Boxed MCU with RS-232 Port

Yeah, that's just what engineers do. They throw some stuff together and test it, over and over, rather than actually understanding the requirements.

I'm trying to get you to understand the issues, but you just aren't getting it. I don't know how a cable I have no info on is wired. But if pin 3 on the CPU connector goes to pin 2 on both of the cable connectors, then it's not likely to work properly is it? Two drivers on the same pin sound like a bad idea to me.

Does it have RS-232 driver chips?

I would hope so. Do any of the boards you are talking about have USB host ports? Typically the small CPU boards use a USB to serial port chip to support bootloading, with no drivers on the CPU to host USB.

I think that is something we can worry about later. So far, I'm not sure you can produce any boxes.

When you get the details worked out, and wish to discuss a price, let me know through email.

Thanks

Again there is a 3 step process going on: 1) note that a product of this sort exists, without remembering too much detail about it. 2) find the product description page again, and this time study it carefully including the pin diagrams, to develop a theory of whether it does the right thing and which pins to connect or disconnect. 3) actually buy the cable and test the theory.

Right now we are at step 1. I think it is best to avoid the whole thing though. The approach of splitting the pins out from a single port is too kludgy, if it is at all practical to use two ports.

No it does not. That is why I linked those level shifter cards.

The ESP32-S2 has it. Here are the API docs:

The CDC (communication device class) software is here:

It looks like a potential pain in the neck to use. I currently have an Adafruit Feather board with that chip so maybe I will try it.

The chip also supports wifi and bluetooth, fwiw. The software stacks for both of those are way more complicated than USB.

OK.

"Terminal Equipment" (TE) vs "Communications Equipment" (CE).

DTE is the computer (terminal), DCE is the modem. To adhere to the RS-232 conventions, your external device has to be "communications equipment".

Don explained the cables and how the signaling works. DTE transmits on TxD, and receives on RxD. DCE does the reverse. Which physical pins these are on depends on the form factor: DB9 or DB25.

RS-232 pinout diagrams are very easy to find. Try Google.

You are confused. I don't need any information about RS-232. Everything you are talking about is irrelevant. Virtually NO ONE uses RS-232 to connect DCE to DTE. They simply are tying together two devices that wish to use asynch serial at RS-232 voltage levels.

But neither you nor Don seem to understand that. I was trying to lead Don to this conclusion by asking pointed questions, but that failed. You, however, seem to have the same problem Don does.

I often have this problem with people who don't actually understand how RS-232 is used. There are people who view the world through data sheets and specification standards. Then there's the real world, where you have to toss out some of that, and ask questions like, "Which pin is output and which pin is input?" If the person you are talking to gives you anything other than a pin number, you are talking to the wrong person.

Engineers design stuff. Technicians figure out how to make it work.

Many years ago I often had to connect up gear with RS232 interfaces, and it was a pain, as there was often no manual for the gear or the manual was badly written and the author used the RS232 "standard" terms in a cavalier way.

So I used an RS232 breakout box to try and identify RXD and TXD, and what the various pins did, and what had to be strapped to what to get either end to speak! Oh happy days - NOT!

Good luck with the project.

Hard to believe the long fossilized RS-232 horse can get all that beating again... Next thing let's beat the baud rate detection? :D

Fortunately, this effort only uses TX and GND on one port and RX and GND on the other port. I don't care what the TX and RX pins are called, one is input, the other output and we just need to connect the input to the device that is sending the data and connect the output to the device that is receiving data. All this has already been worked out and a prototype was built. Unfortunately there is some problem that results in a hung unit from time to time. That developer doesn't have the time to mess with it, so we are looking elsewhere. But the pin assignments are not a problem, just people's perspective on the issue.

And there is the problem. The RS-232 standard defines the interface between data terminal equipment and data communication equipment, at the data communication equipment interface. It says nothing about anything else. However, people use these voltages and so these level shifting devices, often along with the same type of connectors for many *other* applications. At that point, the RS-232 standard does not apply in a consistent way. So people are free to pick and choose the parts they want, and the parts they don't want.

The RS-232 moniker is often used, when even the voltage levels are not the same. At that point, there is nothing RS-232 about it. People are just using the term as a synonym for an async serial port.

The comedy here, is that both of you think I was saying anything about RS-232 being useful here, as other than a voltage level standard. I expect that of you. I don't know George so well.

I was playing the game, where questions are asked, until the other person sees the absurdity of what they were saying. You still haven't figured that out.

