.. include:: <mmlalias.txt>


Firmware: Dedicated Thread For CAN Transmission
===============================================

.. topic:: Teacher's note

   * Talk about priorities (we'll be creating a medium priority
     thread)
   * After transformation: shorten the critical section by relieving
     it out message queue operation

.. image:: fsm-can-thread.svg
   :scale: 80%

Plan
----

**"Physical" Separation**

* In ``main()``, create a message queue
* In ``main()`` create a medium priority thread, and pass it

  * The queue's read end
  * A CAN controller from :doc:`../can-jf0815-blocking/index`

* Pass the write end to the FSM
* Remove CAN ISR from FSM
* In ``FSM::_state_change()``, write into the message queue

**Decouple FSM From CAN**

* All we want is *state change notifications*
* From FSM point of view, CAN is irrelevant
* |longrightarrow| Message queue carries plain FSM state
* Frame created in CAN-thread

``main()``: CAN Thread
----------------------

.. literalinclude:: code/main.cpp
   :caption: :download:`code/main.cpp`
   :language: c++

FSM: Send State On Message Queue
--------------------------------

.. literalinclude:: code/fsm.h
   :caption: :download:`code/fsm.h`
   :language: c++

.. literalinclude:: code/fsm.cpp
   :caption: :download:`code/fsm.cpp`
   :language: c++