bool ()
   }
 
   val ADDR_WIDTH = log2Up(depth + 1)
diff --git a/exercises/Examples/src/main/scala/exercises/HandShakePipe.scala b/exercises/Examples/src/main/scala/exercises/HandShakePipe.scala
index 3335d0e..30b60c0 100644
--- a/exercises/Examples/src/main/scala/exercises/HandShakePipe.scala
+++ b/exercises/Examples/src/main/scala/exercises/HandShakePipe.scala
@@ -1,24 +1,24 @@
 // https://www.itdev.co.uk/blog/pipelining-axi-buses-registered-ready-signals
+// http://fpgacpu.ca/fpga/Pipeline_Skid_Buffer.html
 
 package exercises
 
 import spinal.core._
-import spinal.core.sim._
 import spinal.lib._
-import spinal.sim._
+import spinal.lib.fsm._
 
 class HandShakePipe(width: Int) extends Component {
   val io = new Bundle {
     val input = new Bundle {
-      val valid = in Bool
+      val valid = in Bool ()
       val payload = in UInt (width bits)
-      val ready = out Bool
+      val ready = out Bool ()
     }
 
     val output = new Bundle {
-      val valid = out Bool
+      val valid = out Bool ()
       val payload = out UInt (width bits)
-      val ready = in Bool
+      val ready = in Bool ()
     }
   }
 }
@@ -154,3 +154,68 @@ class BothHandShakePipe2(
     }
   }
 }
+
+class BothHandShakePipe3(
+    width: Int
+) extends HandShakePipe(width) {
+
+  object SkidBufState extends SpinalEnum {
+    val EMPTY, BUSY, FULL = newElement()
+  }
+
+  val load = Bool()
+  val unload = Bool()
+  val flow = Bool()
+  val fill = Bool()
+  val flush = Bool()
+
+  val insert = io.input.valid && io.input.ready
+  val remove = io.output.valid && io.output.ready
+
+  val skidBufferReg = Reg(UInt(width bits)) init (0)
+  val outBufferReg = Reg(UInt(width bits)) init (0)
+
+  val state = Reg(SkidBufState) init (SkidBufState.EMPTY)
+
+  load := state === SkidBufState.EMPTY && insert && !remove
+  unload := state === SkidBufState.BUSY && !insert && remove
+  flow := state === SkidBufState.BUSY && insert && remove
+  fill := state === SkidBufState.BUSY && insert && !remove
+  flush := state === SkidBufState.FULL && !insert && remove
+
+  when(flush) {
+    outBufferReg := skidBufferReg
+  } elsewhen (load || flow) {
+    outBufferReg := io.input.payload
+  }
+  when(fill) {
+    skidBufferReg := io.input.payload
+  }
+
+  val nextState = SkidBufState()
+  nextState := state
+  switch(state) {
+    is(SkidBufState.EMPTY) {
+      when(load) {
+        nextState := SkidBufState.BUSY
+      }
+    }
+    is(SkidBufState.BUSY) {
+      when(fill) {
+        nextState := SkidBufState.FULL
+      } elsewhen (unload) {
+        nextState := SkidBufState.EMPTY
+      }
+    }
+    is(SkidBufState.FULL) {
+      when(flush) {
+        nextState := SkidBufState.BUSY
+      }
+    }
+  }
+  state := nextState
+
+  io.input.ready := state =/= SkidBufState.FULL
+  io.output.valid := state =/= SkidBufState.EMPTY
+  io.output.payload := outBufferReg
+}
diff --git a/exercises/Examples/test/src/scala/exercises/HandShakePipeTest.scala b/exercises/Examples/test/src/scala/exercises/HandShakePipeTest.scala
index 0c3c219..8f7d825 100644
--- a/exercises/Examples/test/src/scala/exercises/HandShakePipeTest.scala
+++ b/exercises/Examples/test/src/scala/exercises/HandShakePipeTest.scala
@@ -117,7 +117,15 @@ class HandShakePipeTest extends AnyFunSuite {
     stream.io.simPublic()
   }
 
