diff --git a/src/fsm.h b/src/fsm.h
new file mode 100644
index 00000000..4a4236ed
--- /dev/null
+++ b/src/fsm.h
@@ -0,0 +1,1024 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_FSM__
+#define __ETL_FSM__
+
+#include <stdint.h>
+
+#include "array.h"
+#include "nullptr.h"
+#include "error_handler.h"
+#include "exception.h"
+#include "user_type.h"
+#include "message_router.h"
+
+#undef ETL_FILE
+#define ETL_FILE "34"
+
+namespace etl
+{
+  /// Allow alternative type for state id.
+#if !defined(ETL_FSM_STATE_ID_TYPE)
+    typedef uint_least8_t fsm_state_id_t;
+#else
+    typedef ETL_FSM_STATE_ID_TYPE fsm_state_id_t;
+#endif
+
+  typedef etl::imessage::id_t fsm_event_id_t;
+
+  //***************************************************************************
+  /// Base exception class for FSM.
+  //***************************************************************************
+  class fsm_exception : public etl::exception
+  {
+  public:
+
+    fsm_exception(string_type what, string_type file_name, numeric_type line_number)
+      : etl::exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Exception for null state pointer.
+  //***************************************************************************
+  class fsm_null_state_exception : public etl::fsm_exception
+  {
+  public:
+
+    fsm_null_state_exception(string_type file_name, numeric_type line_number)
+      : etl::fsm_exception(ETL_ERROR_TEXT("fsm:null state", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Exception for invalid state id.
+  //***************************************************************************
+  class fsm_state_id_exception : public etl::fsm_exception
+  {
+  public:
+
+    fsm_state_id_exception(string_type file_name, numeric_type line_number)
+      : etl::fsm_exception(ETL_ERROR_TEXT("fsm:state id", ETL_FILE"B"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Exception for incompatible state list.
+  //***************************************************************************
+  class fsm_state_list_exception : public etl::fsm_exception
+  {
+  public:
+
+    fsm_state_list_exception(string_type file_name, numeric_type line_number)
+      : etl::fsm_exception(ETL_ERROR_TEXT("fsm:state list", ETL_FILE"C"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Interface class for FSM states.
+  //***************************************************************************
+  class ifsm_state
+  {
+  public:
+
+    friend class fsm;
+
+    //*******************************************
+    /// Gets the id for this state.
+    //*******************************************
+    etl::fsm_state_id_t get_state_id() const
+    {
+      return state_id;
+    }
+
+  protected:
+
+    virtual fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message) = 0;
+
+    //*******************************************
+    /// Constructor.
+    //*******************************************
+    ifsm_state(etl::fsm_state_id_t state_id_)
+      : state_id(state_id_)
+    {
+    }
+
+    virtual void on_enter_state() {}; // By default, do nothing.
+    virtual void on_exit_state() {};  // By default, do nothing.
+
+  private:
+
+    // The state id.
+    const etl::fsm_state_id_t state_id;
+
+    // Disabled.
+    ifsm_state(const ifsm_state&);
+    ifsm_state& operator =(const ifsm_state&);
+  };
+
+  //***************************************************************************
+  class fsm : public etl::imessage_router
+  {
+  public:
+
+    //*******************************************
+    /// Constructor.
+    //*******************************************
+    fsm()
+      : p_state(nullptr)
+    {
+    }
+
+    //*******************************************
+    /// Set the states for the FSM
+    //*******************************************
+    template <typename TSize>
+    void set_states(etl::ifsm_state** p_states, TSize size)
+    {
+      state_list       = p_states;
+      number_of_states = etl::fsm_state_id_t(size);
+
+      for (etl::fsm_state_id_t i = 0; i < size; ++i)
+      {
+        ETL_ASSERT((state_list[i] != nullptr), ETL_ERROR(etl::fsm_null_state_exception));
+      }
+
+      bool ok = (number_of_states > 0) &&
+                etl::is_sorted(state_list, state_list + number_of_states, fsm::CompareStateId());
+
+      ETL_ASSERT(ok, ETL_ERROR(etl::fsm_state_list_exception));
+    }
+
+    //*******************************************
+    /// Starts the FSM.
+    /// Can only be called once.
+    /// Subsequent calls will do nothing.
+    //*******************************************
+    void start()
+    {
+      // Can only be started once.
+      if (p_state == nullptr)
+      {
+        p_state = state_list[0];
+        ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+
+        p_state->on_enter_state();
+      }
+    }
+
+    //*******************************************
+    /// Top level message handlers for the FSM.
+    //*******************************************
+    void receive(const etl::imessage& message)
+    {
+      receive(etl::null_message_router(), message);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& message)
+    {       
+      etl::fsm_state_id_t next_state_id = p_state->process_event(source, message);
+
+      ETL_ASSERT(next_state_id < number_of_states, ETL_ERROR(etl::fsm_state_id_exception));
+
+      // Have we changed state?
+      if (next_state_id != p_state->get_state_id())
+      {
+        p_state->on_exit_state();
+
+        p_state = state_list[next_state_id];
+        ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+
+        p_state->on_enter_state();
+      }
+    }
+
+    //*******************************************
+    /// Gets the current state id.
+    //*******************************************
+    etl::fsm_state_id_t get_state_id() const
+    {
+      ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+      return p_state->get_state_id();
+    }
+
+    //*******************************************
+    /// Gets a reference to the current state interface.
+    //*******************************************
+    ifsm_state& get_state()
+    {
+      ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+      return *p_state;
+    }
+
+    //*******************************************
+    /// Gets a const reference to the current state interface.
+    //*******************************************
+    const ifsm_state& get_state() const
+    {
+      ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+      return *p_state;
+    }
+
+    //*******************************************
+    /// Checks if the FSM has been started.
+    //*******************************************
+    bool is_started() const
+    {
+      return p_state != nullptr;
+    }
+
+    //*******************************************
+    /// Reset the FSM to pre-started state.
+    //*******************************************
+    void reset()
+    {
+      p_state = nullptr;
+    }
+
+  private:
+
+    struct CompareStateId
+    {
+      bool operator()(etl::ifsm_state* lhs, etl::ifsm_state* rhs)
+      {
+        return lhs->get_state_id() < rhs->get_state_id();
+      }
+    };
+
+    etl::ifsm_state*    p_state;          ///< A pointer to the current state.
+    etl::ifsm_state**   state_list;       ///< The list of added states.
+    etl::fsm_state_id_t number_of_states; ///< The number of states.
+  };
+
+  //***************************************************************************
+  // To generate to header file, run this at the command line.
+  // Note: You will need Python and COG installed.
+  //
+  // python -m cogapp -d -e -ofsm.h -DHandlers=<n> fsm_generator.h 
+  // Where <n> is the number of messages to support.
+  //
+  // e.g.
+  // To generate handlers for up to 16 events...
+  // python -m cogapp -d -e -ofsm.h -DHandlers=16 fsm_generator.h 
+  //
+  // See CreateFSM.bat
+  //***************************************************************************
+
+  //***************************************************************************
+  // The code below has been auto generated. Do not manually edit.
