On Friday, March 1, 2019 at 3:04:39 AM UTC-6, David Brown wrote:
> 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.
That makes no sense to me. If they make board intended for commercial use, then why not talk about those?
> These have no guaranteed availability lifetime,
Sure, if you limit your discussion to boards that are not intended for commercial use... they aren't likely going to be a perfect match to a commercial application.
> no thoughts of MTBF or environmental limits, are
> full of connectors without any locking or stability,
How is that different from most embedded, Linux CPU boards? Beagle Bone is pretty much the same in this regard.
> are impractical for any kind of solid mounting,
That's not in evidence. All but the first rPi have mounting holes.
> and are not practically designed for
> production, testing and integration with industrial systems that need to
> be produced consistently, solidly, reliably, and cheaply.
Absolutely no evidence to support any of this... especially the "cheaply" part!
> 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.
Simply not true. I can buy 4600 of the rPi 3A+ off the shelf.
> 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,
I don't get why you think this is such a poor device for embedded work. None of the above is valid.
> finer and more delicate
> electronics,
??? I don't think you work with electronics much.
> security, software auditing and control, software
> licensing, timing jitter, boot times, large and complex updates,
> unstable software, support, developer requirements, power requirements,
> environmental limits.
You aren't talking about the rPi. You are talking about Linux computers in general. Yes, if you don't want a Linux computer, then a Linux computer is a bad choice.
> 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.
The only real difference between the rPi 3B+ or rPi 3A+ and the compute unit is that the compute unit needs more stuff on the mother board.
> >>> 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%?
That is not a useful issue. The issue is whether you can get Ethernet or not. The answer is you can use Ethernet in pretty much any app you wish because you can buy a chip or board with networking across the range of sizes of MCUs/CPUs other than the smallest that get used in toasters and microwaves.
> 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.
You can stand anywhere you want. You just contradicted yourself.
> > 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.
Ok, so what is your point?
> 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.
No shoe fits every foot. Of course.
Rick C.