Ubiquitous Successful Bus: Version 3

USB 2 is the USB we all know and love. But about ten years ago, USB got an upgrade: USB 3.0. And it’s a lot faster. It started off ten times the speed of USB 2, with 5 Gbps, and later got 20 Gbps and 40 Gbps revisions. How does that work, and how do you hack on it? Well, for a start, it’s very different from USB 2, and the hacking differs in many important ways.

In fact, USB 3 is an entirely separate interface from USB 2, and it does not depend on USB 2 in any way whatsoever – some people think that USB 3 negotiation happens through USB 2, but that’s a complete myth. USB 2 and USB 3 are electrically, physically, and logically distinct interfaces. Except for the fact that USB 3 is backwards compatible with USB 2, they are simply entirely different.

This also means that every USB-A port with USB 3 capabilities (typically blue, but not always) carries two interfaces; indeed, if you want, you can split a typical USB 3 port into a USB 3-only USB-A port and a USB 2-only USB-A port. USB 3-only ports are not legal per USB 3 standard, you’re expected to keep USB 2 there, but only for user convenience; you can split it with a hub and get, like, three extra USB 2 branches for your own use. Even if it’s forbidden, it works flawlessly – it’s what I’m currently using to connect my mouse to my laptop as I’m typing this!

Not to say that USB 3 is all easy to work with – there’s a fair bit of complexity.

For A More Civilized Age

USB 3 is fully differential, and full duplex. It’s still point-to-point, but unlike USB 2 with its pseudodifferential half-duplex transmitters, there are two differential pairs – one RX, one TX. It’s like UART: TX on one end connects to RX on the other end, RX connects to TX, so the two pairs have to be crossed over, typically, inside the cable – for instance, high-speed USB-C cables have the USB 3-intended pairs crossed-over by default! Oh, and you have to put series capacitors on each end, at each TX output.

By [Unconventional2], CC BY-SA 4.0
In this way, USB 3 physical layer is just like PCIe; in fact, it can be done using basically the same hardware inside the chip! The routing requirements are tougher than USB 2, so you really want to make sure the tracks are impedance-matched, and use a four-layer PCB instead of a two-layer one. Wondering about routing USB 3? Refer to my guide on routing PCIe, keeping the above restrictions in mind. Here’s a bonus – unlike USB 2, you can flip the pair polarity for ease of routing!

Device detection isn’t done with resistors – instead, the USB 3 peripheral produces regular pulses on the TX pair, known as LPFS mode, and the peripheral on the other end listens to the RX pair for these pulses. That’s also how polarity flips get compensated for.

There are no resistors to add, though if you want to connect different USB 3 devices on your board, you might need to take care of some common mode level matching every now and then, like niconico shows us in detail in the extensive readme for their wonderful PCB housing a USB 2 – USB 3 transaction translator.

Just like PCIe, you’re not expected to handle USB 3 yourself. Unlike USB 2, you can’t quite hand-wire it either – there are products of Eastern manufacture that do, and the failures are quite prominent. If you are shopping for USB 3 hubs and find one with a captive cable, be careful – it might be wired in a lax way, neglecting USB 3 requirements, and you won’t be able to fix it without buying a new hub. Better stick to USB 3 hubs equipped with microUSB3  and USB-C ports!

If you want your links to work guaranteed, don’t hand-wire them, rather, use impedance-matched traces on your PCB as much as possible, PCB track quality really matters here, and could easily limit your speed; even big companies might screw it up!

For instance, [WifiCable] has tinkered on a laptop with USB 3 ports limited to 5 Gbps mode by a chipset setting, and once the setting was unlocked, the ports would negotiate 10 Gbps mode, but had constant stability issues. I’ve also seen Dell route a USB 3 link over an FPC, only to get stability issues with certain kinds of hubs.

The Three Versions

You might have heard of the USB 3 naming shenanigans, with like fifteen different names and logos used to refer to different USB3 versions – like USB 3.0 USB 3.1, USB 3.1 Gen 2, USB 3.2, and so on. I am pleased to inform you there are only three versions – the dozen different names and logos are duplicates of each other, a marketing strategy that confused people more than it helped, nothing more. If you want to learn more about how it came, you can read here, but let’s be fair, you likely don’t need to know that.

