Path: csiph.com!weretis.net!feeder6.news.weretis.net!feeder.usenetexpress.com!feeder-in1.iad1.usenetexpress.com!border1.nntp.dca1.giganews.com!nntp.giganews.com!news.misty.com!news.iecc.com!.POSTED.gal.iecc.com!not-for-mail
From: Paul Rubin <no.email@nospam.invalid>
Newsgroups: comp.arch.embedded
Subject: Re: When exactly do you choose to use a RTOS (instead of a non-OS approach)?
Date: Sun, 07 Jan 2018 13:41:55 -0800
Organization: A noiseless patient Spider
Lines: 11
Message-ID: <87608dmjmk.fsf@nightsong.com>
References: <p0h1kt$tb7$1@dont-email.me> <p0jhvg$bb7$1@news2.open-news-network.org> <p13mob$dfn$2@dont-email.me> <ad8c675d-61e1-4e64-b511-af822e8ec1b8@googlegroups.com> <p1bg2u$5ke$2@dont-email.me> <p2igr5$j9j$1@dont-email.me> <p2j5mn$bev$2@dont-email.me> <p2jqj6$9jq$1@dont-email.me> <p2kotf$cu9$1@dont-email.me> <p2lve0$tuv$1@dont-email.me> <87vaghnndl.fsf@nightsong.com> <Dde4C.235794$Jg1.222201@fx33.am4>
Mime-Version: 1.0
Content-Type: text/plain
Injection-Info: gal.iecc.com; posting-host="gal.iecc.com:64.57.183.53"; logging-data="13505"; mail-complaints-to="abuse@iecc.com"
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux)
Funky-Path: eternal-september.org!reader02.eternal-september.org!.POSTED!not-for-mail
Funky-Injection-Info: reader02.eternal-september.org; posting-host="ae97e3878acaa56b84b352c4f0fedc83"; logging-data="19827"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1+3lISchQYNZp5q5CY92n76"
Cancel-Lock: sha1:J5gq88FWtwfrHz4/q96KCw69X14= sha1:tW33t4PgWseLcATk72r+YPHW3Xk=
Funky-Xref: reader02.eternal-september.org comp.arch.embedded:47117
Xref: csiph.com comp.arch.embedded:27549

Tom Gardner <spamjunk@blueyonder.co.uk> writes:
> But for many embedded systems, FSMs are (or IMNSHO ought to be!) a key
> component in structuring and expressing the design. Canonical examples
> are ATMs, car cruise control, comms/networking protocols etc.

I don't see a requirement for FSM's in any of those.  ATM's (I assume
you mean cash dispensers) just seem like they'd run normal business
code.  Cruise control sounds like a normal PID-like controller.  I've
written tons of comms code without FSM's.  On the other hand, maybe your
comm protocol involves checksums or error correcting codes.  Doing those
with FSMs would be straightforward in theory but ridiculous in practice.