I would like to see some design files before I commit to something with so many promises.
I'm not sure what you are doing with UART that is so hardcore, but 3.3V FTDI cable covers all my requirements.The muArt is not about industrial or any "hardcore" usage. It is just one board that is universal enough to be used everywhere while giving you some comfort and handy features. I think the FTDI cable you mention is a very good example to support my campaign, actually. It might be robust enough, but each cable only supports a single voltage, and each cost about 22$. That is near the price for my board, but from FTDI you might need 3 of those cables (different voltages for different projects), so you've already spent over 65$, and you still don't get all the handy stuff from the muArt, like the DTR pin (needed for flashing ESP32 boards), the GPIOs, LED activity feedback etc. If your hardware projects are different enough, you will have 3-5 different converters in the end and have paid 70$, whereas you could just have bought a muArt. That is what this project is about, not about being hardcore. EDIT: The safety and robustness features are mostly just protection against common user mistakes that most other boards do not provide.
Sounds Interesting. I have been looking around for something like this for a reasonable price. What speed would we be looking at?. From my research galvanic isolation seems to limit the speed.
... and also no information about a working driver for Linux. If the latter does not exist, that'd be a big and serious no-go for me.
... and also no information about a working driver for Linux. If the latter does not exist, that'd be a big and serious no-go for me.
It shouldn't need one. Quoting from the landing page for the device from Holtek's website: "Communication Device Class (CDC) for communications and configuration". CDC class drivers are completely generic (by design) and I can't think of a major operating systems that doesn't natively support the CDC profile for a basic serial port straight out of the box. I'd want to test it before relying on that, because you can't be sure that they have implemented the standard properly, but if they have it should "just workTM".
@Everybody: Please do let me know if you are interested.
Mine generic non-insolated converters have better isolation than yours. Why? - They are inside heat shrink tubes. Due to offset USB connector and UART connector which is not edge-mount, your board is not compatible with heatshrink tubing.Mind you, we are talking about two different cases of isolation. The heatshrink tubing you refer to does not actually solve any of the problems the galvanic isolation in the muArt does. Galvanic isolation prevents dangerous voltages or high currents from reaching your host computer and isolates noise, a heatshrink does not do these. What the heatshrink does, it prevents damage (by ESD or shorts) to the uart-converter itself. Galvanic isolation protects not the converter, but you and everyhing else.
@Everybody: Please do let me know if you are interested.
Thank you, I am fine with non-isolated converters I have. Also I do not agree to "done right". Mine generic non-insolated converters have better isolation than yours. Why? - They are inside heat shrink tubes. Due to offset USB connector and UART connector which is not edge-mount, your board is not compatible with heatshrink tubing.
I think you're confusing insulation with [galvanic] isolation - the two are not the same thing.
Oh, and the heatshrink thing - what?. I hardly think that someone not explicitly designing their product to suit bodger's methods is a problem.
So put a 3D printed case on the thing.
Wrapping stuff in heatshrink fairly sucks.
Le sigh, USB still being used badly. >:(
Just tie shield and GND directly to GND. Only bad things happen by introducing impedance. Shield in particular should be tied to circuit ground plane as soon as possible, and in as many places as possible.
There are a few use cases where enclosure ground should be used to handle ESD, with a little isolation between that and internal ground, but such is the domain of experts. It's definitely not the way to handle a dongle, which is its own ground period.
(And yes, I wish I could address this towards whatever appnotes you read that promoted these exactly wrong ideas. Pass it on, if you will.)
Tim
I meant insulation indeed. Funny that my native language (which more or less obviously is not Englisch) does not have separate words for isolation/insulation.
I meant insulation indeed. Funny that my native language (which more or less obviously is not Englisch) does not have separate words for isolation/insulation.
How are we to know?
Case wise, using a potting box with the PCB as top cover (like Dave's µCurrent) would seem like a good and cheap solution.
I meant insulation indeed. Funny that my native language (which more or less obviously is not Englisch) does not have separate words for isolation/insulation.
How are we to know?
Educated guess that author of the post is not so dumb to imply that heat shrink adds galvanic isolation to the USB-UART interface? What remains is typo or illiteracy :)
Interface adapter shall be small and shall not mind top or bottom orientation. This is one reason why for stm32 playground projects I stopped to use J-Link but use cheap 3$ ST-Link knockoff instead. It takes virtually no space on the table, can be rotated as you (your device) wants. Thou said ST-link have metallic enclosure which is no good. Enclosure of interface converter shall be made completely out of insulator so you can drop it INTO live device w/o danger of shorting something and blowing-up.
On the topic of a case: yeah best would be to have one too, but the options are:You're applying an answer to a question. Having cases made doesn't have to be that expensive, even when numbers aren't huge. Calling conformal coating unreliable doesn't seem to coincide with practical experience.
- Let a case of my own be manufactured. Too expensive below 10.000pcs, so not an option.