These are as big as they look, and haven’t really caught on. by [Anil Öztas], CC BY-SA 4.0
There are only three USB 3 versions as far as cold hard hacking is concerned – you can refer to them as 5 Gbps, 10 Gbps, and 20 Gbps. The 10G bps is just 5 Gbps but overclocked in a few different ways. The 20 Gbps version requires USB-C, and, to simplify it, is like two USB 3 links ganged together. You can’t just put two links together to get 20 Gbps mode, though – it does require a different USB 3 peripheral, and it doesn’t work like two USB3 links, even though it has backwards compatibility.

As for matters more physical, there’s four different connectors you will see USB 3 on – USB-A, USB-B, microUSB 3, and USB-C, each of them getting extra two pairs of pins, and, for the first three, an extra GND pin. This GND line helps provide a more stable ground reference, is perhaps not as much encumbered by the ground current, and with the GND pin placed between the two pairs, it helps prevent crosstalk. USB-A is used on hosts, USB-B and microUSB3 are mainstays on devices, and USB-C, in its universality, can be used everywhere.

remember, microUSB3 is backwards compatible with microUSB cables! By [William.wl.li], CC BY-SA 4.0
On some devices of Eastern manufacture, in the dark days before USB-C, you might have seen USB-A used as a device port, and the devices would come bundled with the forbidden USB A-to-A cable. MicroUSB3 has the reputation for being finicky, and USB-B 3 is quite bulky, to the point where not all devices could even afford the added height. If you’re in a pinch and you need a USB 3 device port, you can still use USB-A – people will call it cursed, but you might as well wear this badge proudly.

Nowadays, if USB-C isn’t an option because you can’t be bothered to find a mux, a device with microUSB3 would be my second choice. The trick is to buy a few USB-C to microUSB3 cables on Aliexpress. I swear by them, and if you have some microUSB3 devices at home, you should grab two or three cables like that and never worry about microUSB3 again. Not that the forbidden A-A cable is hard to find nowadays, either!

Last thing to mention is, you might see USB 3 cables and sockets in an initially unexpected place – carrying a PCIe x1 link, again, in hardware of Eastern design. USB 3 cables are only used there for the extra lines: USB 2 pins carry REFCLK, and the two high-speed pairs carry, DRAIN typically carries GND, and the USB2 VBUS and GND tend to carry two PCIe link management signals.

This is an unspoken standard across Eastern vendors of many PCIe accessories – you might see slight pinout variations, but nothing too major. Honestly, I respect that a lot, I’ve recommended it to my hardware hacker friends as a way to expose PCIe, and it’s something that I believe is a decent option, especially given the abundance of hardware that uses USB 3 connectors for PCIe. Is it standards compliant? No. Could someone call it cursed? Yes. Is it a viable way to carry a PCIe x1 link? Also yes. Is it easy to implement? Yes, again. Is it cheap? Without a doubt. If you really need x4 and guaranteed high speeds, you might want to go for Oculink, but until then, the abusing USB 3 hardware will do just fine.

There’s more I could say about USB 3, but for now, I hope this is more than sufficient for you to wade through USB 3 waters, for whatever hacks and projects you might be exploring. Got questions, corrections, or advice? Ever make something cool with USB 3? Tell us all in the comments down  below!

60 thoughts on “Ubiquitous Successful Bus: Version 3

  1. thanks – the existence of USB-A 3 and USB-B 3 and microUSB 3 is news to me. stared at the USB-A photo with the extra pins for a good long while before i could believe it wasn’t an AI-generated joke! reminds me of the cheap camera i have with a combined male usb-a / microusb connector. kind of unsettling. i like to think i could have gone my whole life without learning about USB-A 3, and i hope by the time i die i may yet feel like i’ve accomplished that

    i’m not sure the downsides of USB-C but in user devices i like it at least as well as i liked microusb before it. especially given i can still just use microusb if i want to

