SBC in a BOX - Page 1
Forum section: electronics / projects

author: gnuarm
author_rank: Super Contributor
timestamp: January 17, 2023, 04:35:46 pm
content: I'm looking for a boxed MCU board with an RS-232 port on it. It would probably be better to have two connectors, rather than a Y cable, so make that two RS-232 ports.I'm having the hardest time finding something this simple. I can find what look like ideal candidates that are actually USB or Ethernet serial port units. They come in nice, solid looking metal boxes, good prices, etc. But so far, none of them are programmable.Anyone know of such off the shelf units? I'm not real particular about the processor inside. Currently this is being done on an Arduino nano, so the requirements are not much. The ports are 9,600 bps.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 17, 2023, 05:17:08 pm
content: SBC running what ? windows, linux ?? you have many models / brands etc ... as you wroteyou have powerful arduinos with many serial ports, but sometime its only tx and rx, do you need the other pins ?? cts rts etc ...Arm based sbc ...Examplehttp://www.a2s.pl/en/rs-232-x4-and-more,single-board-computer--t--2241-1932.htmlthey have rs232 headers and you connect the cable on them ??do you want a real db9 connector instead ?3d print you own case ?? you have nano itx boards, pc104 compatible sbcAAEONAxiomtekCommell you have many models with tons of rs232, different board sizeshttps://circuitcellar.com/research-design-hub/tech-trends/rugged-sbcs-bulk-up-for-harsh-environment-work/But some of the prices will make you jump ..you have very good usb to rs232 adapters with all the pinouts and buffer ic's in them, FTDI based, never had any problem with them

author: gnuarm
author_rank: Super Contributor
timestamp: January 17, 2023, 08:23:33 pm
content: Quote from: coromonadalix on January 17, 2023, 05:17:08 pmRunning the application. Why would this have need for an OS???QuoteNot looking for a board. There is no shortage of boards available, including the one this was prototyped with, an Arduino nano.Looking for a complete unit in a box, add programming and run.This is a similar unit to what I am thinking. But it's a fixed function product with no option of programming... although I've written them to ask.https://www.brainboxes.com/product/ethernet-to-serial/db9/es-257

author: bidrohini
author_rank: Regular Contributor
timestamp: January 18, 2023, 06:41:32 am
content: I am afraid that it won't be possible to find exactly what you want. This RS-232 hat+Raspberry Pi 4 can be an option.https://www.waveshare.com/2-ch-rs232-hat.htmhttps://www.theengineeringprojects.com/2022/02/introduction-to-raspberry-pi.html

author: westfw
author_rank: Super Contributor
timestamp: January 18, 2023, 06:51:59 am
content: I think perhaps the regulatory requirements for selling a box (ie a finished "product") vs just a board (a "component" that wouldn't need safety or emissions testing) may be insurmountable...I did design what seems like a near-perfect board for your application, though:https://hackaday.io/project/19761-serialmunger(It'sprobably obsolete. Nowadays I'd use one of the new AVR-Dx chips.)

author: gnuarm
author_rank: Super Contributor
timestamp: January 18, 2023, 07:05:09 am
content: Quote from: westfw on January 18, 2023, 06:51:59 amSo you think these are impossible???https://www.brainboxes.com/product/usb-to-serial/usb/us-257https://www.brainboxes.com/product/ethernet-to-serial/db9/es-257

author: gnuarm
author_rank: Super Contributor
timestamp: January 18, 2023, 07:07:44 am
content: Quote from: bidrohini on January 18, 2023, 06:41:32 amWhat possible reason would there be for it to be impossible to find an MCU in a box with two serial ports???QuoteThe rPi is one of the last units I would consider for this. It has no RS-232 on board and has an OS, which is such far overkill, that it gets in the way. It also sucks down far too much power for this simple application.

