Re: Serial Port Emulation

From	David Brown <david.brown@hesbynett.no>
Newsgroups	comp.arch.embedded
Subject	Re: Serial Port Emulation
Date	2019-03-01 10:04 +0100
Organization	A noiseless patient Spider
Message-ID	<q5asj4$3nb$1@dont-email.me> (permalink)
References	(8 earlier) <q4sbal$sre$1@dont-email.me> <v3i37e57qvoghiqp27ki59vb0dj5g0hm16@4ax.com> <q57n0n$n4$1@dont-email.me> <q583bd$mas$1@dont-email.me> <276ad588-f75f-46e0-bd35-095030c00887@googlegroups.com>

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On 01/03/2019 00:07, gnuarm.deletethisbit@gmail.com wrote:
> On Thursday, February 28, 2019 at 1:41:36 AM UTC-6, David Brown wrote:
>> On 28/02/2019 05:15, Les Cargill wrote:
>>>
>>> Generally, I'll have a custom TCP server running on the Pi, which
>>> provides the option of encoding any twiddly parts about the device on
>>> the other end of the FTDI device, within the Pi.
>>
>> I don't know what kind of systems you work with, but to me a Pi is
>> convenient for testing and developing, but is out of the question for
>> most delivered systems.  The same goes for jumbled mixups with dynamic
>> DNS - fine for test setups, not for deployment.
> 
> It's nice to say you don't like using pis for delivered systems, but that's not useful to anyone else unless you explain why.  

Fair enough.

> 
> The rPi foundation even makes boards specifically for embedded systems and I believe they have some level of assurance these units will continue to be available. 

Normally when talking about a Pi without being specific, it is
reasonable to assume standard Pi boards.  These have no guaranteed
availability lifetime, no thoughts of MTBF or environmental limits, are
full of connectors without any locking or stability, are impractical for
any kind of solid mounting, and are not practically designed for
production, testing and integration with industrial systems that need to
be produced consistently, solidly, reliably, and cheaply.

These devices are made for the desktop - for education, experiments,
fun, prototypes, for cheap computers.  They are excellent for that.  But
not for later stages in most kinds of delivered embedded systems.  (Of
course there are some kinds of system where they are fine, but those are
in the minority.)  You buy you Pi boards one at a time, not in
deliveries of hundreds or thousands.

The embedded Pi cards /are/ more suited for production of finished
systems.  But they still suffer from the same disadvantage any embedded
Linux system has in comparison to using small microcontrollers - long
and complicated production programming, finer and more delicate
electronics, security, software auditing and control, software
licensing, timing jitter, boot times, large and complex updates,
unstable software, support, developer requirements, power requirements,
environmental limits.

Now, embedded Linux systems can give you enormous flexibility, and you
get a vast amount of software features and power for very little cost.
In many systems, this is what you want, and a Pi compute module (not a
normal Pi) may be a reasonable way to get that.  But in many more
systems, you don't need that - and the cost of having a much more
complex system is far too high.

> 
> 
>>> Almost everything has Ethernet now.
>>
>> Almost every microcontroller does /not/ have Ethernet.  Almost every
>> electronics board made does /not/ have Ethernet.
> 
> I think both statements are exaggerations.  Plenty of MCUs are Ethernet capable.  

I did a quick and unscientific test.  On Digikey, there are 78,510
microcontrollers.  4,498 have Ethernet.  (Yes, I know you get multiple
lines for essentially the same devices.)  I will admit that is a higher
proportion than I had expected.  But still, the great majority of
available types of microcontroller do not have Ethernet.  And while I
have no statistics here, I would expect the non-Ethernet
microcontrollers here to ship in several orders of magnitude higher
quantities than the the ones with Ethernet.  At what point can we say
that almost every microcontroller shipped does not have Ethernet?  99%
99.9%?  99.99%?

Certainly Ethernet is getting more common - there are more devices
available, and there are quality network stacks available freely.  There
is a much lower entry cost to using Ethernet now than there was 5 years
ago.  But still I stand by my statement that almost every board made
does not have Ethernet.

> If you want Ethernet it is easy to select a version with a network interface. 
> 

That is true, when you are at a certain size of microcontroller.  If you
are talking about a 32-bit device with 64 or more pins, 256K flash and
64K ram, running at 60+ MHz - yes, there is a high chance that you can
find a device in the same family that has Ethernet.  If you are using
8-bit or 16-bit microcontrollers, small or cheap devices (which may be
32-bit), low-power devices, high temperature devices, tiny package
devices - no, you probably won't find Ethernet alternatives without
changing family.

In my own designs, I am quite fond of Ethernet.  It gives a lot of
flexibility and convenience.  (I have a board plan which would have
Ethernet merely for development and debugging.)  But it is not for every
use.