    1. “combined male usb-a / microusb connector” Wait what?
      I do have a device that has a female micro-usb-a/b connector. They are basically the same, with the female micro b what most of us know (the USB on phones before USB-C) and USB-A the same but with square corners instead of 2 diagonal ones. A female-micro-usb-a-receptable will fit a usb-micro-b cable. They are “illegal” ports, but are used fairly often on e-bikes and UPS’es, where they can be used both in client mode (attached to a computer with a normal cable) to change the bike’s settings or firmware, but also as a “host” (charge only) to charge attached devices with a male-usb-micro-a (or b) to male-usb-b-micro cable.

          1. Wow, didn’t know Powered USB was a standard, I’ve got a couple HP touchscreen DisplayPort screens and they have this on one end of the power/USB cable. Now I know what it is XD

  2. “On some devices of Eastern manufacture, in the dark days before USB-C, you might have seen USB-A used as a device port, and the devices would come bundled with the forbidden USB A-to-A cable.”

    Oh ho ho, it ain’t just Eastern manufacture.

    In aerospace/military/etc., the “circular connector” or “mil-spec” standard that is essentially D38999 also resulted in a bunch of manufacturers using the same connector sizes for “non-standard” mil-specs, like Ethernet or USB.

    So you get these “mil-spec style USB connectors” from a ton of the ‘standard’ vendors (Glenair, Amphenol, etc.). They’re super-pricey, too, like $100+ (as high as $500+!). And some of them are bulkhead feedthroughs, so USB connectors on both sides.

    And you know what they all are? A to A. Yes. Seriously. Military precision, there.

    1. Ooh, I found a nice link!

      https://www.digikey.com/en/product-highlight/a/amphenol-pcd/usbftv-and-usb3ftv-ruggedized-usb-connectors

      Go glance through. Literally everything is USB type A. Bulkhead feedthroughs are A to A (or A to 4 pins), literally all the cables are A to A, everything. And some of these are even USB3 Type A-to-A! Some are A receptacle to A plug, so that’s not horrible, but overall it’s like they looked at the USB standard and said “nope.”

    2. i believe i have had exactly two devices that were a-to-a. one was a cheap avr programmer. the other was the archos media player i had 20+ years ago. i can understand the former, but not the latter.

  3. If USB 3-only ports are not legal per USB 3 standard, what about USB3 with USB1 ?
    (some IC’s only implement USB1, because of the diespace useage for USB2)

    and is USBC CC-pin backwards compatible with micro-USBs USB-ID pin?

    Also is the algoritm for 128b/132b is somehow compatible with 128b/130b? and 64b66b? and 8b10b?
    and is PAM-2/NRZ, PAM-3 ,PAM-4 and PAM-16 related enough to be combined to one hardware unit?
    or does they all require defferent hardware implementations?

    1. “USB1” is a subset of USB2, that’s the whole “USB2 full-speed/low-speed” thing. USB2 100% includes devices that are FS/LS only.

      “and is USBC CC-pin backwards compatible with micro-USBs USB-ID pin?”

      No, not in the slightest.

      1. Yes, in theory a USB2 port can have a USB1 keyboard or mouse connected. USB1 low speed devices were required to have a captive cable.

        The gotcha is that the USB2 controller (EHCI) in fact doesn’t run at USB1 speeds. USB1 speeds are low speed 1.5Mbps and full speed 12Mbps https://en.wikipedia.org/wiki/USB#USB_1.x

        It’s typically fine on PCs because the USB2 controller is hard-wired to a USB2 hub. And USB2 hubs are required to have a Transaction Translator. The Transaction Translator’s only job is to buffer USB1 transactions and then spew them at USB2 speeds, keeping the rest of the USB2 devices happily running at 480 Mbps. Old, old PCs had a USB2 controller and a Companion Controller, which was a USB1 controller behind a mux, and the USB2 controller would flip the mux over to the USB1 controller if some slow device was plugged in.

