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From: Les Cargill <lcargill99@comcast.com>
Newsgroups: comp.arch.embedded
Subject: Re: Do you use FSMs or HSMs?
Date: Mon, 6 Feb 2017 23:24:14 -0600
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pozz wrote:
> I often encounter many problems when I have to implement a "behaviour"
> in a microcontrollor. For example, I have some analog/digital inputs and
> some user commands. Based on that, the logic should set some outputs
> (digital or analog).
>
> Most of the time you (the developer) must understand what is the good
> behaviour of the machine, because noone is able to describe it in a good
> way. I usually heard the sentence: when the user presses the ON button,
> you switch on the engine.
> After some short implementation, you understand that the engine should
> be on only if the interlock input is closed.
> And so on...
>
> I think the best method to describe a machine behaviour is a
> state-machine, mainly a hierarchically state-machine (HSM). Do you agree?
>

It all depends. This being said, I do like state machines, mainly 
because they lend well to comprehensive unit/regression test suites
and have some advantage in coverage measurement.

Hierarchical may or may not help that much.

> My post here is to understand if you really use HSMs to describe the
> beahviour of the system you are coding and how do you implement them in
> C or C++ (or whatever).
>

I have implemented them in multiple languages and programing paradigms.

-- 
Les Cargill