Thread

Serial Port Emulation gnuarm.deletethisbit@gmail.com - 2019-02-17 02:08 -0800
  Re: Serial Port Emulation David Brown <david.brown@hesbynett.no> - 2019-02-17 13:42 +0100
    Re: Serial Port Emulation Chris <xxx.syseng.yyy@gfsys.co.uk> - 2019-02-17 15:49 +0000
  Re: Serial Port Emulation Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2019-02-17 18:54 +0200
    Re: Serial Port Emulation David Brown <david.brown@hesbynett.no> - 2019-02-17 21:16 +0100
      Re: Serial Port Emulation Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2019-02-18 10:38 +0200
        Re: Serial Port Emulation David Brown <david.brown@hesbynett.no> - 2019-02-18 10:49 +0100
          Re: Serial Port Emulation Richard Damon <Richard@Damon-Family.org> - 2019-02-18 07:25 -0500
            Re: Serial Port Emulation David Brown <david.brown@hesbynett.no> - 2019-02-18 14:31 +0100
              Re: Serial Port Emulation Andrew Smallshaw <andrews@sdf.org> - 2019-02-19 16:10 +0000
                Re: Serial Port Emulation gnuarm.deletethisbit@gmail.com - 2019-02-19 09:12 -0800
                Re: Serial Port Emulation upsidedown@downunder.com - 2019-02-19 19:58 +0200
                Re: Serial Port Emulation Grant Edwards <invalid@invalid.invalid> - 2019-02-19 18:22 +0000
                Re: Serial Port Emulation David Brown <david.brown@hesbynett.no> - 2019-02-19 22:50 +0100
                Re: Serial Port Emulation Grant Edwards <invalid@invalid.invalid> - 2019-02-19 22:23 +0000
                Re: Serial Port Emulation David Brown <david.brown@hesbynett.no> - 2019-02-20 08:53 +0100
                Re: Serial Port Emulation upsidedown@downunder.com - 2019-02-20 10:17 +0200
                Re: Serial Port Emulation Theo <theom+news@chiark.greenend.org.uk> - 2019-02-19 22:35 +0000
                Re: Serial Port Emulation upsidedown@downunder.com - 2019-02-20 01:36 +0200
                Re: Serial Port Emulation gnuarm.deletethisbit@gmail.com - 2019-02-19 19:40 -0800
                Re: Serial Port Emulation David Brown <david.brown@hesbynett.no> - 2019-02-20 09:00 +0100
                Re: Serial Port Emulation upsidedown@downunder.com - 2019-02-19 19:16 +0200
                Re: Serial Port Emulation Theo <theom+news@chiark.greenend.org.uk> - 2019-02-19 22:28 +0000
                Re: Serial Port Emulation David Brown <david.brown@hesbynett.no> - 2019-02-20 10:32 +0100
                Re: Serial Port Emulation Robert Wessel <robertwessel2@yahoo.com> - 2019-02-19 18:44 -0600
                Re: Serial Port Emulation Les Cargill <lcargill99@comcast.com> - 2019-02-23 14:48 -0600
                Re: Serial Port Emulation Robert Wessel <robertwessel2@yahoo.com> - 2019-02-23 16:34 -0600
                Re: Serial Port Emulation Les Cargill <lcargill99@comcast.com> - 2019-02-27 22:15 -0600
                Re: Serial Port Emulation David Brown <david.brown@hesbynett.no> - 2019-02-28 08:41 +0100
                Re: Serial Port Emulation gnuarm.deletethisbit@gmail.com - 2019-02-28 15:07 -0800
                Re: Serial Port Emulation David Brown <david.brown@hesbynett.no> - 2019-03-01 10:04 +0100
                Re: Serial Port Emulation gnuarm.deletethisbit@gmail.com - 2019-03-01 13:09 -0800
                Re: Serial Port Emulation Les Cargill <lcargill99@comcast.com> - 2019-03-04 17:58 -0600
                Re: Serial Port Emulation Paul Rubin <no.email@nospam.invalid> - 2019-03-01 02:25 -0800
                Re: Serial Port Emulation gnuarm.deletethisbit@gmail.com - 2019-03-01 13:16 -0800
                Re: Serial Port Emulation Paul Rubin <no.email@nospam.invalid> - 2019-03-01 16:45 -0800
                Re: Serial Port Emulation Les Cargill <lcargill99@comcast.com> - 2019-03-04 17:44 -0600
                Re: Serial Port Emulation Richard Damon <Richard@Damon-Family.org> - 2019-02-23 19:37 -0500
                Re: Serial Port Emulation Les Cargill <lcargill99@comcast.com> - 2019-02-27 22:17 -0600
          Re: Serial Port Emulation gnuarm.deletethisbit@gmail.com - 2019-02-18 06:28 -0800
          Re: Serial Port Emulation Stef <stef33d@yahooI-N-V-A-L-I-D.com.invalid> - 2019-02-18 22:33 +0100
  Re: Serial Port Emulation "A.P.Richelieu" <aprichelieu@gmail.com> - 2019-02-17 21:06 +0100
  Re: Serial Port Emulation raimond.dragomir@gmail.com - 2019-02-17 21:56 -0800
    Re: Serial Port Emulation gnuarm.deletethisbit@gmail.com - 2019-02-17 22:37 -0800
  Re: Serial Port Emulation "Mat Nieuwenhoven" <mnieuw@zap.a2000.nl> - 2019-02-18 12:34 +0100

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