        It’s typically going to bite you if you use USB2 on a small ARM or ESP32 or AVR microcontroller, where you only have the USB2 controller but no hub. It’s normal for these SBCs have the hub built-in, but sometimes you find out that the manufacturer shaved a few pennies and neither USB1 solution made it into the design. No hub, no companion controller, meaning no USB1.

        1. Yeah, but then you just plug it into an external USB2 hub, which automatically includes the TT, and you’re fine. The TT isn’t really a buffer – it’s essentially a USB1 host which responds to split requests from the USB2 host.

          The same thing doesn’t work with USB3, which is why USB3 hosts are required to support USB2.

    2. USB3&USB1: don’t know about the standard, but nothing would restrict it in practice for sure. As for ID pin – no, sadly, the ID pin is a mishmash of simple open and complicated proprietary signaling, so I gotta say it’s best left in the past.

  4. I never knew it was called microUSB3. We got external 2.5″ SATA drives with those connectors and never knew the name. Learned something new today!

    The USB standard has become very confusing. I’m glad I don’t use it all that much. Especially when trying to do things like connect monitors or support high-power devices, it can get very unclear which devices work in which ways. For a while, I was looking for a way to move my computers further from my workstation, maybe into a cabinet or another room, but it seems that’s not possible at a reasonable price. Once you start looking into 10-meter cables to connect multiple monitors, it becomes a real challenge.

    P.S. It was confusing to see eastern written as Eastern given the context. I first assumed it was about a company named Eastern so I was already googling that. Reminds me of an old English lessons though. “Anything eastern of Lubeck is Eastern Europe”. Not trying to be annoying, just hope it helps other people who got confused.

    1. “but it seems that’s not possible at a reasonable price. Once you start looking into 10-meter cables”

      This isn’t a USB problem, it’s a bandwidth problem. You’re trying to push gigabits/sec over tens of meters, that’s always going to be a challenge. USB Type C, HDMI, DisplayPort, whatever, pretty much anything over 10+ ft-ish is going to Be Hard (not impossible, it’s totally doable, but it’s not surprising when 5+ meter cables don’t work for certain devices). Ethernet spoils you because there’s sooo much more going on inside the PHYs.

        1. Yeah, it’s fairly nuts to think that there are multiple interleaved ADCs sampling at a good fraction of a gigasample inside a 10 GbE receiver and you can just… buy them for under a hundred bucks.

          like… where is my $100 10 GSa/s scope, people

    2. Basically USB before USB C is golden. If the connector fits and the color matches, it will work, but might work at slower speeds.
      With USB C you need the right combination of two devices and cable, and there is NO way to tell (without testing equipment) whether they are the right combination.

      1. Usually there are cryptic glyphs, but now it says “USB4”.

        It gets worse. I have an HP BlizzardU motherboard here with dual USB4 ports, and even HPs (now removed, thank you Archive .org) website says it has no support for onboard video output. Well guess what, the top connector has DisplayPort Alt mode. Which is good because the BIOS will only display a white screen on a normal video card. Seems to be an HP thing, had an AM5 HP board doing the same thing last month.

        Also thanks a lot, I forked over $8 to Amazon and I’ll have a pair of USB3 to USB2 and 3 breakout cables

      2. “If the connector fits and the color matches, it will work, but might work at slower speeds.”

        Almost. USB OTG started to break things because there’s nothing stopping you from plugging in an OTG cable in and hooking up, say, a mouse to a mouse, and that ain’t gonna do crap.

        USB started off as “two separate port types, but it’ll always work” and it eventually evolved into “one port type to rule them all but only a chance it’ll work.”

          1. It’s just the idea that originally USB was almost, almost universal – you plug it in, it’s going to work, regardless of speed. There are a few edge cases where it didn’t quite work, but for the most part, plug in = work.

            That started to fall apart as USB started to be used for a billion other things, and by the time of USB3/USB-C it’s very much not true anymore.