author: westfw
author_rank: Super Contributor
timestamp: January 18, 2023, 09:15:58 am
content: QuoteAre they programmable?There's no problem creating a product. I'm claiming that there's a problem creating a "platform" for people to use in creating their own product, which is seemed like OP was asking for.There are things like this:https://www.argentdata.com/catalog/product_info.php?products_id=58

author: gnuarm
author_rank: Super Contributor
timestamp: January 18, 2023, 01:01:25 pm
content: Quote from: westfw on January 18, 2023, 09:15:58 amI'm asking what the problem would be.QuoteThat's interesting, but has no processor board. Thanks.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 18, 2023, 02:19:24 pm
content: Maybe a PLC?

author: TheMG
author_rank: Frequent Contributor
timestamp: January 18, 2023, 02:35:57 pm
content: Perle IOLAN serial-to-ethernet converters might be something to look into.Rather expensive, but they do have the ability to load custom plugins and have a SDK available.https://www.perle.com/products/iolan-stg-terminal-server.shtml

author: Doctorandus_P
author_rank: Super Contributor
timestamp: January 18, 2023, 02:36:18 pm
content: The picture below is what is usually regarded as a SBC with serial in a box. I don't understand why you're rambling on about an arduino, I hate those things.

author: gnuarm
author_rank: Super Contributor
timestamp: January 19, 2023, 08:56:23 am
content: Quote from: NiHaoMike on January 18, 2023, 02:19:24 pmThey tend to be overkill. I've yet to find one that isn't running Windows or Linux. Not so cheap either.

author: gnuarm
author_rank: Super Contributor
timestamp: January 19, 2023, 08:57:55 am
content: Quote from: TheMG on January 18, 2023, 02:35:57 pmThey don't offer prices on their site. I guess if you have to ask, you can't afford it.Actually, I talked to them about their products for a different use. I need to review those emails.

author: gnuarm
author_rank: Super Contributor
timestamp: January 19, 2023, 09:00:50 am
content: Quote from: Doctorandus_P on January 18, 2023, 02:36:18 pmYes, I agree, you don't understand.How much are these boxes. Anything under $500? THAT'S why an Arduino type product is more appropriate. The task is so simple, the Arduino is almost overkill.

author: robert.rozee
author_rank: Frequent Contributor
timestamp: January 19, 2023, 10:30:36 am
content: would a raspberry pi PICO fill your needs? it has two onboard 3v3 level serial ports, so you would need level converters if you needed RS232 levels. the PICO can run a python interpreter, or MMbasic provides a complete onboard development environment via a CDC serial console interface running over USB. this leaves both serial ports free for your application program to use:https://geoffg.net/picomite.htmlany old box would house it, just stick the PICO board down with a piece of double-sided foam tape. PICOs are readily available for just a few dollars each.cheers,rob :-)

author: gnuarm
author_rank: Super Contributor
timestamp: January 19, 2023, 06:50:47 pm
content: Quote from: robert.rozee on January 19, 2023, 10:30:36 amThe rPi nano is like the Arduino nano in all regards, except it uses an OS. I suppose, in theory, the processor can be programmed like a basic MCU, but there's no advantage to that over the Arduino.The design only needs one serial port, because the receive is from one unit and the transmit is to the other unit. If the splitting cabling is inside the box, fine. That's what is being done. But the rPi nano doesn't come in a box, except maybe a blister pack or something. The rPi nano still requires a second board to level shift the RS-232 signals, so exactly like the Arduino nano.Looking for a box level product, not a board level product.

author: tooki
author_rank: Super Contributor
timestamp: January 19, 2023, 07:28:57 pm
content: Quote from: gnuarm on January 17, 2023, 08:23:33 pmI think the issue is your use of the term “SBC” in the thread title. Generally speaking, MCU boards and SBCs are considered different things, with SBC meaning a beefier thing running a “real” OS like Linux or Windows. The Raspberry Pi is the archetypal SBC, while Arduino, ESP32, STM32 Nucleo, RPi Pico, etc. are archetypal MCU boards (regardless of whether an RTOS is used or not).