+  //***************************************************************************
+
+  //***************************************************************************
+  // The definition for all 16 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1 = void, typename T2 = void, typename T3 = void, typename T4 = void, 
+            typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void, 
+            typename T9 = void, typename T10 = void, typename T11 = void, typename T12 = void, 
+            typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
+  class fsm_state : public ifsm_state
+  {
+  public:
+
+    friend class fsm;
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        case T11::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T11&>(message)); break;
+        case T12::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T12&>(message)); break;
+        case T13::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T13&>(message)); break;
+        case T14::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T14&>(message)); break;
+        case T15::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T15&>(message)); break;
+        case T16::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T16&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 15 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12, 
+            typename T13, typename T14, typename T15>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        case T11::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T11&>(message)); break;
+        case T12::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T12&>(message)); break;
+        case T13::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T13&>(message)); break;
+        case T14::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T14&>(message)); break;
+        case T15::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T15&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 14 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12, 
+            typename T13, typename T14>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        case T11::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T11&>(message)); break;
+        case T12::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T12&>(message)); break;
+        case T13::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T13&>(message)); break;
+        case T14::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T14&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 13 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12, 
+            typename T13>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        case T11::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T11&>(message)); break;
+        case T12::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T12&>(message)); break;
+        case T13::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T13&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 12 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, void, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        case T11::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T11&>(message)); break;
+        case T12::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T12&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 11 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        case T11::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T11&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 10 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        case T10::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T10&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 9 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, T9, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        case T9::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T9&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 8 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, T8, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        case T8::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T8&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 7 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, T4, T5, T6, T7, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        case T7::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T7&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 6 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, T4, T5, T6, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        case T6::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T6&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 5 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, T4, T5, void, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        case T5::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T5&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 4 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3, typename T4>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, T4, void, void, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        case T4::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T4&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 3 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2, typename T3>
+  class fsm_state<TState, STATE_ID_, T1, T2, T3, void, void, void, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        case T3::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T3&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 2 message types.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1, typename T2>
+  class fsm_state<TState, STATE_ID_, T1, T2, void, void, void, void, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        case T2::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T2&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 1 message type.
+  //***************************************************************************
+  template <typename TState, const etl::fsm_state_id_t STATE_ID_, 
+            typename T1>
+  class fsm_state<TState, STATE_ID_, T1, void, void, void, void, void, void, void, void, void, void, void, void, void, void, void> : public ifsm_state
+  {
+  public:
+    friend class fsm;
+
+
+    enum
+    {
+      STATE_ID = STATE_ID_
+    };
+
+    fsm_state()
+      : ifsm_state(STATE_ID)
+    {
+    }
+
+    etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)
+    {
+      etl::fsm_state_id_t new_state_id;
+      etl::fsm_event_id_t event_id = message.get_message_id();
+
+      switch (event_id)
+      {
+        case T1::ID: new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T1&>(message)); break;
+        default: new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message); break;
+      }
+
+      return new_state_id;
+    }
+  };
+}
+
+#undef ETL_FILE
+
+#endif
\ No newline at end of file
diff --git a/src/fsm_generator.h b/src/fsm_generator.h
new file mode 100644
index 00000000..624bc856
--- /dev/null
+++ b/src/fsm_generator.h
@@ -0,0 +1,428 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_FSM__
+#define __ETL_FSM__
+
+#include <stdint.h>
+
+#include "array.h"
+#include "nullptr.h"
+#include "error_handler.h"
+#include "exception.h"
+#include "user_type.h"
+#include "message_router.h"
+
+#undef ETL_FILE
+#define ETL_FILE "34"
+
+namespace etl
+{
+  /// Allow alternative type for state id.
+#if !defined(ETL_FSM_STATE_ID_TYPE)
+    typedef uint_least8_t fsm_state_id_t;
+#else
+    typedef ETL_FSM_STATE_ID_TYPE fsm_state_id_t;
+#endif
+
+  typedef etl::imessage::id_t fsm_event_id_t;
+
+  //***************************************************************************
+  /// Base exception class for FSM.
+  //***************************************************************************
+  class fsm_exception : public etl::exception
+  {
+  public:
+
+    fsm_exception(string_type what, string_type file_name, numeric_type line_number)
+      : etl::exception(what, file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Exception for null state pointer.
+  //***************************************************************************
+  class fsm_null_state_exception : public etl::fsm_exception
+  {
+  public:
+
+    fsm_null_state_exception(string_type file_name, numeric_type line_number)
+      : etl::fsm_exception(ETL_ERROR_TEXT("fsm:null state", ETL_FILE"A"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Exception for invalid state id.
+  //***************************************************************************
+  class fsm_state_id_exception : public etl::fsm_exception
+  {
+  public:
+
+    fsm_state_id_exception(string_type file_name, numeric_type line_number)
+      : etl::fsm_exception(ETL_ERROR_TEXT("fsm:state id", ETL_FILE"B"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Exception for incompatible state list.
+  //***************************************************************************
+  class fsm_state_list_exception : public etl::fsm_exception
+  {
+  public:
+
+    fsm_state_list_exception(string_type file_name, numeric_type line_number)
+      : etl::fsm_exception(ETL_ERROR_TEXT("fsm:state list", ETL_FILE"C"), file_name, line_number)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Interface class for FSM states.
+  //***************************************************************************
+  class ifsm_state
+  {
+  public:
+
+    friend class fsm;
+
+    //*******************************************
+    /// Gets the id for this state.
+    //*******************************************
+    etl::fsm_state_id_t get_state_id() const
+    {
+      return state_id;
+    }
+
+  protected:
+
+    virtual fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message) = 0;
+
+    //*******************************************
+    /// Constructor.
+    //*******************************************
+    ifsm_state(etl::fsm_state_id_t state_id_)
+      : state_id(state_id_)
+    {
+    }
+
+    virtual void on_enter_state() {}; // By default, do nothing.
+    virtual void on_exit_state() {};  // By default, do nothing.
+
+  private:
+
+    // The state id.
+    const etl::fsm_state_id_t state_id;
+
+    // Disabled.
+    ifsm_state(const ifsm_state&);
+    ifsm_state& operator =(const ifsm_state&);
+  };
+
+  //***************************************************************************
+  class fsm : public etl::imessage_router
+  {
+  public:
+
+    //*******************************************
+    /// Constructor.
+    //*******************************************
+    fsm()
+      : p_state(nullptr)
+    {
+    }
+
+    //*******************************************
+    /// Set the states for the FSM
+    //*******************************************
+    template <typename TSize>
+    void set_states(etl::ifsm_state** p_states, TSize size)
+    {
+      state_list       = p_states;
+      number_of_states = etl::fsm_state_id_t(size);
+
+      for (etl::fsm_state_id_t i = 0; i < size; ++i)
+      {
+        ETL_ASSERT((state_list[i] != nullptr), ETL_ERROR(etl::fsm_null_state_exception));
+      }
+
+      bool ok = (number_of_states > 0) &&
+                etl::is_sorted(state_list, state_list + number_of_states, fsm::CompareStateId());
+
+      ETL_ASSERT(ok, ETL_ERROR(etl::fsm_state_list_exception));
+    }
+
+    //*******************************************
+    /// Starts the FSM.
+    /// Can only be called once.
+    /// Subsequent calls will do nothing.
+    //*******************************************
+    void start()
+    {
+      // Can only be started once.
+      if (p_state == nullptr)
+      {
+        p_state = state_list[0];
+        ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+
+        p_state->on_enter_state();
+      }
+    }
+
+    //*******************************************
+    /// Top level message handlers for the FSM.
+    //*******************************************
+    void receive(const etl::imessage& message)
+    {
+      receive(etl::null_message_router(), message);
+    }
+
+    void receive(etl::imessage_router& source, const etl::imessage& message)
+    {       
+      etl::fsm_state_id_t next_state_id = p_state->process_event(source, message);
+
+      ETL_ASSERT(next_state_id < number_of_states, ETL_ERROR(etl::fsm_state_id_exception));
+
+      // Have we changed state?
+      if (next_state_id != p_state->get_state_id())
+      {
+        p_state->on_exit_state();
+
+        p_state = state_list[next_state_id];
+        ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+
+        p_state->on_enter_state();
+      }
+    }
+
+    //*******************************************
+    /// Gets the current state id.