- Design into an existing case. This would still need to be modified with cutouts for cables and windows for LEDs plus printing for labels. Also, the board is pretty small, so a standard case would make it a lot bulkier (and uglier).
- Design and 3D-print the case myself. First, I have no experience with mechanical design, and second I don't have a 3D printer.
- Ask for help in design, and share the design so that anybody can print their own case. This is not so bad, but most people still don't have a 3D printer, so only a few would be able to benefit from this solution.
- Apply heatshrink. Might not be "professional", but TBH it works, it is cheap, and is available for everybody. And as already pointed out, not so ugly as long as transparent.
- Apply conformal coating to the board. I think this could be workable as far as costs are concerned (though not so sure as it would require a 2-phase assembly), however, this is far too unreliable (abresion, thickness etc.), so I call my veto on this.
Summarizing, only heatshrinking works that I can readily ship to my backers. Having a public design for a custom 3D-printed case would be ultra-cool, but people would need to print it themselves. EDIT: Or, have a backer tier during the campaign where a printed case is included, but sold at a higher price.
Regarding the case, there are plenty of off-the-shelf cases designed for USB interfacing devices like this.Why insist on Digikey?
There's the rather cute one use by the ST-Link clones: https://www.sunrom.com/p/st-link-v2 (https://www.sunrom.com/p/st-link-v2) (anodised aluminium so has the potential insulation issue if it gets scratched), and they're already using the same connector as you are.
Similar plastic versions exist too. Just have a look at the many enclosures designed for USB memory sticks, some of them should suit your project.
Getting cases customised from Digikey is likely to be prohibitively expensive for a project like this.
You're applying an answer to a question. Having cases made doesn't have to be that expensive, even when numbers aren't huge. Calling conformal coating unreliable doesn't seem to coincide with practical experience.I am trying to be honest, if you are correct and I can make custom cases really cheap, then I just haven't found the right case manufacturer yet. But "cheap" is relative. Many would say 7$ for a custom case is cheap, but when the product without case would cost something between 20-30$, then that 7$ are expensive. I cannot incorporate that into the existing price because then I would be selling the thing below material costs, and increasing the price by the case's could easily take it over 30$, which a lot of people will find just simply too expensive for a UART converter.
If you want to pick a solution because you want that solution that's fine, but be honest with yourself about your reasons.
Digi-Key does value-add enclosures, FWIW. I haven't quoted them yet but it can't be too horrible. I'd think it's worth looking into for 100s+.
Case wise, using a potting box with the PCB as top cover (like Dave's µCurrent) would seem like a good and cheap solution. I've used that technique myself for low count projects (5 pieces), and I was happy with how it turned out. It certainly helps to mitigate ESD stuff and improves general mechanical robustness if you can't actually touch any circuitry and only the connectors are exposed.
No DSR? On adapter like this at minimum I'd like to see both CTS/RTS and DTR/DSR pairs, and ideally all signals...
Hi Pylo!
Can you share the name of the case manufacturer? I’ve been searching for a very long time for a suitable case manufacturer for a smallish project of mine, and the translucent design you have looks great!
Cheers,
Matt
Btw, for those of us that might maybe do something similar, i.e. a small run for some project that others might be interested in, would you be willing to talk a bit about the design process and costs for the case? At least for me it's surprising that a custom injection molded case is possible!
One thing I need for my project is a special connector (with ten contacts and a small screw thread) to be integrated into the case. Through your dealings with them, do you think this is something they might be able to accommodate?
What did you tell them that your minimum order count was going to be? I'm guessing a few hundred pieces, which means a high 3-digit sum for them overall as worst case?
And of course, you'll have my support once you launch your kickstarter ;)
I realise this is a bit pedantic, and I quite like the idea of your project... but you do realise it has nothing to do with a UART ?
In 95% of modern circuits, and 100% of traditional circuits - the UART functionality is within the controller or a dedicated peripheral chip.
One possible name could be... myUSBIO
As its functionality lies between the USB interface, and the serial i/o side of the UART/serial interface.
I realise this is a bit pedantic, and I quite like the idea of your project... but you do realise it has nothing to do with a UART ?
In 95% of modern circuits, and 100% of traditional circuits - the UART functionality is within the controller or a dedicated peripheral chip.
One possible name could be... myUSBIO
As its functionality lies between the USB interface, and the serial i/o side of the UART/serial interface.
Is there a processor within the device as you suggest? , or simply level converters & isolation?
hehe, I did say ‘pedantic’... ;)Your showing your young age :)
Have you ever designed a UART into a project ?
A significant part of a UART is the ‘shift registers’ to serialise and de-serialise the data either side of the ‘serial link’.
https://en.m.wikipedia.org/wiki/Universal_asynchronous_receiver-transmitter (https://en.m.wikipedia.org/wiki/Universal_asynchronous_receiver-transmitter)
Nowadays. this hardware is ‘hidden’ within a microcontroller (it’s still there), but a long time ago, the functionality was more obvious as an external peripheral chip.
https://en.m.wikipedia.org/wiki/16550_UART (https://en.m.wikipedia.org/wiki/16550_UART)
Aww. missed it again.