      3. Not that intense in the slightest. Most USB-C devices are charging-only or USB-2 only, so any cable works, and any host port will do. If it’s a device that does high-speed data transfer, use a thick cable that does like Thunderbolt or DisplayPort, and make sure your host port can do these. If it’s about charging or powering high-power devices (over 60W, laptops and such), you pick a cable that can do 100W or 240W. Know no fear c:

        1. Most USB-C devices really are not charging or USB-2 only dumb cables are fine… If anything the vast majority are least 5gbs or greater for the most basic functionality, many actively require at least some of the alt-mode features and/or require chipped cables as its getting used for more and more things that should never ever have been USB powered…
          Heck it has become the only port many computers come with! And a huge number of displays are USB-C for power and data etc.

          Maybe the bulk of hacker dev boards and the like are only using it for power and/or USB-2 but even the bulk of very cheap phones I’ve looked at recently do alt-mode display and at least 5gbs (though not all of them document what they port can actually bloody do, so thanks to the wonders of the ‘standard’ you have no idea if a device will support anything without actually trying it)…

    3. “I never knew it was called microUSB3. We got external 2.5″ SATA drives with those connectors and never knew the name. ”

      I also had a SwampScum Galaxy phone that used them as well, I’m not sure if it charged any faster with it.

  5. Are there any microcontrollers below EUR 10 that can do > 480Mbps USB?
    The Cypress CY7C68013A (Popular in the ubiquitous 8ch 24MHz Logic Analyzer) “only” goes up to 480Mbps, and the FX3 is quite a lot more expensive.

    All this talk about higher speed USB is nice, but as long as it’s difficult to obtain affordable hardware, it’s not so much fun to experiment with it.

    A bit similar with 10Gbps Ethernet. It has been available for 10 or so years, but it’s still quite expensive. I just had a look and apparently a 10Gbps switch is about 20x more costly then a 1Gbps switch, and I find it hard to believe that would be the “real” cost, instead of some inflated cartel conspiracy thing.

    1. ” I just had a look and apparently a 10Gbps switch is about 20x more costly then a 1Gbps switch, and I find it hard to believe that would be the “real” cost”

      I don’t. Analog-wise the requirements for 10 GbE are pretty much 10x+ the cost of gigabit ethernet, since GbE basically hits the limit of single ADCs per channel.

      And then for a switch, if you just look at shuffling bits around after the PHY, a RGMII interface takes just 14 pins, with data DDR at 125 MHz: you could build a gigabit switch with a pretty cheap FPGA. 10 GbE switches basically require decent SerDeses, or nearly 6x the pin count, and including a SerDes is a significant jump complexity-wise.

      There are FPGA Ethernet switch (NetFPGA) and NIC (corundum) out there, and the requirements jump from GigE to 10 GbE is huge.

      So if intrinsically they’re around ~10x more expensive, add in the fact that the demand is significantly lower, and 20x makes complete sense.

    2. i think the silver lining here is that extremely high speed usb-c is handy (only) when you need it to be. i can’t get an rp2040 pico board that speaks 5Gbits/s, but i can’t hardly imagine it processing that much data anyways. but if i were to go shopping for SATA HDD enclosures, where that speed might actually be useful, i can find a lot of them purporting to use the higher speeds.

      it’s similar to why it’s not such a big deal that the endpoints can have a wide variety of features…it’s like M2…if i were to put an M2 device in my PC, it would probably be flash storage, and my motherboard manufacturer knows that so it supports NVME. the M2 device in my laptop is wifi, so my laptop supports pcie x1 over M2. i only have to test the edges of those slots’ capabilities if i wanted to do something whacky like install a tiny wifi board in my PC or sacrifice wifi for expanded storage in my laptop.

      my point is, the lack of features you don’t want isn’t particularly concerning…generally vendors do a good job of filling in the features you do want, in usb-c and everywhere. it doesn’t matter so much if each product (or spec) perfectly anticipates all possible uses, so long as in practice the real needs are fulfilled.

      1. It’d be wonderful if USB3-to-USB2 hubs existed.

        No, not those. Or those. Probably not those either. Almost all “USB C to USB 2.0 ports” hubs are just USB 2.0 hubs with a USB C connector – the USB spec doesn’t call out transaction translators for 3->2 like they did for HS->FS/LS, so chips like this guy: https://hackaday.com/2022/03/07/a-chip-to-address-the-fundamental-usb-3-0-deficiency are “special” and don’t always work.

