1 files changed, 61 insertions, 0 deletions
diff --git a/src/test/scala/cookbook/FSM.scala b/src/test/scala/cookbook/FSM.scala
new file mode 100644
index 00000000..58f6a9a2
--- /dev/null
+++ b/src/test/scala/cookbook/FSM.scala
@@ -0,0 +1,61 @@
+// See LICENSE for license details.
+
+package cookbook
+
+import chisel3._
+import chisel3.util._
+
+/* ### How do I create a finite state machine?
+
+ * Use Chisel Enum to construct the states and switch & is to construct the FSM
+ * control logic
+ */
+class DetectTwoOnes extends Module {
+  val io = IO(new Bundle {
+    val in = Input(Bool())
+    val out = Output(Bool())
+  })
+
+  val sNone :: sOne1 :: sTwo1s :: Nil = Enum(3)
+  val state = Reg(init = sNone)
+
+  io.out := (state === sTwo1s)
+
+  switch (state) {
+    is (sNone) {
+      when (io.in) {
+        state := sOne1
+      }
+    }
+    is (sOne1) {
+      when (io.in) {
+        state := sTwo1s
+      } .otherwise {
+        state := sNone
+      }
+    }
+    is (sTwo1s) {
+      when (!io.in) {
+        state := sNone
+      }
+    }
+  }
+}
+
+class DetectTwoOnesTester extends CookbookTester(10) {
+
+  val dut = Module(new DetectTwoOnes)
+
+  // Inputs and expected results
+  val inputs: Vec[Bool] = Vec(false.B, true.B, false.B, true.B, true.B, true.B, false.B, true.B, true.B, false.B)
+  val expected: Vec[Bool] = Vec(false.B, false.B, false.B, false.B, false.B, true.B, true.B, false.B, false.B, true.B)
+
+  dut.io.in := inputs(cycle)
+  assert(dut.io.out === expected(cycle))
+}
+
+class FSMSpec extends CookbookSpec {
+  "DetectTwoOnes" should "work" in {
+    assertTesterPasses { new DetectTwoOnesTester }
+  }
+}