You seem to have gone off the weird end. I wish GG had a kill file feature. At least you managed to post without overflowing everyone's input buffers. You seem to have a penchant for using 100 words, when 20 will do.

Thanks for keeping this one brief.

Wow! He's gone from making overly verbose posts with far more description than needed, to making replies to himself, neither of which are needed.

Don, why are you here? Why are you posting in this thread? You have gone completely off topic.

Thanks,

Rick, why are /you/ here? You have been on Usenet for decades, but still seem to struggle with the basics.

A group like this is a discussion group. It is not your personal support channel. You do not have any rights to the group, or any rights to the thread. If Don wants to post here, he can post here. If he wants to ramble or rant (and he does like doing that - he has a lot of experience and likes to share), that's his right and his choice. Ignore his posts if you don't like them.

You have spent this thread bullying and insulting people, pushing them into doing your work for free. When it looks like some here might be possible paid suppliers, you undermine and patronise them.

When you come looking for help and advice, it's fair enough to disagree

- but we can do without the sarcasm and belittlement of your responses.

And if you want to killfile me for writing some hard truths, go ahead. But first you'll have to figure out how to use Usenet instead of blaming Google Groups for your own problems.

You are off topic in this thread. Why not start your own thread, rather than polluting this one?

Don, you very clearly have no understanding of the posts I have made. Please don't bother to reply until you do.

Thank you,

Correct, but it is not appropriate to hijack a thread. Doing that turns every group into s.e.d.

Correct that I don't own the group or the thread. I'm simply pointing out that in contrast to convention and courteous behavior, Don is trashing this thread.

LOL! How on earth do you bully anyone in a newsgroup? You are just being silly now.

I'm pretty sure Don is the only person I've been anything but polite to. That's because Don has been anything but polite. Don's posts have been like walking up to a couple of strangers on the street, having a conversation, and inviting himself to join in with comments that have nothing to do with what they were discussing. Not acceptable there, not acceptable here.

Sounds like you are the one with complaints that would make you want to kill file someone.

Bye

Oh stop it Rick. Your initial question - about board availability - was valid, you must have googled, not found anything and asked here; so far so good. Then you started talking about signal polarities, RS-232 standards etc., things most people here have leaned how to deal with 30 or so years ago. It does not get much lamer than that. And now you complain you got too much detail or whatever, eventually you discovered that only a wintel PC is your off the shelf option etc. etc. lame stuff. It was obvious after the first 2-3 posts you would not find what you initially asked for as being mass produced, why all the whining now.

No, YOU stop it!

Why do you feel you needed to post any of this? Why are you whining?

I suspect you have been in s.e.d. too long, and other groups too little. (To be fair, there's not a lot of traffic in many of the technical groups.) You are a polite and respectful poster by s.e.d. standards, but not by the standards of groups that remain technical.

I was turned off from joining in this thread by /your/ posts. Don's are easy to ignore. His posts are often long and somewhat off-topic, and people often skip them - that's not news to him or to anyone else here. Read them if you are interested, skip them if you are not.

Do you ever try reading the things you write? Perhaps trying to imagine how they might be viewed by others? Perhaps, like many bullies, you simply don't understand how you come across. Perhaps you really do view everyone else as though they are here to do your bidding and answer your questions.

Again, I think you are unaware of how Usenet works. It's more like a coffee shop, or an office water cooler. Don's the old guy who always seems to be there, sitting in the same seat. He's part of the conversation whether he posts or not. Some people are interested in the war stories he tells, others not - and for many, we find some of the things he says interesting, and some things less so. He has helped out a great many people over the decades, and I hope and expect he will continue to do so. /You/ are the one who wandered in here looking for help, and then chastise people for not concentrating fully on /your/ problems, or failing to read your mind regarding the answers you expect.

Don's posting behaviour is /entirely/ acceptable here. Yours is a lot more on the edge, which is why I am making these comments. The hope is that you will think a little about what you write, and moderate yourself

- then we can get back to politer technical discussions and enjoy their wanderings, wherever they may lead.

Because I do read the group and your lame whining is a bit excessive. Notice I kept silent before you got into abuse/whine mode. You have been a whiner ever since I know you on Usenet, decades by now. So I am not asking you to disappear, we are all different people, just to tone it down. You got *all* the answers to your questions here and you complain you got too much information. Either do the work you seem to be trying to do or just let it go, no more help for you here.