        Yes, it’s hard to imagine cheap microcontrollers pushing much past 20-30 MB/s. It’s not hard to imagine 5 of them doing so, and given that laptops have moved to “let’s get rid of all of our USB ports” it’s… not fun.

        So if you want to say “USB 3 would be great if the designers weren’t idiots,” that’d be what you would point to.

    3. There is some not expencive MCU with USB3 and it is CH569 (from WCH) 7~10Eur, and development board with it ~30Eur. What would be great is to have firmware similar to fx2lafw (from Sigrok), I’m sure that MCU could handle it with much better capture rate and more pins in parallel.

  6. Well that’s useful to know, I didn’t realise the dual row USB 3 ports were actually 2 ports a in one, that potentially solves a bunch of space issues I have with a Raspberry Pi 3 that needs more ports.

  7. The problem with the variations on USB 3 isn’t that there’s too many names for the same thing, it’s that there’s too many things under the same name and connector.

    I have a laptop, a cellphone, and two pairs of wireless headphones that all charge off of a USB-C connector. Obviously I can’t run laptop off the cellphone charger because it’s not powerful enough, but why can’t I charge my cellphone off of the laptop charger? (Really, the cellphone charger should still be able to charge the laptop while its sleeping, because it delivers 20 Watts, enough to charge the battery in hours, not days.)

    On top of that, one pair of my headphones also charges off of the cellphone charger and not the laptop charger, but the other pair will charge off the laptop charger but not the cellphone charger!

    The problem isn’t limited to power delivery; I also have a slew USB-C to USB-C cables that aren’t cross compatible for data connections, with no clear way to know which will work when. Last I checked, not counting power delivery or active cables, there were six different kinds of USB-C to USB-C cables.

        1. The SBU pair can be “used” as a differential pair but it isn’t differential – it’s got weak impedance control (not as bad as the CC pin, but bad) by spec. I’m guessing by “one more” you mean the Vconn/CC pair, which would work except with an active cable.

          The 4 high speed pairs are shielded and impedance controlled (at 90 ohms, though), the USB2 pair is also impedance controlled, but unshielded.

    1. it sounds like you’re living the disaster that is still only hypothetical in my mind.

      i’m surprised your pile doesn’t just degrade to trickle charging. i have a whole mess of proprietary micro usb fast chargers but i can mix and match them at will so long as i don’t mind that it takes like 6 hours to charge my phone.

    2. I’ve encountered this too, and it’s part a relic of the early days of USB-C PD, and manufacturers not being as compliant as they could be.

      One of my USB-C laptop power supplies will only negotiate 20v power, despite the fact it could likely deliver 5v, 9v, 12v and 15v. Why? Probably because people still think of ‘phone charger’ and ‘laptop charger’ as distinct devices, and there is no business motivation to offer a product that can do both if you can instead sell two products.

      There were also a slew of proprietary ‘fast charging’ technologies competing before USB-C PD was firmly established that slowed broader compatibility.

      Now that USB-C PD is established and growing, it is possible to live the dream we were promised. I recently purchased a desktop 100w USB-C PD supply that fast charge my phone at 9-15v, laptop at 15-20v, and dozens of other devices with the same USB-C PD cable.

      I have had to toss a number non-compliant ‘USB-C’ power supplies and cables along the way, but that’s quite often the case with emerging technology.

      1. Quick note – if you’re not talking about a “20V constantly supplied” USB-C firestarter PSU, it’s nigh certain your PSU can deliver 5V – that’s basically a requirement for it to even function with proper USB-C ports, and devices will go up in flames if it doesn’t. Mind you, 5V operation is just “as soon as a 5.1k pulldown has been detected on the other end”. So, either it can actually do 5V, or you have an actively dangerous PSU.

    3. why can’t I charge my cellphone off of the laptop charger?