+    //*******************************************
+    etl::fsm_state_id_t get_state_id() const
+    {
+      ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+      return p_state->get_state_id();
+    }
+
+    //*******************************************
+    /// Gets a reference to the current state interface.
+    //*******************************************
+    ifsm_state& get_state()
+    {
+      ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+      return *p_state;
+    }
+
+    //*******************************************
+    /// Gets a const reference to the current state interface.
+    //*******************************************
+    const ifsm_state& get_state() const
+    {
+      ETL_ASSERT(p_state != nullptr, ETL_ERROR(etl::fsm_null_state_exception));
+      return *p_state;
+    }
+
+    //*******************************************
+    /// Checks if the FSM has been started.
+    //*******************************************
+    bool is_started() const
+    {
+      return p_state != nullptr;
+    }
+
+    //*******************************************
+    /// Reset the FSM to pre-started state.
+    //*******************************************
+    void reset()
+    {
+      p_state = nullptr;
+    }
+
+  private:
+
+    struct CompareStateId
+    {
+      bool operator()(etl::ifsm_state* lhs, etl::ifsm_state* rhs)
+      {
+        return lhs->get_state_id() < rhs->get_state_id();
+      }
+    };
+
+    etl::ifsm_state*    p_state;          ///< A pointer to the current state.
+    etl::ifsm_state**   state_list;       ///< The list of added states.
+    etl::fsm_state_id_t number_of_states; ///< The number of states.
+  };
+
+  //***************************************************************************
+  // To generate to header file, run this at the command line.
+  // Note: You will need Python and COG installed.
+  //
+  // python -m cogapp -d -e -ofsm.h -DHandlers=<n> fsm_generator.h 
+  // Where <n> is the number of messages to support.
+  //
+  // e.g.
+  // To generate handlers for up to 16 events...
+  // python -m cogapp -d -e -ofsm.h -DHandlers=16 fsm_generator.h 
+  //
+  // See CreateFSM.bat
+  //***************************************************************************
+
+  /*[[[cog
+  import cog
+  cog.outl("//***************************************************************************")
+  cog.outl("// The code below has been auto generated. Do not manually edit.")
+  cog.outl("//***************************************************************************")
+  cog.outl("")
+  ################################################
+  # The first definition for all of the events.
+  ################################################
+  cog.outl("//***************************************************************************")
+  cog.outl("// The definition for all %s message types." % Handlers)
+  cog.outl("//***************************************************************************")
+  cog.outl("template <typename TState, const etl::fsm_state_id_t STATE_ID_, ")
+  cog.out("          ")
+  for n in range(1, int(Handlers)):
+      cog.out("typename T%s = void, " % n)
+      if n % 4 == 0:
+          cog.outl("")
+          cog.out("          ")
+  cog.outl("typename T%s = void>" % Handlers)
+  cog.outl("class fsm_state : public ifsm_state")
+  cog.outl("{")
+  cog.outl("public:")
+  cog.outl("")
+
+  cog.outl("  friend class fsm;")
+  cog.outl("")
+
+  cog.outl("  enum")
+  cog.outl("  {")
+  cog.outl("    STATE_ID = STATE_ID_")
+  cog.outl("  };")
+  cog.outl("")
+  cog.outl("  fsm_state()")
+  cog.outl("    : ifsm_state(STATE_ID)")
+  cog.outl("  {")
+  cog.outl("  }")
+  cog.outl("")
+  cog.outl("  etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)")
+  cog.outl("  {")
+  cog.outl("    etl::fsm_state_id_t new_state_id;")
+  cog.outl("    etl::fsm_event_id_t event_id = message.get_message_id();")
+  cog.outl("")
+  cog.outl("    switch (event_id)")
+  cog.outl("    {")
+  for n in range(1, int(Handlers) + 1):
+      cog.out("      case T%d::ID:" % n)
+      cog.out(" new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T%d&>(message));" % n)
+      cog.outl(" break;")
+  cog.out("      default:")
+  cog.out(" new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message);")
+  cog.outl(" break;")
+  cog.outl("    }")
+  cog.outl("")
+  cog.outl("    return new_state_id;")
+  cog.outl("  }")
+  cog.outl("};")
+
+  ####################################
+  # All of the other specialisations.
+  ####################################
+  for n in range(int(Handlers) - 1, 0, -1):
+      cog.outl("")
+      cog.outl("//***************************************************************************")
+      if n == 1:
+          cog.outl("// Specialisation for %d message type." % n)
+      else:
+          cog.outl("// Specialisation for %d message types." % n)
+      cog.outl("//***************************************************************************")
+      cog.outl("template <typename TState, const etl::fsm_state_id_t STATE_ID_, ")
+      cog.out("          ")
+      for t in range(1, n):
+          cog.out("typename T%d, " % t)
+          if t % 4 == 0:
+              cog.outl("")
+              cog.out("          ")
+      cog.outl("typename T%d>" % n)
+      cog.out("class fsm_state<TState, STATE_ID_, ")
+      for t in range(1, n + 1):
+          cog.out("T%d, " % t)
+      if t % 16 == 0:
+          cog.outl("")
+          cog.out("               ")
+      for t in range(n + 1, int(Handlers)):
+          cog.out("void, ")
+      if t % 16 == 0:
+          cog.outl("")
+          cog.out("               ")
+      cog.outl("void> : public ifsm_state")
+      cog.outl("{")
+      cog.outl("public:")
+
+      cog.outl("  friend class fsm;")
+      cog.outl("")
+
+      cog.outl("")
+      cog.outl("  enum")
+      cog.outl("  {")
+      cog.outl("    STATE_ID = STATE_ID_")
+      cog.outl("  };")
+      cog.outl("")
+      cog.outl("  fsm_state()")
+      cog.outl("    : ifsm_state(STATE_ID)")
+      cog.outl("  {")
+      cog.outl("  }")
+      cog.outl("")
+      cog.outl("  etl::fsm_state_id_t process_event(etl::imessage_router& source, const etl::imessage& message)")
+      cog.outl("  {")
+      cog.outl("    etl::fsm_state_id_t new_state_id;")
+      cog.outl("    etl::fsm_event_id_t event_id = message.get_message_id();")
+      cog.outl("")
+      cog.outl("    switch (event_id)")
+      cog.outl("    {")
+      for n in range(1, n + 1):
+          cog.out("      case T%d::ID:" % n)
+          cog.out(" new_state_id = static_cast<TState*>(this)->on_event(source, static_cast<const T%d&>(message));" % n)
+          cog.outl(" break;")
+      cog.out("      default:")
+      cog.out(" new_state_id = static_cast<TState*>(this)->on_event_unknown(source, message);")
+      cog.outl(" break;")
+      cog.outl("    }")
+      cog.outl("")
+      cog.outl("    return new_state_id;")
+      cog.outl("  }")
+      cog.outl("};")
+  ]]]*/
+  /*[[[end]]]*/
+}
+
+#undef ETL_FILE
+
+#endif
\ No newline at end of file
diff --git a/src/message_router.h b/src/message_router.h
new file mode 100644
index 00000000..057d7efb
--- /dev/null
+++ b/src/message_router.h
@@ -0,0 +1,715 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_MESSAGE_ROUTER__
+#define __ETL_MESSAGE_ROUTER__
+
+#include <stdint.h>
+
+namespace etl
+{
+  //***************************************************************************
+  class imessage
+  {
+  public:
+
+  /// Allow alternative type for message id.