-  def simTest(dut: PipeTB) {
+  class BothPipe3TB(width: Int) extends PipeTB(width) {
+    override val pipe = new BothHandShakePipe3(width)
+    override val stream = new BothPipeStream2(width)
+
+    pipe.io.simPublic()
+    stream.io.simPublic()
+  }
+
+  def simTest(dut: PipeTB): Unit = {
     SimTimeout(1000)
     dut.clockDomain.forkStimulus(2)
 
@@ -145,7 +153,10 @@ class HandShakePipeTest extends AnyFunSuite {
         dut.stream.io.sin.valid #= true
         dut.stream.io.sin.payload #= din
         dut.clockDomain.waitSampling()
-        assert(dut.pipe.io.input.ready.toBoolean == dut.stream.io.sin.ready.toBoolean)
+        assert(
+          dut.pipe.io.input.ready.toBoolean == dut.stream.io.sin.ready.toBoolean,
+          s"pipe ri=${dut.pipe.io.input.ready.toBoolean} not match stream ri=${dut.stream.io.sin.ready.toBoolean}"
+        )
         if (dut.pipe.io.input.valid.toBoolean && dut.pipe.io.input.ready.toBoolean) {
           din += 1
         }
@@ -159,11 +170,14 @@ class HandShakePipeTest extends AnyFunSuite {
         dut.pipe.io.output.ready #= randBool
         dut.stream.io.sout.ready #= randBool
         dut.clockDomain.waitSampling()
-        assert(dut.pipe.io.output.valid.toBoolean == dut.stream.io.sout.valid.toBoolean)
+        assert(
+          dut.pipe.io.output.valid.toBoolean == dut.stream.io.sout.valid.toBoolean,
+          s"pipe vo=${dut.pipe.io.output.valid.toBoolean} not match stream vo=${dut.stream.io.sout.valid.toBoolean}"
+        )
         if (dut.pipe.io.output.valid.toBoolean && dut.pipe.io.output.ready.toBoolean) {
           assert(
             dut.pipe.io.output.payload.toInt == dut.stream.io.sout.payload.toInt,
-            s"dout=${dut.pipe.io.output.payload.toInt} != ${dut.stream.io.sout.payload.toInt}"
+            s"pipe dout=${dut.pipe.io.output.payload.toInt} not match stream dout=${dut.stream.io.sout.payload.toInt}"
           )
           matchCnt += 1
           if (matchCnt > 100) {
@@ -224,5 +238,12 @@ class HandShakePipeTest extends AnyFunSuite {
     .compile(new BothPipe2TB(width))
     .doSim(simTest(_))
   }
+
+  test("pipeline fsm") {
+    SimConfig
+    .withWave
+    .compile(new BothPipe3TB(width))
+    .doSim(simTest(_))
+  }
 }
 
diff --git a/exercises/build.sc b/exercises/build.sc
index 104144d..8259440 100644
--- a/exercises/build.sc
+++ b/exercises/build.sc
@@ -2,10 +2,10 @@ import $ivy.`com.goyeau::mill-scalafix:0.2.2`
 import com.goyeau.mill.scalafix.ScalafixModule
 import mill._, scalalib._, scalafmt._
 
-val SpinalVersion = "1.5.0"
+val SpinalVersion = "1.6.0"
 
 trait CommonSpinalModule extends ScalaModule with ScalafmtModule with ScalafixModule {
-  def scalaVersion = "2.12.13"
+  def scalaVersion = "2.13.6"
   def scalacOptions = Seq("-unchecked", "-deprecation", "-feature")
 
   def ivyDeps = Agg(
@@ -19,14 +19,9 @@ trait CommonSpinalModule extends ScalaModule with ScalafmtModule with ScalafixMo
   def scalafixIvyDeps = Agg(ivy"com.github.liancheng::organize-imports:0.5.0")
 }
 
-
 object Examples extends CommonSpinalModule {
-  object test extends Tests {
-    def ivyDeps = Agg(
-      ivy"org.scalatest::scalatest:3.2.2",
-    )
-    def testFrameworks = Seq("org.scalatest.tools.Framework")
-
+  object test extends Tests with TestModule.ScalaTest {
+    def ivyDeps = Agg(ivy"org.scalatest::scalatest:3.2.2")
     def testOnly(args: String*) = T.command {
       super.runMain("org.scalatest.run", args: _*)
     }