Was about to ask if if could be RS485 compatible
I really could use some cheap but reliable isolated RS485 interface ::)
And obviously it is a work of Art ;D
I’ve also received the first prototypes for the case, and I’ve got to say, I’m thoroughly impressed. Pictures are attached at the end of this post (note that the material used for the prototypes is some kind of epoxy, and it is not what the final cases will be made of – the final ones will be plastic, generally translucent, clear transparent in areas around labels, and will not have any of this yellow-ish color; see the rendering in the OP to get an idea).
I’ve also received the first prototypes for the case, and I’ve got to say, I’m thoroughly impressed. Pictures are attached at the end of this post (note that the material used for the prototypes is some kind of epoxy, and it is not what the final cases will be made of – the final ones will be plastic, generally translucent, clear transparent in areas around labels, and will not have any of this yellow-ish color; see the rendering in the OP to get an idea).
The enclosures of the front page of your campaign look even better. May I ask you who's making such nice custom enclosures for you?
The enclosures of the front page of your campaign look even better. May I ask you who's making such nice custom enclosures for you?
The details are all in this thread already.
https://www.tec4data.com/ (https://www.tec4data.com/)
Thank you. By the Web site, the company looks very expensive. Did they allow you to publish their final prices?
Do you have to add the VCC line to the target? (presumably to power the level converter)No prob :) Yes you need that, in the latest version of the board this pin's also been renamed to VIN to emphasize that this is an input pin. In my experience every prototyping board / SBC out there already has a header for GPIO or core voltage, so I prefer very much having to connect one wire more and then everything being automatically correct, instead of having to set voltages manually. And for your own custom boards you can either place this pin too, or in case you cannot, just supply it externally, but IMHO the latter is kind of rare.
Forgive me if it's mentioned somewhere, I haven't looked at everything.
Here's an interesting thing: I deliberately made the PWR LED only light up when both USB and VIN are connected. This way you can actually tell when the whole board's powered correctly, unlike with other converters where this LED simply signalizes USB connection but is actually useless because it doesn't mean power has been correctly applied everywhere.
Aaanyway, last week I posted a sample for your mailbag, with schematics and a preliminary datasheet. If there's a mail from Hungary, that's probably it :)
Congratulations, it's funded :-+
I've read your update on safety. I think it's a good idea to add to the discussion one more case - negative voltages. If they poke a ground wire into VIn then there will be negative voltages on other pins.
Would it be possible add to the CrowdSupply campaign/shop also the possibility to order the nice cable I see in the pictures, the one one with an IDC at on end and many dupont female connectors, each marked with a tag, on the other end?
I know that some of you hold a grudge against FTDI, but I see no other alternative to the CP2102N as long as I want to deliver the features originally promised in the campaign.
I never want to see another FTDI part ever again. but still backed it.
There is alternative, but most likely you will not love it: microcontroller with USB interface.
There is alternative, but most likely you will not love it: microcontroller with USB interface.
It is technically an alternative, but probably no one would like it unless the FW to that uC is the product itself.
Case in point, SiLabs for one could not get it right - I have reasons to believe that the CP2102N that I had to replace is secretly an LPC microcontroller in bubblewrap.
No, unless you're using LPC in a generic sense instead of referring to the Philips/NXP ARM product line. There's strong evidence to suggest that the CP2102N is a pre-programmed EFM8 which would make a lot more sense as they are both from Silicon Labs.
We managed to obtain a used mold and modified it for the muArt's enclosure. It cost me about 2.2k$ one-time, plus the cases are 0.6/piece at an MOQ of 1000. These are solely production costs. As for tec4data's engineering services, we'll work together on other projects (bartered).
Hello @pylo
something new ?
As for the M/F jumper cable - eh, I guess you're right, but you're not meeting the standard you set for yourself there, seeing how it doesn't have a 2x5 connector attached, nor labelling. As it is, I'll prefer to attach M/M jumpers to the F/F cable to gender change it, that way I can make use of the labels and keyed connector. But whatever, it's a small thing, don't worry about it.
All in all, congratulations on doing a successful campaign, on time (almost) and on budget (I assume), and shipping a quality product. :-+ You made it look like you've done this before a 100 times. So is there anything you'd do differently with hindsight?
I have a strange problem
I have a strange problem
For particular (isolated) uart adapter TX, RX and GND connection is not enough. VCC shall be connected/supplied as well.
In your pictures, it seems you connected TX/RX wrong. E.g. you connected the µArt's TX to the Linksys's boards TX, but correctly TX should connect to RX and vice-versa (unless this router is one of those with unusual and insane "swapped" RX/TX labeling).