+#if !defined(ETL_MESSAGE_ID_TYPE)
+    typedef uint_least8_t id_t;
+#else
+    typedef ETL_MESSAGE_ID_TYPE id_t;
+#endif
+
+    virtual ~imessage() {}
+    virtual id_t get_message_id() const = 0;
+  };
+
+  //***************************************************************************
+  template <const size_t ID_>
+  class message : public imessage
+  {
+  public:
+
+    enum
+    {
+      ID = ID_
+    };
+
+    id_t get_message_id() const
+    {
+      return id_t(ID);
+    }
+  };
+
+  //***************************************************************************
+  class imessage_router
+  {
+  public:
+    virtual ~imessage_router() {}
+    virtual void receive(const imessage& message) = 0;
+    virtual void receive(imessage_router& source, const imessage& message) = 0;
+
+    void send_message(imessage_router& destination,
+                      const imessage&  message)
+    {
+      destination.receive(*this, message);
+    }
+  };
+
+  //***************************************************************************
+  /// This router can be used either as a sink for messages
+  /// or as a producer-only of messages such an interrupt routine.
+  //***************************************************************************
+  class null_message_router : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& message)
+    {
+    }
+
+    void receive(imessage_router& source, const imessage& message)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Send a message to a router.
+  /// Sets the 'sender' to etl::null_message_router type.
+  //***************************************************************************
+  inline static void send_message(imessage_router& destination, 
+                                  const imessage&  message)
+  {
+    destination.receive(message);
+  }
+
+  //***************************************************************************
+  /// Send a message to a router.
+  //***************************************************************************
+  inline static void send_message(imessage_router& source, 
+                                  imessage_router& destination, 
+                                  const imessage&  message)
+  {
+    destination.receive(source, message);
+  }
+  
+  //***************************************************************************
+  // To generate to header file, run this at the command line.
+  // Note: You will need Python and COG installed.
+  //
+  // python -m cogapp -d -e -omessage_router.h -DHandlers=<n> message_router_generator.h 
+  // Where <n> is the number of messages to support.
+  //
+  // e.g.
+  // To generate handlers for up to 16 messages...
+  // python -m cogapp -d -e -omessage_router.h -DHandlers=16 message_router_generator.h 
+  //
+  // See CreateMessageProcessor.bat
+  //***************************************************************************
+
+  //***************************************************************************
+  // The code below has been auto generated. Do not manually edit.
+  //***************************************************************************
+
+  //***************************************************************************
+  // The definition for all 16 message types.
+  //***************************************************************************
+  template <typename TProcessor,
+            typename T1, typename T2 = void, typename T3 = void, typename T4 = void, 
+            typename T5 = void, typename T6 = void, typename T7 = void, typename T8 = void, 
+            typename T9 = void, typename T10 = void, typename T11 = void, typename T12 = void, 
+            typename T13 = void, typename T14 = void, typename T15 = void, typename T16 = void>
+  class message_router  : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const id_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        case T13::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T13&>(msg)); break;
+        case T14::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T14&>(msg)); break;
+        case T15::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T15&>(msg)); break;
+        case T16::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T16&>(msg)); break;
+        default:  static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 15 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12, 
+            typename T13, typename T14, typename T15>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        case T13::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T13&>(msg)); break;
+        case T14::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T14&>(msg)); break;
+        case T15::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T15&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 14 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12, 
+            typename T13, typename T14>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        case T13::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T13&>(msg)); break;
+        case T14::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T14&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 13 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12, 
+            typename T13>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        case T13::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T13&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 12 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11, typename T12>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        case T12::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T12&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 11 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10, typename T11>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        case T11::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T11&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 10 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9, typename T10>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        case T10::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T10&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 9 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8, 
+            typename T9>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, T9, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        case T9::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T9&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 8 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7, typename T8>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, T8, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        case T8::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T8&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 7 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6, typename T7>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, T7, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        case T7::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T7&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 6 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5, typename T6>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, T6, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        case T6::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T6&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 5 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3, typename T4, 
+            typename T5>
+  class message_router<TProcessor, T1, T2, T3, T4, T5, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        case T5::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T5&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 4 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3, typename T4>
+  class message_router<TProcessor, T1, T2, T3, T4, void, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        case T4::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T4&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 3 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2, typename T3>
+  class message_router<TProcessor, T1, T2, T3, void, void, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        case T3::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T3&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 2 message types.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1, typename T2>
+  class message_router<TProcessor, T1, T2, void, void, void, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        case T2::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T2&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+
+  //***************************************************************************
+  // Specialisation for 1 message type.
+  //***************************************************************************
+  template <typename TProcessor, 
+            typename T1>
+  class message_router<TProcessor, T1, void, void, void, void, void, void, void, void, void, void, void, void, void, void, void>
+   : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& msg)
+    {
+      receive(etl::null_message_router(), msg);
+    }
+
+    void receive(imessage_router& source, const imessage& msg)
+    {
+      const size_t id = msg.get_message_id();
+
+      switch (id)
+      {
+        case T1::ID: static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T1&>(msg)); break;
+        default: static_cast<TProcessor*>(this)->on_receive_unknown(source, msg); break;
+      }
+    }
+  };
+}
+
+#endif
diff --git a/src/message_router_generator.h b/src/message_router_generator.h
new file mode 100644
index 00000000..85fa2021
--- /dev/null
+++ b/src/message_router_generator.h
@@ -0,0 +1,243 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#ifndef __ETL_MESSAGE_ROUTER__
+#define __ETL_MESSAGE_ROUTER__
+
+#include <stdint.h>
+
+namespace etl
+{
+  //***************************************************************************
+  class imessage
+  {
+  public:
+
+  /// Allow alternative type for message id.
+#if !defined(ETL_MESSAGE_ID_TYPE)
+    typedef uint_least8_t id_t;
+#else
+    typedef ETL_MESSAGE_ID_TYPE id_t;
+#endif
+
+    virtual ~imessage() {}
+    virtual id_t get_message_id() const = 0;
+  };
+
+  //***************************************************************************
+  template <const size_t ID_>
+  class message : public imessage
+  {
+  public:
+
+    enum
+    {
+      ID = ID_
+    };
+
+    id_t get_message_id() const
+    {
+      return id_t(ID);
+    }
+  };
+
+  //***************************************************************************
+  class imessage_router
+  {
+  public:
+    virtual ~imessage_router() {}
+    virtual void receive(const imessage& message) = 0;
+    virtual void receive(imessage_router& source, const imessage& message) = 0;
+
+    void send_message(imessage_router& destination,
+                      const imessage&  message)
+    {
+      destination.receive(*this, message);
+    }
+  };
+
+  //***************************************************************************
+  /// This router can be used either as a sink for messages
+  /// or as a producer-only of messages such an interrupt routine.
+  //***************************************************************************
+  class null_message_router : public imessage_router
+  {
+  public:
+
+    void receive(const imessage& message)
+    {
+    }
+
+    void receive(imessage_router& source, const imessage& message)
+    {
+    }
+  };
+
+  //***************************************************************************
+  /// Send a message to a router.
+  /// Sets the 'sender' to etl::null_message_router type.
+  //***************************************************************************
+  inline static void send_message(imessage_router& destination, 
+                                  const imessage&  message)
+  {
+    destination.receive(message);
+  }
+
+  //***************************************************************************
+  /// Send a message to a router.
+  //***************************************************************************
+  inline static void send_message(imessage_router& source, 
+                                  imessage_router& destination, 
+                                  const imessage&  message)
+  {
+    destination.receive(source, message);
+  }
+  
+  //***************************************************************************
+  // To generate to header file, run this at the command line.
+  // Note: You will need Python and COG installed.
+  //
+  // python -m cogapp -d -e -omessage_router.h -DHandlers=<n> message_router_generator.h 
+  // Where <n> is the number of messages to support.
+  //
+  // e.g.
+  // To generate handlers for up to 16 messages...