author: tooki
author_rank: Super Contributor
timestamp: January 19, 2023, 07:33:07 pm
content: Quote from: gnuarm on January 18, 2023, 07:07:44 amBecause there’s practically no use for such a thing? An MCU is useless on its own, it needs peripherals and code to make it do anything. Closed boxes with MCUs do exist, but with the MCU preprogrammed and with ports selected for a specific purpose. (In other words, as a finished product that happens to use an MCU internally.)Maybe you should tell us what your actual application is?

author: gnuarm
author_rank: Super Contributor
timestamp: January 19, 2023, 08:08:59 pm
content: Quote from: tooki on January 19, 2023, 07:28:57 pmOk, I hope this has been cleared up by now. Thanks

author: gnuarm
author_rank: Super Contributor
timestamp: January 19, 2023, 08:12:53 pm
content: Quote from: tooki on January 19, 2023, 07:33:07 pmI'm not following your point. No computer is useful without a program to run. That's true of any computer, of any size of any configuration.The application is to accept data from one serial port, process that data in very, very simple ways, then output data on the other serial port. The average data rate is much lower than the bit rate of the serial ports, so very little buffering is required. A small program - maybe 100 to 200 lines (not counting serial port and start up code).

author: tooki
author_rank: Super Contributor
timestamp: January 19, 2023, 09:18:56 pm
content: Quote from: gnuarm on January 19, 2023, 08:12:53 pmDon’t be a pedant. You know exactly what I meant.A computer (by which I mean a PC, SBC, etc, but NOT a MCU) is functional out of the box: at most, attach a storage device with the OS on it, and it can bring itself up. You can add software to itusing itself, or write the software on it.In contrast, an MCU needs to have firmware flashed onto it. (Most don’t even come with a bootloader by default.)Quote from: gnuarm on January 19, 2023, 08:12:53 pmSo what’s wrong with buying an MCU board, some RS-232 level shifters, and a box to put it in? Why does it have to be a product bought preassembled? It’s a specialized application, presumably, such that nobody sells such a thing already?

author: gnuarm
author_rank: Super Contributor
timestamp: January 19, 2023, 10:28:25 pm
content: Quote from: tooki on January 19, 2023, 09:18:56 pmYes, and I'm making the point that your point is not valid. That's not pedantic.QuoteFunctional for what? It's not really useful until you install the application software. The OS is essentially a part of the computer. Without additional software it is no more useful than the MCU board, just more complicated. You can't write software for it until you install the software to write and compile and run software. Maybe that came with the PC, but that's not a required part of a PC by any means and the vast majority don't include such software.QuoteSounds a lot like a PC, where you have to set up all manner of things and install a great deal of software before it is useful.But none of that is relevant to the topic. No OS is required for this task.QuoteThat's what we have. I'm looking for something else. The box is not application specific. In fact, most computers are application agnostic, other than the peripherals required.Thanks for your comments.

author: SiliconWizard
author_rank: Super Contributor
timestamp: January 19, 2023, 10:39:53 pm
content: Quote from: gnuarm on January 17, 2023, 08:23:33 pmI think people got "confused" due to the "SBC" in your title. SBCs are usually those boards with a rather powerful SoC (at least compared to a MCU), USB, Ethernet, etc. And those usually can't run without an OS - you can program them baremetal, as I mentioned in another thread, but that's usually undocumented and not the way to go unless you absolutely need this kind of CPU power without any OS in between.So, that's just this SBC term that got you quite a few, probably off-topic (for you) answers.As I got it, you'd simply like some MCU dev board, nothing too fancy either, but ready to use inside a nice enclosure.Any reason why you are not just looking for a dev board that matches your needs, a separate enclosure, and then integrate it yourself, so you'd get exacty what you need? Will you need to get this in quantities?