      You can’t? I do that routinely – that’s like, one of the major cool parts of USB-C. I also charge my laptop off my phone charger sometimes, 20-30W isn’t as fast of a charge but it’s generally good enough. Not all laptops support this, but many do. Some headphones and other devices require BS, but 1) it’s rare, and 2) not really a failing of USB-C itself, just a mfg implementing things in a boneheaded way.

      the cellphone charger should still be able to charge the laptop while its sleeping

      not all of them do but this is actually an existing feature with USB-C. My Framework can sure charge that way.

      I also have a slew USB-C to USB-C cables that aren’t cross compatible for data connections

      To be clear, if your USB-C cable can’t do any data, it’s probably broken; USB2 (and 60W aka 3A) is the minimum all cables are obligated to do. Not all cables support USB3/DisplayPort/Thunderbolt, those cables require extra pairs and are more expensive – see if your OS complains about an unsuitable cable. My advice – if your cable isn’t labelled with the extra things it supports compared to USB2/60W, label it, helps fix majority of the cable distinguishing issues possible.

    4. Sounds like you’re doing something wrong or lucked out and got completely incompatible equipment somehow.

      I’ve never had an issue (that’s a lie) with USB-C. Sure it can be a bit of a gamble knowing what current a random cable supports but some devices will report cable capabilities. My Macbook (that has a 140W charger) can trickle charge from a 15W supply. it does what it can with the 15W without complaining. I can charge phones from the Macbook as well as from the Macbook charger.

      The only issue I had with USB-C is when occasionally the Macbook decides to charge itself from the phone, and the phone willingly acts as a charger. You can’t really say that’s a bug though as both can act as a source and a sink so who decides what should do what?

      1. afaict the “who’s charging who” is a bug, and really, it’s a user experience flaw. IMO the user always ought to have choice in this matter – many an OS provides such a choice, too. ig we need more OS makers to catch up with the times and add the necessary APIs&dialogs!

  8. Better stick to USB 3 hubs equipped with microUSB3 and USB-C ports

    NOOOO that microUSB3 port and connector is plain unsuitable to use, the most fragile useless port I’ve ever experienced. So get a decent USB-A or B USB3 connector over that one every day! As even if you never ever move or cycle that MicroUSB3 cable or port (as in its hot glued together inside a project) it will still break on you. So actually using it for a normal day to day USB hub…..

    Much as I hate USB-C I’d still take USB-C over the micro USB3 port if I get any choice… The USB-C spec is perhaps the worst ever made on the KISS principle, or even just basic expectation of electrical function, but at least it is mechanically about as good as any similar connector that small.

    1. Disagree. It’s a pretty simple equation – the hubs with your preferred connectors are obscure, and therefore more likely to be wonky. Also, definitely not my experience with microUSB3 – it can absolutely last. The trick I found, is buying a whole bunch USB-C to microUSB3 cables from Aliexpress – I put a good few of them through severe abuse (seriously, a lot of abuse) and it was a while before they broke. Oh, and external HDDs used to come with decent microUSB3 cables, can recommend those too.

      1. The long thin blade of MicoUSB3 is really insanely delicate for on the move use, and the port in the device is usually terrible too – you want a port that will rip off the board trivially no matter how much work you do to support it it is the MicoUSB3 sockets you want to choose – it is just terrible port compared to the rest of the USB options. The regular Micro isn’t all that well loved and its an absolute tank in comparison.

        Also if ‘the trick’ is buying huge numbers of cables you are basically saying ‘its kinda crappy so I need lots of cables just in case’, but because I have lots of cables it was never a problem… Not a ringing endorsement…

        1. I’ve used a few microUSB3 devices on the daily – a Galaxy S5 constantly riding in my backpack as a hotspot, and like three of my external HDDs/SSDs. The latches on the USB-C to microUSB3 cables I used, were pretty damn good, to the point I could hang my Galaxy S5 off them; now that I remember, I did that a lot because I had to. No broken microUSB3 ports at any point, some broken cables but all of them lasted well for their money. IME what you’re talking about, really depends on whether the microUSB3 port has through-holes for the shield, how well it’s supported by the case – straight up, just microUSB kinda problems, since microUSB also hugely benefits from using a through-hole shield port and case support. Most importantly, by no means is microUSB “an absolute tank” – I’ve had to repair tons of microUSB ports, even on devices I myself manufactured with them, but never have I had to repair a microUSB3 port so far. I don’t think many people will share the “absolute tank” assessment with you, either!