+  // python -m cogapp -d -e -omessage_router.h -DHandlers=16 message_router_generator.h 
+  //
+  // See CreateMessageProcessor.bat
+  //***************************************************************************
+
+  /*[[[cog
+      import cog
+      cog.outl("//***************************************************************************")
+      cog.outl("// The code below has been auto generated. Do not manually edit.")
+      cog.outl("//***************************************************************************")
+      cog.outl("")
+      ################################################
+      # The first definition for all of the messages.
+      ################################################
+      cog.outl("//***************************************************************************")
+      cog.outl("// The definition for all %s message types." % Handlers)
+      cog.outl("//***************************************************************************")
+      cog.outl("template <typename TProcessor,")
+      cog.out("          ")
+      cog.out("typename T1, ")
+      for n in range(2, int(Handlers)):
+          cog.out("typename T%s = void, " % n)
+          if n % 4 == 0:
+              cog.outl("")
+              cog.out("          ")
+      cog.outl("typename T%s = void>" % Handlers)
+      cog.out("class message_router")
+      cog.outl("  : public imessage_router")
+      cog.outl("{")
+      cog.outl("public:")
+      cog.outl("")
+      cog.outl("  void receive(const imessage& msg)")
+      cog.outl("  {")
+      cog.outl("    receive(etl::null_message_router(), msg);")
+      cog.outl("  }")
+      cog.outl("")
+      cog.outl("  void receive(imessage_router& source, const imessage& msg)")
+      cog.outl("  {")
+      cog.outl("    const id_t id = msg.get_message_id();")
+      cog.outl("")
+      cog.outl("    switch (id)")
+      cog.outl("    {")
+      for n in range(1, int(Handlers) + 1):
+          cog.out("      case T%d::ID:" % n)
+          cog.out(" static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T%d&>(msg));" % n)
+          cog.outl(" break;")
+      cog.out("      default:")
+      cog.out("  static_cast<TProcessor*>(this)->on_receive_unknown(source, msg);")
+      cog.outl(" break;")
+      cog.outl("    }")
+      cog.outl("  }")
+      cog.outl("};")
+
+      ####################################
+      # All of the other specialisations.
+      ####################################
+      for n in range(int(Handlers) - 1, 0, -1):
+          cog.outl("")
+          cog.outl("//***************************************************************************")
+          if n == 1:
+              cog.outl("// Specialisation for %d message type." % n)
+          else:
+              cog.outl("// Specialisation for %d message types." % n)
+          cog.outl("//***************************************************************************")
+          cog.outl("template <typename TProcessor, ")
+          cog.out("          ")
+          for t in range(1, n):
+              cog.out("typename T%d, " % t)
+              if t % 4 == 0:
+                  cog.outl("")
+                  cog.out("          ")
+          cog.outl("typename T%d>" % n)
+          cog.out("class message_router<TProcessor, ")
+          for t in range(1, n + 1):
+              cog.out("T%d, " % t)
+              if t % 16 == 0:
+                  cog.outl("")
+                  cog.out("               ")
+          for t in range(n + 1, int(Handlers)):
+              cog.out("void, ")
+              if t % 16 == 0:
+                  cog.outl("")
+                  cog.out("               ")
+          cog.outl("void>")
+          cog.outl(" : public imessage_router")
+          cog.outl("{")
+          cog.outl("public:")
+          cog.outl("")
+          cog.outl("  void receive(const imessage& msg)")
+          cog.outl("  {")
+          cog.outl("    receive(etl::null_message_router(), msg);")
+          cog.outl("  }")
+          cog.outl("")
+          cog.outl("  void receive(imessage_router& source, const imessage& msg)")
+          cog.outl("  {")
+          cog.outl("    const size_t id = msg.get_message_id();")
+          cog.outl("")
+          cog.outl("    switch (id)")
+          cog.outl("    {")
+          for t in range(1, n + 1):
+              cog.out("      case T%d::ID:" % t)
+              cog.out(" static_cast<TProcessor*>(this)->on_receive(source, static_cast<const T%d&>(msg));" % t)
+              cog.outl(" break;")
+          cog.out("      default:")
+          cog.out(" static_cast<TProcessor*>(this)->on_receive_unknown(source, msg);")
+          cog.outl(" break;")
+          cog.outl("    }")
+          cog.outl("  }")
+          cog.outl("};")
+  ]]]*/
+  /*[[[end]]]*/
+}
+
+#endif
diff --git a/test/test_fsm.cpp b/test/test_fsm.cpp
new file mode 100644
index 00000000..2c2420b6
--- /dev/null
+++ b/test/test_fsm.cpp
@@ -0,0 +1,498 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+https://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#include "UnitTest++.h"
+
+#include "fsm.h"
+#include "enum_type.h"
+#include "container.h"
+
+#include <iostream>
+
+namespace
+{
+  //***************************************************************************
+  // Events
+  struct EventId
+  {
+    enum enum_type
+    {
+      START,
+      STOP,
+      STOPPED,
+      SET_SPEED
+    };
+
+    ETL_DECLARE_ENUM_TYPE(EventId, etl::fsm_event_id_t)
+    ETL_ENUM_TYPE(START,     "Start")
+    ETL_ENUM_TYPE(STOP,      "Stop")
+    ETL_ENUM_TYPE(STOPPED,   "Stopped")
+    ETL_ENUM_TYPE(SET_SPEED, "Set Speed")
+    ETL_END_ENUM_TYPE
+  };
+
+  //***********************************
+  class Start : public etl::message<EventId::START>
+  {
+  };
+
+  //***********************************
+  class Stop : public etl::message<EventId::STOP>
+  {
+  public:
+
+    Stop() : isEmergencyStop(false) {}
+    Stop(bool emergency) : isEmergencyStop(emergency) {}
+
+    const bool isEmergencyStop;
+  };
+
+  //***********************************
+  class SetSpeed : public etl::message<EventId::SET_SPEED>
+  {
+  public:
+
+    SetSpeed(int speed) : speed(speed) {}
+
+    const int speed;
+  };
+
+  //***********************************
+  class Stopped : public etl::message<EventId::STOPPED>
+  {
+  };
+
+  //***************************************************************************
+  // States
+  struct StateId
+  {
+    enum enum_type
+    {
+      IDLE,
+      RUNNING,
+      WINDING_DOWN,
+      NUMBER_OF_STATES
+    };
+
+    ETL_DECLARE_ENUM_TYPE(StateId, etl::fsm_state_id_t)
+    ETL_ENUM_TYPE(IDLE,         "Idle")
+    ETL_ENUM_TYPE(RUNNING,      "Running")
+    ETL_ENUM_TYPE(WINDING_DOWN, "Winding Down")
+    ETL_END_ENUM_TYPE
+  };
+
+  class MotorControl;
+
+  //***********************************
+  // Common functionality
+  //***********************************
+  class Common
+  {
+  public:
+
+    //***********************************
+    Common()
+    {
+      ClearStatistics();
+    }
+
+    //***********************************
+    void ClearStatistics()
+    {
+      startCount    = 0;
+      stopCount     = 0;
+      setSpeedCount = 0;
+      unknownCount  = 0;
+      stoppedCount  = 0;
+      isLampOn      = false;
+      speed         = 0;
+    }
+
+    //***********************************
+    void SetSpeed(int speed_)
+    {
+      speed = speed_;
+    }
+
+    //***********************************
+    void TurnRunningLampOn()
+    {
+      isLampOn = true;
+    }
+
+    //***********************************
+    void TurnRunningLampOff()
+    {
+      isLampOn = false;
+    }
+
+    int startCount;
+    int stopCount;
+    int setSpeedCount;
+    int unknownCount;
+    int stoppedCount;
+    bool isLampOn;
+    int speed;
+  };
+
+  //***********************************
+  // The idle state.
