.. include:: <mmlalias.txt>


Firmware: Not So Well Anymore
=============================

.. image:: fsm-bullshit.svg
   :scale: 80%

Problem: ISRs Not Simple
------------------------

* Three ISRs

  * Timer tick
  * Sensor burning
  * Operator button

* Initially (:doc:`here <../bare-metal-initial/index>`), each
  transition involved at most three GPIO operations
* Spinlock as bug fix (:doc:`here <../bare-metal-initial/index>`)

  * |longrightarrow| Possibly longer execution time but correct

* CAN notifications (:doc:`here <../bare-metal-can/index>`) hasn't
  improved the situation
  
  * Controller busy sending |longrightarrow| complicated queueing
    mechanism
  * Again interrupt driven