author: tooki
author_rank: Super Contributor
timestamp: January 19, 2023, 11:16:16 pm
content: Quote from: gnuarm on January 19, 2023, 10:28:25 pmOf course you’re being pedantic. You know damned well the difference between application software on a PC and firmware on an MCU. (And if you legitimatelydon’tknow the difference, then you need to take a step back and listen instead of lecturing.) You haven’t invalidated my point, because you aren’t actually hearing what my point is (or rather, are pretending to not hear it).Quote from: gnuarm on January 19, 2023, 10:28:25 pmI saidfunctional, notuseful.The point is this: an MCU requires another computer (or standalone programmer) to get it running. From the factory, it is completely brain-dead.A PC/SBC, on the other hand, ships in a state — both hardware and firmware — where (assuming it doesn’t have an OS installed already) it can easily have its OS installedwithoutthe help of another computer. And with the OS installed, user software can be installed, again without the help of another computer.Quote from: gnuarm on January 19, 2023, 10:28:25 pmIt’s nothing like a PC, and you know this.Quote from: gnuarm on January 19, 2023, 10:28:25 pmAnd yet you started this very adversarial tangent based on a pedantic retort to a statement that you understood just fine.I said it just doesn’t make sense to sell closed-box MCU devices, because MCUs can’t do anything without peripherals and code. (A PCcandosomethingout of the box: interface with some sort of user interface and storage or network, such that the user can, without needing another computer, load software on it to make it useful. It isn’t “brain dead” out of the box.)Quote from: gnuarm on January 19, 2023, 10:28:25 pmYep.Quote from: gnuarm on January 19, 2023, 10:28:25 pmAgain: WHY does it have to be a product bought preassembled?Quote from: gnuarm on January 19, 2023, 10:28:25 pmWell yours is. An RS-232 to RS-232 data processor for whatever mysterious secret application you’ll be using it for is, in fact, very specific.You seem to expect there to be ageneralMCU-in-a-box product that contains exactly the peripherals your specific application requires. Such things do exist, but then they’re not general, and so we don’t call them MCUs in boxes, we call them by the name of whatever function the thing does.Quote from: gnuarm on January 19, 2023, 10:28:25 pmPeripherals and code. But they make all the difference.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: January 20, 2023, 01:45:59 am
content: Quote from: gnuarm on January 19, 2023, 09:00:50 amThey start at around EUR300.

author: robert.rozee
author_rank: Frequent Contributor
timestamp: January 20, 2023, 02:44:34 am
content: Quote from: gnuarm on January 19, 2023, 08:12:53 pmi'm guessing you want is to no longer do assembly in-house?while you are unlikely to find anything pre-made that fits all your requirements, there are any number of small businesses (or individuals) out there who could throw together a design that fulfills your needs, and is a fraction of the cost (per unit) of the many hundreds of dollars for what others have been suggesting. they may also be able to complete assembly to the closed-box stage for you.a few questions:1. what is the box to be powered from? an existing 5v/9v/12v source? please specify lower and upper limits. are you happy for there to just be a barrel jack on the side for power in?2. are you OK with 2x DB9 plugs or sockets for the serial ports?3. do you prefer the box contains an arduino NANO, or a raspberry pi PICO? in some regards the PICO is a little easier to work with, but on the other hand you may wish to retain your existing code and so go for a NANO. PICOs have one big advantage today in that they are readily obtainable.4. the box would additionally have a hole in the side for uploading firmware, as well as possibly a push button for selecting upgrade mode.whoever designs this for you will lay out a PCB that is shaped to fit an existing enclosure with removable ends. such as this one for example:https://nz.element14.com/hammond/1593lalgy/enclosure-instrument-abs-grey/dp/3276681there will be two DB9 at one end, and power in and USB cutout at the other. the NANO or PICO will plug into the PCB. it is highly likely that the PCB manufacturer will be able to also load components. see, for example:https://jlcpcb.com/smt-assemblyi believe JLCPCB can also patch-mount a PICO if you go down that path.is this getting close to what you are after?cheers,rob :-)