+  //***********************************
+  class Idle : public etl::fsm_state<Idle, StateId::IDLE, Start>
+  {
+  public:
+
+    //***********************************
+    Idle(Common& common)
+      : common(common)
+    {
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_event(etl::imessage_router& sender, const Start& event)
+    {
+      ++common.startCount;
+      return StateId::RUNNING;
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_event_unknown(etl::imessage_router& sender, const etl::imessage& event)
+    {
+      ++common.unknownCount;
+      return STATE_ID;
+    }
+
+    //***********************************
+    void on_enter_state()
+    {
+      common.TurnRunningLampOff();
+    }
+
+    Common& common;
+  };
+
+  //***********************************
+  // The running state.
+  //***********************************
+  class Running : public etl::fsm_state<Running, StateId::RUNNING, Stop, SetSpeed>
+  {
+  public:
+
+    //***********************************
+    Running(Common& common)
+      : common(common)
+    {
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_event(etl::imessage_router& sender, const Stop& event)
+    {
+      ++common.stopCount;
+
+      if (event.isEmergencyStop)
+      {
+        return StateId::IDLE;
+      }
+      else
+      {
+        return StateId::WINDING_DOWN;
+      }
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_event(etl::imessage_router& sender, const SetSpeed& event)
+    {
+      ++common.setSpeedCount;
+      common.SetSpeed(event.speed);
+      return STATE_ID;
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_event_unknown(etl::imessage_router& sender, const etl::imessage& event)
+    {
+      ++common.unknownCount;
+      return STATE_ID;
+    }
+
+    void on_enter_state()
+    {
+      common.TurnRunningLampOn();
+    }
+
+    Common& common;
+  };
+
+  //***********************************
+  // The winding down state.
+  //***********************************
+  class WindingDown : public etl::fsm_state<WindingDown, StateId::WINDING_DOWN, Stopped>
+  {
+  public:
+
+    //***********************************
+    WindingDown(Common& common)
+      : common(common)
+    {
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_event(etl::imessage_router& source, const Stopped& event)
+    {
+      ++common.stoppedCount;
+      return StateId::IDLE;
+    }
+
+    //***********************************
+    etl::fsm_state_id_t on_event_unknown(etl::imessage_router& source, const etl::imessage& event)
+    {
+      ++common.unknownCount;
+      return STATE_ID;
+    }
+
+    Common& common;
+  };
+
+  //***********************************
+  // The motor control FSM.
+  //***********************************
+  class MotorControl : public etl::fsm
+  {
+  public:
+
+    MotorControl()
+      : idle(common),
+        running(common),
+        windingDown(common)
+    {
+      set_states(stateList, etl::size(stateList));
+    }
+
+    Common common;
+
+  private:
+
+    // The states.
+    Idle        idle;
+    Running     running;
+    WindingDown windingDown;
+
+    etl::ifsm_state* stateList[StateId::NUMBER_OF_STATES] =
+    {
+      &idle, &running, &windingDown
+    };
+  };
+
+  MotorControl motorControl;
+
+  SUITE(test_map)
+  {
+    //*************************************************************************
+    TEST(test_fsm)
+    {
+      motorControl.reset();
+      motorControl.common.ClearStatistics();
+
+      CHECK(!motorControl.is_started());
+
+      // Start the FSM.
+      motorControl.start();
+      CHECK(motorControl.is_started());
+
+      // Now in Idle state.
+
+      CHECK_EQUAL(StateId::IDLE, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::IDLE, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(false, motorControl.common.isLampOn);
+      CHECK_EQUAL(0, motorControl.common.setSpeedCount);
+      CHECK_EQUAL(0, motorControl.common.speed);
+      CHECK_EQUAL(0, motorControl.common.startCount);
+      CHECK_EQUAL(0, motorControl.common.stopCount);
+      CHECK_EQUAL(0, motorControl.common.stoppedCount);
+      CHECK_EQUAL(0, motorControl.common.unknownCount);
+
+      // Send unhandled events.
+      motorControl.receive(etl::null_message_router(), Stop());
+      motorControl.receive(etl::null_message_router(), Stopped());
+      motorControl.receive(etl::null_message_router(), SetSpeed(10));
+
+      CHECK_EQUAL(StateId::IDLE, motorControl.get_state_id());
+      CHECK_EQUAL(StateId::IDLE, motorControl.get_state().get_state_id());
+
+      CHECK_EQUAL(false, motorControl.common.isLampOn);
+      CHECK_EQUAL(0, motorControl.common.setSpeedCount);
+      CHECK_EQUAL(0, motorControl.common.speed);
+      CHECK_EQUAL(0, motorControl.common.startCount);
+      CHECK_EQUAL(0, motorControl.common.stopCount);
+      CHECK_EQUAL(0, motorControl.common.stoppedCount);
+      CHECK_EQUAL(3, motorControl.common.unknownCount);
+
+      // Send Start event.
+      motorControl.receive(etl::null_message_router(), Start());
+
+      // Now in Running state.
+
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(true, motorControl.common.isLampOn);
+      CHECK_EQUAL(0, motorControl.common.setSpeedCount);
+      CHECK_EQUAL(0, motorControl.common.speed);
+      CHECK_EQUAL(1, motorControl.common.startCount);
+      CHECK_EQUAL(0, motorControl.common.stopCount);
+      CHECK_EQUAL(0, motorControl.common.stoppedCount);
+      CHECK_EQUAL(3, motorControl.common.unknownCount);
+
+      // Send unhandled events.
+      motorControl.receive(etl::null_message_router(), Start());
+      motorControl.receive(etl::null_message_router(), Stopped());
+
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(true, motorControl.common.isLampOn);
+      CHECK_EQUAL(0, motorControl.common.setSpeedCount);
+      CHECK_EQUAL(0, motorControl.common.speed);
+      CHECK_EQUAL(1, motorControl.common.startCount);
+      CHECK_EQUAL(0, motorControl.common.stopCount);
+      CHECK_EQUAL(0, motorControl.common.stoppedCount);
+      CHECK_EQUAL(5, motorControl.common.unknownCount);
+
+      // Send SetSpeed event.
+      motorControl.receive(etl::null_message_router(), SetSpeed(100));
+
+      // Still in Running state.
+
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(true, motorControl.common.isLampOn);
+      CHECK_EQUAL(1, motorControl.common.setSpeedCount);
+      CHECK_EQUAL(100, motorControl.common.speed);
+      CHECK_EQUAL(1, motorControl.common.startCount);
+      CHECK_EQUAL(0, motorControl.common.stopCount);
+      CHECK_EQUAL(0, motorControl.common.stoppedCount);
+      CHECK_EQUAL(5, motorControl.common.unknownCount);
+
+      // Send Stop event.
+      motorControl.receive(etl::null_message_router(), Stop());
+
+      // Now in WindingDown state.
+
+      CHECK_EQUAL(StateId::WINDING_DOWN, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::WINDING_DOWN, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(true, motorControl.common.isLampOn);
+      CHECK_EQUAL(1, motorControl.common.setSpeedCount);
+      CHECK_EQUAL(100, motorControl.common.speed);
+      CHECK_EQUAL(1, motorControl.common.startCount);
+      CHECK_EQUAL(1, motorControl.common.stopCount);
+      CHECK_EQUAL(0, motorControl.common.stoppedCount);
+      CHECK_EQUAL(5, motorControl.common.unknownCount);
+
+      // Send unhandled events.
