Re: Do you use FSMs or HSMs?

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From	Don Y <blockedofcourse@foo.invalid>
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Subject	Re: Do you use FSMs or HSMs?
Date	Mon, 6 Feb 2017 18:11:58 -0700
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On 2/6/2017 5:52 PM, jim.brakefield@ieee.org wrote:
> On Monday, February 6, 2017 at 8:56:45 AM UTC-6, QL wrote:
>> Let me start with the full disclosure: I'm the author of the book
>> "Practical UML Statecharts in C/C++, 2nd Edition" and I run a company
>> called Quantum Leaps that makes open-source state machine software
>> frameworks and a free state machine modeling tool. The company website
>> is:
>>
>> http://www.state-machine.com
>>
>>
>> So, yes, I also strongly believe that hierarchical state machines (a.k.a.
>> UML statecharts) combined with event-driven programming are the best way
>> to go when it comes to developing real-time embedded software.
>>
>> From my two decades of experience, however, I see that the biggest
>> obstacle in adopting state machines is the required paradigm shift from
>> sequential programming based on blocking (like blocking on a semaphore or
>> a time delay in a traditional RTOS or a "superloop") and the event-driven
>> programming based on run-to-completion event processing without blocking
>> (like in a state machine).
>>
>> Anyway, if you are seriously interested in (hierarchical) state machines
>> for embedded real-time systems I would recommend to start with the key
>> concepts:
>>
>> http://www.state-machine.com/doc/concepts.html
>>
>>
>> You might also wish to try the free state machine modeling tool called
>> QM, which allows you to draw hierarchical state machine diagrams and
>> automatically generate production-quality C or C++ code from them:
>>
>> http://www.state-machine.com/qm
>>
>>
>> Miro Samek www.state-machine.com
>>
>> --------------------------------------- Posted through
>> http://www.EmbeddedRelated.com
>
> ]> Anyway, if you are seriously interested in (hierarchical) state machines
> ]> for embedded real-time systems I would recommend to start with the key ]>
> concepts:
>
> Not entirely enlightened on hierarchical state machines. Gather that the
> lower level state "inherits" from the higher level state. E.g., unless
> over-ridden, the lower level state defaults to the actions of the higher
> level state?
>
> Side issue: in communications many states use a timer to have a time-out
> action, and the methodology/diagrams accommodate this?

In my implementations, you can "call" (bad choice of terms but it is something
to which a programmer can easily relate!) a "state table" as if it had been
inserted into the current state table, "in line" (though it doesn't incur the
expected space penalty).

[likewise, common data entry FSMs "shared" in a larger UI FSM]

So, you take these common things and wrap them in a "pseudo state (table)"
and then reference (CALL) it from every state in which it should apply
(which might not be ALL states!)

E.g., I will embed power fail handling in such a pseudo table and add
it to every state that CAN support power fail handling (some might not
be designed to tolerate that exception).  Likewise, power *recovery*
in the same pseudo table (each maintaining a separate FSM orthogonal
to the FSM in question and interacting with it in the applicable
"transition routines")

Thread

Do you use FSMs or HSMs? pozz <pozzugno@gmail.com> - 2017-02-06 10:43 +0100
  Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 03:20 -0700
  Re: Do you use FSMs or HSMs? Dave Nadler <drn@nadler.com> - 2017-02-06 06:38 -0800
  Re: Do you use FSMs or HSMs? "QL" <80499@EmbeddedRelated> - 2017-02-06 08:56 -0600
    Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 12:13 -0700
    Re: Do you use FSMs or HSMs? jim.brakefield@ieee.org - 2017-02-06 16:52 -0800
      Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 18:11 -0700
      Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-06 23:32 -0600
    Re: Do you use FSMs or HSMs? pozz <pozzugno@gmail.com> - 2017-02-07 10:39 +0100
  Re: Do you use FSMs or HSMs? John Speth <johnspeth@yahoo.com> - 2017-02-06 09:17 -0800
    Re: Do you use FSMs or HSMs? Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-06 18:03 +0000
      Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 11:56 -0700
        Re: Do you use FSMs or HSMs? Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-06 20:34 +0000
          Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 14:19 -0700
            Re: Do you use FSMs or HSMs? Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-06 22:12 +0000
              Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 15:29 -0700
              Re: Do you use FSMs or HSMs? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-08 12:15 -0500
                Re: Do you use FSMs or HSMs? Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-08 23:52 +0000
                Re: Do you use FSMs or HSMs? Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-08 19:59 -0500
              Re: Do you use FSMs or HSMs? Steve Watt <steve.removethis@Watt.COM> - 2017-02-17 00:30 +0000
                Re: Do you use FSMs or HSMs? Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-17 00:44 +0000
            Re: Do you use FSMs or HSMs? Clifford Heath <no.spam@please.net> - 2017-02-07 10:12 +1100
              Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-06 23:36 -0600
                Re: Do you use FSMs or HSMs? George Neuner <gneuner2@comcast.net> - 2017-02-07 03:15 -0500
                Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-10 17:41 -0600
                Re: Do you use FSMs or HSMs? Clifford Heath <no.spam@please.net> - 2017-02-07 19:56 +1100
                Re: Do you use FSMs or HSMs? Paul Rubin <no.email@nospam.invalid> - 2017-02-07 01:30 -0800
                Re: Do you use FSMs or HSMs? Clifford Heath <no.spam@please.net> - 2017-02-07 20:42 +1100
                Re: Do you use FSMs or HSMs? Paul Rubin <no.email@nospam.invalid> - 2017-02-07 02:46 -0800
                Re: Do you use FSMs or HSMs? Clifford Heath <no.spam@please.net> - 2017-02-08 00:27 +1100
  Re: Do you use FSMs or HSMs? Paul Rubin <no.email@nospam.invalid> - 2017-02-06 18:35 -0800
    Re: Do you use FSMs or HSMs? Don Y <blockedofcourse@foo.invalid> - 2017-02-06 21:50 -0700
    Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-06 23:39 -0600
      Re: Do you use FSMs or HSMs? Paul Rubin <no.email@nospam.invalid> - 2017-02-06 23:20 -0800
        Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-10 17:47 -0600
          Re: Do you use FSMs or HSMs? Paul Rubin <no.email@nospam.invalid> - 2017-02-10 16:11 -0800
            Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-11 15:43 -0600
  Re: Do you use FSMs or HSMs? Les Cargill <lcargill99@comcast.com> - 2017-02-06 23:24 -0600

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