author: gnuarm
author_rank: Super Contributor
timestamp: January 20, 2023, 04:44:10 am
content: Quote from: robert.rozee on January 20, 2023, 02:44:34 amI don't get this. The requirements are pretty minimal. That's what has surprised me, that there are no box level products at the low end. Literally TONS of board level products (well, if you don't include the RS-232 drivers). It's like the market is all about playing with MCUs rather than using them in useful products.Quote120V as provided in the US. This can be a wall wart.QuoteThe serial ports should be DB-9 connectors.QuoteIt doesn't need to be an Arduino, but any processor typically run without an OS. I suppose an rPi could be used, but they typically are used with an OS and that's an unneeded encumbrance.QuoteThis is such a simple application that the OS provides virtually nothing to the task. The only I/O is the RS-232 interface which only requires simple UART support. Not really a justification to drag an OS into the game.QuoteThis is currently being done on the Arduino using the serial port (not ports). The one port is split between input and output of the serial stream.QuoteThis thread is about finding a box level product, not designing and constructing boards.

author: tooki
author_rank: Super Contributor
timestamp: January 20, 2023, 07:52:59 am
content: MCU boards are typically called “dev boards” (development boards) precisely because they’re used during development; the typical next step is to design your own board. Dev boards aren’t about “playing”, but development. What they aren’t intended for is use in a final product.

author: gnuarm
author_rank: Super Contributor
timestamp: January 20, 2023, 08:57:15 am
content: Quote from: tooki on January 20, 2023, 07:52:59 amThank you for your advice.

author: westfw
author_rank: Super Contributor
timestamp: January 20, 2023, 09:25:23 am
content: QuoteGood questions!But let's cut to the chase:How many are you going to buy, on what sort of schedule?You might be able to negotiate with Brainbox to get programming info and wholesale prices for one of their boxes, which is pretty close to what need, apparently. (aside from have a whole extra ethernet an enough guts to support it.)I've done that - found a box whose guts would run "our" software, and had "my people" negotiate with the manufacturer to let us resell the box with our own software (re-branding the box, giving us enough data to program it, etc.) It was a very expensive product, by today's standards... (the cisco STS-10, if you're curious. a 10port Ethernet to RS232 "terminal server." I saw the original CMC box at a trade show, asked whether they'd sell us the bare box, set the ball in motion, as it were. It was an "OK" product, I guess. Filled a niche that we weren't willing to spend our own HW design resources to build.)

author: gnuarm
author_rank: Super Contributor
timestamp: January 20, 2023, 11:02:15 am
content: Quote from: westfw on January 20, 2023, 09:25:23 amI've sent Brainbox a couple of emails. We'll see if they respond. So far, not even an acknowledgement I've reached a human.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 20, 2023, 01:23:12 pm
content: Are the protocols used somewhat standard? Maybe you can find an anybus converter...Anyhow, what I know is available are embedded pc's with intel atom class pc's for less than a few hundred that have two real serial ports (eg: IBASE).You can run a headless linux on those launching your python processing or whatever. Optional IO header for your button or status light. They are robust and last for years.

author: gnuarm
author_rank: Super Contributor
timestamp: January 21, 2023, 08:16:26 pm
content: Quote from: Jeroen3 on January 20, 2023, 01:23:12 pmI didn't find anything useful searching under Anybus, assuming that was a product name. They make much more complex systems than I am looking for. The only "converter" I was able to find is a module to allow the internal signals to be shifted to RS232 levels.I did find these devices.http://www.artila.com/en/p_matrix.html#Matrix-504But they are not so cheap and still run Linux. But it shows that looking for a self contained unit that is not a full PC is not unreasonable.

author: gnuarm
author_rank: Super Contributor
timestamp: March 27, 2023, 06:32:05 pm
content: I've not been able to find a box with appropriate "guts" to do this job. But I have found appropriate "guts" without the box. I was getting ready to go with a low end PC in a box (~$300) and found a company that makes a dual RS-232 interface for the Arduino Mega. It seems like a good fit.Now I still need a way to get an affordable box built.