          The thing about buying lots of cables, is that afaict with microUSB and beyond, the cables are designed to break before the port does. As long as the port isn’t SMD-only, that far indeed is true. Something has to give after daily stress, with miniUSB it was device ports, and starting from microUSB, it’s been cables. So, yeah, it’s an endorsement – the standard is decently designed to protect device ports from daily wear and tear, sacrificing the cable in dangerous situations instead. As far as I can tell, that’s what you want to happen when push comes to shove.

          1. In comparison to microUSB3 the narrow normal micro ones are tanks – vastly more durable mechanically, I didn’t say they were actually good! Only that in comparison to the already maligned USB2 version the USB3 has more durability issues, which isn’t a shocker when you have bodged a second connector with a really thin joint between the two so they can pretend to be one connector…

            Both types of micro are fine while they work, and the retention features that family of USB comes with is IMO a good feature over USB-C for most uses. But even then if you want to buy something new get something with an actually durable port, so don’t get microUSB3. If you can find A or B take that, if not take USB-C. Much as despite USB-C it its a fast and durable connector in a way microUSB3 is not.

            (Also not actually that unusual to see B or A ports they are still the default connectors of choice it seems for almost all the more professional grade hardware large enough to actually fit one (which is almost everything))

    2. I had a Micro USB 3.0 connector break away from an SDR. Lucky there was no damage and I could repair it easily. Screw those things! I’ll take normal, large, or mini over USB Micro.
      Glad to see they’ve switched to using the larger Standard-B connector in the newer revision of the device.

      1. that’s basically the microUSB failure mode =D solder it back, epoxy over the connector shell, and keep using it. USB-B-3 has its own problems – for a start, it’s very bulky, so it’s going to drag your device around the cable, which is also a failure mode given the stress it puts on the device attached and the possible fault conditions (“board fell off the desk”/”levered into a piece of metal and short-circuited”/”antennas broke off”)it introduces. Really, a USB-C port is the solution here – for USB3 purposes, you only need a single mux chip with integrated CC handling, plenty of those around by now.

        1. As USB-C cables that actually do USB3 speeds are likely to be thicker and stiffer than the USB3 B cables, or at best identical*… Really the USB-C port is hardly better at dragging the device around, just because the connector on a USB B is larger doesn’t mean the cable ends up more difficult to deal with.

          And being a much much smaller footprint connector that is usually only surface mounted the USB-C more likely to rip right off the board maybe taking some traces with it if your in the situation of the cable putting forces on the board. So when compared to the usually through soldered outer shell of the B connector that gives such a solid mechanical linkage to the PCB….

          *obviously no hard and fast rules, you can get quite flexible or extra chunky in both

  9. As a consumer I had many problems with the USB2 micro connector. The female on a mobile or headset/phone would get bent pins and fail, the male micro connectors on cords would do the same. One damaged male terminator, say a bent pin with a bit of dust could be the last damage a device female connector would tolerate as the last insertion then fail.

    The flippable insertion causes much less collateral damage to both make and female To clarify my experience was almost exclusivity charging. When I’d zoom in to look at the wreckage left in a female connector on a Samsung. Phone it was a mess, usually the data pins were damaged or gone as well.

    Also had micro/female connectors lift right off headphones, the urge to mate overcame their solder foundations, apparently.

    I had zero simular failures on mini-USB and none on the reversible C/3 version. Sorry for not using the proper 3/C designations, I tried to learn them a few times and gave up.

    On the other hand, this dumb user noticed something smoking on my bathroom cabinet one day. It was a (generic) Lightening cable plugged into a charger with only dry air at the flat reversible end. The cable has shorted somehow inside the cable 10 mm from the reversible end then melted up to the end. Smoldering. That got my attention and I quickly notified the cable vendor, through Amazon, if that ever works. So I won’t miss those.

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