+      motorControl.receive(etl::null_message_router(), Start());
+      motorControl.receive(etl::null_message_router(), Stop());
+      motorControl.receive(etl::null_message_router(), SetSpeed(100));
+
+      CHECK_EQUAL(StateId::WINDING_DOWN, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::WINDING_DOWN, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(true, motorControl.common.isLampOn);
+      CHECK_EQUAL(1, motorControl.common.setSpeedCount);
+      CHECK_EQUAL(100, motorControl.common.speed);
+      CHECK_EQUAL(1, motorControl.common.startCount);
+      CHECK_EQUAL(1, motorControl.common.stopCount);
+      CHECK_EQUAL(0, motorControl.common.stoppedCount);
+      CHECK_EQUAL(8, motorControl.common.unknownCount);
+
+      // Send Stopped event.
+      motorControl.receive(etl::null_message_router(), Stopped());
+
+      // Now in Idle state.
+
+      CHECK_EQUAL(StateId::IDLE, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::IDLE, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(false, motorControl.common.isLampOn);
+      CHECK_EQUAL(1, motorControl.common.setSpeedCount);
+      CHECK_EQUAL(100, motorControl.common.speed);
+      CHECK_EQUAL(1, motorControl.common.startCount);
+      CHECK_EQUAL(1, motorControl.common.stopCount);
+      CHECK_EQUAL(1, motorControl.common.stoppedCount);
+      CHECK_EQUAL(8, motorControl.common.unknownCount);
+    }
+
+    //*************************************************************************
+    TEST(test_fsm_emergency_stop)
+    {
+      motorControl.reset();
+      motorControl.common.ClearStatistics();
+
+      CHECK(!motorControl.is_started());
+
+      // Start the FSM.
+      motorControl.start();
+      CHECK(motorControl.is_started());
+
+      // Now in Idle state.
+
+      // Send Start event.
+      motorControl.receive(etl::null_message_router(), Start());
+
+      // Now in Running state.
+
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::RUNNING, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(true, motorControl.common.isLampOn);
+      CHECK_EQUAL(0, motorControl.common.setSpeedCount);
+      CHECK_EQUAL(0, motorControl.common.speed);
+      CHECK_EQUAL(1, motorControl.common.startCount);
+      CHECK_EQUAL(0, motorControl.common.stopCount);
+      CHECK_EQUAL(0, motorControl.common.stoppedCount);
+      CHECK_EQUAL(0, motorControl.common.unknownCount);
+
+      // Send emergency Stop event.
+      motorControl.receive(etl::null_message_router(), Stop(true));
+
+      // Now in Idle state.
+
+      CHECK_EQUAL(StateId::IDLE, int(motorControl.get_state_id()));
+      CHECK_EQUAL(StateId::IDLE, int(motorControl.get_state().get_state_id()));
+
+      CHECK_EQUAL(false, motorControl.common.isLampOn);
+      CHECK_EQUAL(0, motorControl.common.setSpeedCount);
+      CHECK_EQUAL(0, motorControl.common.speed);
+      CHECK_EQUAL(1, motorControl.common.startCount);
+      CHECK_EQUAL(1, motorControl.common.stopCount);
+      CHECK_EQUAL(0, motorControl.common.stoppedCount);
+      CHECK_EQUAL(0, motorControl.common.unknownCount);
+    }
+  };
+}
diff --git a/test/test_message_router.cpp b/test/test_message_router.cpp
new file mode 100644
index 00000000..21d36330
--- /dev/null
+++ b/test/test_message_router.cpp
@@ -0,0 +1,325 @@
+/******************************************************************************
+The MIT License(MIT)
+
+Embedded Template Library.
+https://github.com/ETLCPP/etl
+http://www.etlcpp.com
+
+Copyright(c) 2017 jwellbelove
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files(the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and / or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions :
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+******************************************************************************/
+
+#include "UnitTest++.h"
+#include "ExtraCheckMacros.h"
+
+#include "message_router.h"
+
+//***************************************************************************
+// The set of messages.
+//***************************************************************************
+namespace
+{
+  enum
+  {
+    MESSAGE1,
+    MESSAGE2,
+    MESSAGE3,
+    MESSAGE4,
+    MESSAGE5
+  };
+
+  struct Message1 : public etl::message<MESSAGE1>
+  {
+
+  };
+
+  struct Message2 : public etl::message<MESSAGE2>
+  {
+
+  };
+
+  struct Message3 : public etl::message<MESSAGE3>
+  {
+
+  };
+
+  struct Message4 : public etl::message<MESSAGE4>
+  {
+
+  };
+
+  struct Message5 : public etl::message<MESSAGE5>
+  {
+
+  };
+
+  Message1 message1;
+  Message2 message2;
+  Message3 message3;
+  Message4 message4;
+  Message5 message5;
+
+  //***************************************************************************
+  // Router that handles messages 1, 2, 3, 4 and 5 and returns nothing.
+  //***************************************************************************
+  class Router1 : public etl::message_router<Router1, Message1, Message2, Message3, Message4, Message5>
+  {
+  public:
+
+    Router1()
+      : message1_count(0),
+        message2_count(0),
+        message3_count(0),
+        message4_count(0),
+        message_unknown_count(0),
+        callback_count(0)
+    {
+
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message1& msg)
+    {
+      ++message1_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message2& msg)
+    {
+      ++message2_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message3& msg)
+    {
+      ++message3_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message4& msg)
+    {
+      ++message4_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message5& msg)
+    {
+      ++callback_count;
+    }
+
+    void on_receive_unknown(etl::imessage_router& sender, const etl::imessage& msg)
+    {
+      ++message_unknown_count;
+    }
+
+    int message1_count;
+    int message2_count;
+    int message3_count;
+    int message4_count;
+    int message_unknown_count;
+    int callback_count;
+  };
+
+  //***************************************************************************
+  // Router that handles messages 1, 2, 4 and 5 and returns nothing.
+  //***************************************************************************
+  class Router2 : public etl::message_router<Router2, Message1, Message2, Message4, Message5>
+  {
+  public:
+
+    Router2()
+      : message1_count(0),
+        message2_count(0),
+        message4_count(0),
+        message_unknown_count(0),
+        callback_count(0)
+    {
+
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message1& msg)
+    {
+      ++message1_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message2& msg)
+    {
+      ++message2_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message4& msg)
+    {
+      ++message4_count;
+      etl::send_message(sender, message5);
+    }
+
+    void on_receive(etl::imessage_router& sender, const Message5& msg)
+    {
+      ++callback_count;
+    }
+
+    void on_receive_unknown(etl::imessage_router& sender, const etl::imessage& msg)
+    {
+      ++message_unknown_count;
+      etl::send_message(sender, message5);
+    }
+
+    int message1_count;
+    int message2_count;
+    int message4_count;
+    int message_unknown_count;
+    int callback_count;
+  };
+
+
+  etl::imessage_router* p_router;
+
+  SUITE(test_message_router)
+  {
+    //=========================================================================
+    TEST(message_router)
+    {
+      Router1 r1;
+      Router2 r2;
+
+      p_router = &r1;
+
+      p_router->receive(r2, message1);
+      CHECK_EQUAL(1, r1.message1_count);
+      CHECK_EQUAL(0, r1.message2_count);
+      CHECK_EQUAL(0, r1.message3_count);
+      CHECK_EQUAL(0, r1.message4_count);
+      CHECK_EQUAL(0, r1.message_unknown_count);
+      CHECK_EQUAL(1, r2.callback_count);
+
+      p_router->receive(r2, message2);
+      CHECK_EQUAL(1, r1.message1_count);
+      CHECK_EQUAL(1, r1.message2_count);
+      CHECK_EQUAL(0, r1.message3_count);
+      CHECK_EQUAL(0, r1.message4_count);
+      CHECK_EQUAL(0, r1.message_unknown_count);
+      CHECK_EQUAL(2, r2.callback_count);
+
+      p_router->receive(r2, message3);
+      CHECK_EQUAL(1, r1.message1_count);
+      CHECK_EQUAL(1, r1.message2_count);
+      CHECK_EQUAL(1, r1.message3_count);
+      CHECK_EQUAL(0, r1.message4_count);
+      CHECK_EQUAL(0, r1.message_unknown_count);
+      CHECK_EQUAL(3, r2.callback_count);
+
+      p_router->receive(r2, message4);
+      CHECK_EQUAL(1, r1.message1_count);
+      CHECK_EQUAL(1, r1.message2_count);
+      CHECK_EQUAL(1, r1.message3_count);
+      CHECK_EQUAL(1, r1.message4_count);
+      CHECK_EQUAL(0, r1.message_unknown_count);
+      CHECK_EQUAL(4, r2.callback_count);
+
+      p_router = &r2;
+
+      p_router->receive(r1, message1);
+      CHECK_EQUAL(1, r2.message1_count);
+      CHECK_EQUAL(0, r2.message2_count);
+      CHECK_EQUAL(0, r2.message4_count);
+      CHECK_EQUAL(0, r2.message_unknown_count);
+      CHECK_EQUAL(1, r1.callback_count);
+
+      p_router->receive(r1, message2);
+      CHECK_EQUAL(1, r2.message1_count);
+      CHECK_EQUAL(1, r2.message2_count);
+      CHECK_EQUAL(0, r2.message4_count);
+      CHECK_EQUAL(0, r2.message_unknown_count);
+      CHECK_EQUAL(2, r1.callback_count);
+
+      p_router->receive(r1, message3);
+      CHECK_EQUAL(1, r2.message1_count);
+      CHECK_EQUAL(1, r2.message2_count);
+      CHECK_EQUAL(0, r2.message4_count);
+      CHECK_EQUAL(1, r2.message_unknown_count);
+      CHECK_EQUAL(3, r1.callback_count);
+
+      p_router->receive(r1, message4);
+      CHECK_EQUAL(1, r2.message1_count);
+      CHECK_EQUAL(1, r2.message2_count);
+      CHECK_EQUAL(1, r2.message4_count);
+      CHECK_EQUAL(1, r2.message_unknown_count);
+      CHECK_EQUAL(4, r1.callback_count);
+    }
+
+    //=========================================================================
+    TEST(message_null_router)
+    {
+      Router2 router;
+      etl::null_message_router null_router;
+
+      // Send from the null router.
+      etl::send_message(router, message1);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(0, router.message2_count);
+      CHECK_EQUAL(0, router.message4_count);
+      CHECK_EQUAL(0, router.message_unknown_count);
+
+      etl::send_message(router, message2);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(0, router.message4_count);
+      CHECK_EQUAL(0, router.message_unknown_count);
+
+      etl::send_message(router, message3);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(0, router.message4_count);
+      CHECK_EQUAL(1, router.message_unknown_count);
+
+      etl::send_message(router, message4);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(1, router.message4_count);
+      CHECK_EQUAL(1, router.message_unknown_count);
+
+      // Send to the null router.
+      etl::send_message(null_router, message1);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(1, router.message4_count);
+      CHECK_EQUAL(1, router.message_unknown_count);
+
+      etl::send_message(null_router, message2);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(1, router.message4_count);
+      CHECK_EQUAL(1, router.message_unknown_count);
+
+      etl::send_message(null_router, message3);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(1, router.message4_count);
+      CHECK_EQUAL(1, router.message_unknown_count);
+
+      etl::send_message(null_router, message4);
+      CHECK_EQUAL(1, router.message1_count);
+      CHECK_EQUAL(1, router.message2_count);
+      CHECK_EQUAL(1, router.message4_count);
+      CHECK_EQUAL(1, router.message_unknown_count);
+    }
+  };
+}
diff --git a/test/vs2017/etl.vcxproj b/test/vs2017/etl.vcxproj
index 72989d79..736afc28 100644
--- a/test/vs2017/etl.vcxproj
+++ b/test/vs2017/etl.vcxproj
@@ -216,7 +216,6 @@
     <ClInclude Include="..\..\src\flat_map.h" />
     <ClInclude Include="..\..\src\map.h" />
     <ClInclude Include="..\..\src\memory.h" />
-    <ClInclude Include="..\..\src\mru_cache.h" />
     <ClInclude Include="..\..\src\multimap.h" />
     <ClInclude Include="..\..\src\multiset.h" />
     <ClInclude Include="..\..\src\multi_array.h" />
@@ -240,7 +239,6 @@
     <ClInclude Include="..\..\src\reference_flat_multimap.h" />
     <ClInclude Include="..\..\src\reference_flat_multiset.h" />
     <ClInclude Include="..\..\src\reference_flat_set.h" />
-    <ClInclude Include="..\..\src\rr_cache.h" />
     <ClInclude Include="..\..\src\set.h" />
     <ClInclude Include="..\..\src\smallest.h" />
     <ClInclude Include="..\..\src\stack.h" />
diff --git a/test/vs2017/etl.vcxproj.filters b/test/vs2017/etl.vcxproj.filters
index 815eb6b3..cd16db12 100644
--- a/test/vs2017/etl.vcxproj.filters
+++ b/test/vs2017/etl.vcxproj.filters
@@ -38,7 +38,7 @@
       <UniqueIdentifier>{7028012c-30c4-4993-b2d9-3b1521a610ae}</UniqueIdentifier>
     </Filter>
     <Filter Include="ETL\Frameworks">
-      <UniqueIdentifier>{5de50c3d-4679-4eb3-9b76-e43e1aad6a66}</UniqueIdentifier>
+      <UniqueIdentifier>{6be3bc76-e17c-4be0-8b0b-d1053e1a1761}</UniqueIdentifier>
     </Filter>
   </ItemGroup>
   <ItemGroup>
@@ -261,12 +261,6 @@
     <ClInclude Include="..\..\src\icache.h">
       <Filter>ETL\Containers</Filter>
     </ClInclude>
-    <ClInclude Include="..\..\src\mru_cache.h">
-      <Filter>ETL\Containers</Filter>
-    </ClInclude>
-    <ClInclude Include="..\..\src\rr_cache.h">
-      <Filter>ETL\Containers</Filter>
-    </ClInclude>
     <ClInclude Include="..\..\src\intrusive_links.h">
       <Filter>ETL\Containers</Filter>
     </ClInclude>
@@ -439,16 +433,16 @@
       <Filter>Header Files</Filter>
     </ClInclude>
     <ClInclude Include="..\..\src\fsm.h">
-      <Filter>ETL\Patterns</Filter>
+      <Filter>ETL\Frameworks</Filter>
     </ClInclude>
     <ClInclude Include="..\..\src\fsm_generator.h">
-      <Filter>ETL\Patterns</Filter>
+      <Filter>ETL\Frameworks</Filter>
     </ClInclude>
     <ClInclude Include="..\..\src\message_router.h">
-      <Filter>ETL\Patterns</Filter>
+      <Filter>ETL\Frameworks</Filter>
     </ClInclude>
     <ClInclude Include="..\..\src\message_router_generator.h">
-      <Filter>ETL\Patterns</Filter>
+      <Filter>ETL\Frameworks</Filter>
     </ClInclude>
   </ItemGroup>
   <ItemGroup>
@@ -788,10 +782,10 @@
       <Filter>Resource Files</Filter>
     </None>
     <None Include="..\..\src\CreateFSM.bat">
-      <Filter>ETL\Patterns</Filter>
+      <Filter>ETL\Frameworks</Filter>
     </None>
     <None Include="..\..\src\CreateMessageRouter.bat">
-      <Filter>ETL\Patterns</Filter>
+      <Filter>ETL\Frameworks</Filter>
     </None>
   </ItemGroup>
   <ItemGroup>