Comment by mort96
5 hours ago
All these USB version names. I used to know what they all meant, but then the USB IF went ahead and renamed them all and made a bunch of versions have the same name and renamed some versions to have the same name as the old name of other versions.
I have absolutely no idea what anyone means when they say USB 3.2 gen 2x2. I used to know what USB 3.2 meant but it's certainly not that.
Unfortunately "USB 3.2" is just a version of the standard, which does not give any information about the performance of a USB port or device.
USB 5 Gb/s = USB 3.2 gen 1, available on Type A or Type C connectors (or on devices on a special extended micro B connector)
USB 10 Gb/s = USB 3.2 gen 2, available on Type A or Type C connectors
USB 20 Gb/s = USB 3.2 gen 2x2, available only on Type C connectors
Moreover, "5 Gb/s" is a marketing lie. The so-called USB of 5 Gb/s has a speed of 4 Gb/s (the same as PCIe 2.0). On the other hand, 10 Gb/s and 20 Gb/s, have the claimed speeds, so USB of 10 Gb/s is 2.5 times faster than USB of 5 Gb/s, not 2 times faster.
10 Gb/s USB and Ethernet have truly the same speed, but the USB overhead is somewhat higher, leading to a somewhat lower speed. However, the speed shown in TFA, not much higher than 7 Gb/s seems too low, and it may be caused by the Windows drivers. It is possible that on other operating systems, e.g. Linux, one can get a higher transfer speed.
The fact that you had to list all of the versions and speeds at the top of your post is illustrative of what the parent was trying to say. We can all look up what speed is associated with what version, but it’s not exactly a consumer friendly experience.
A few computer manufacturers do the right thing and they mark the speed on the USB ports, removing ambiguities, for example ASUS does this on my NUCs and motherboards.
Unfortunately, there are too many who do not do this, even among the biggest computer vendors.
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Oh, it's fine.
The lack of clarity is in keeping with the USB C connector itself, which may supply or accept power at various rates or not at all, may be fast or slow, may provide or accept video or not, and may even provide an interpretation of PCI Express but probably doesn't.
It probably looks the same no matter what, and the cable selected to use probably also won't be very forthcoming with its capabilities either.
(Be sure to drink your Ovaltine.)
The USB A connector stayed the same between USB 1, 2 and 3. Yet most manufacturers voluntary distinguished them by giving USB 1 and 1.1 a white insert in plug and port, USB 2 a black insert and USB 3 a blue one
This was neither standarized nor enforced, yet it worked remarkably well in the real world
Then we decided to just have no markings at all on USB C cables. On the ports at least we occasionally get little thunderbolt or power symbols
The exterior of the USB A connector stayed the same. The number of pins increased when we went from USB 2 to 3. So, even in this case, it’s slightly more complicated. The colors helped because the capabilities were very different between the ports. But when the USB IF increased the number of options (and reduced the size of the connector), different colors became impossible to do.
The problem is that there are too many uses for one connector. But this is wha we wanted - a reduced number of standardized connector/power options.
… and a M1 MacBook will source 5V/3A all day long to a non-PD negotiated sink. Somewhere between the M1 and M3 Apple decided to buy into USB-IF compliance and limit to 500mA.
Has lead to some very embarrassing “works on my computer” situations on prototype boards shared with my EE colleagues (I’m a software guy who dabbles in hardware when I need to)
This quagmire (along with the version names) is why I call it the Unintuitive Serial Bus.
The lack of clarity is in keeping with the USB C connector itself, which may supply or accept power at various rates or not at all, may be fast or slow, may provide or accept video or not, and may even provide an interpretation of PCI Express but probably doesn't.
It gets even worse.
I now have two cheap Chinese gadgets (a checki printer and a tire inflater) that have USB-C ports for charging, but will only charge with the wire that came with the gadget. The other end of which is an old-style USB plug.
It seems that USB-C sockets are cheap enough parts to use them for everything, even if the manufacturer isn't going to put any actual USB circuitry behind them.
Edit: Three. I forgot about my wife's illuminated makeup mirror.
I keep a few of these around to deal with this: https://www.adafruit.com/product/6323
Very annoying though! The devices are just missing a couple resistors which is probably less than a cent on the BOM.
USB is just a complete mess. I don't mind so much ports having different capabilities if they are well documented in the specification sheets of the hardware because then at least I can find out what they are capable of, but alas it never seems to be the case. Its very hard to work out whether a port can do Displayport and to what extent/performance or its true power capability or just its real data transfer speed. More often than I like I have just hoped that something works. Anything above 5W charging and 5gbps transfer is optional.
USB is just a complete mess.
You have to go out of your way to make Apple's Lightning connector look sensible, but somehow the USB consortium has managed to do it.
Going by Fabien Sanglard's cheat sheet (who I trust uncritically) https://fabiensanglard.net/usbcheat/index.html it looks like 3.2 actually is a broader term than expected. Maybe there was some awful attempt at backwards compatibility? Or forwards?
Great site, thanks for the link. But holy heck, that "Also Known As" column is complete chaos. What the heck is wrong with the USB Consortium, do they have brain damage?
Also, according to that table, "USB4 Gen 2×2" is a downgrade on "USB 3.2 Gen 2x2", since the cable length is 0.8m instead of 1m for the same speeds. Which is uhh unexpected.
The cable length is only for the spec. You can get longer cables that achieve the higher bandwidth, they're just not certified for that.
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To be fair they seem to have taken this often-stated criticism on board. USB 4's naming is more sensible, and they've pushed the simple data speed & power labelling that makes it easier to work out what you need.
Yeah, now it's USB4 Version 2.0 / USB 80Gbps / USB4 Gen4.
According to wikipedia the current marketing names for USB are just their speed: USB 5/10/20/40/80 Gbps. No version numbers or anything else.
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I don't think they've taken the criticism on board, USB 3 still has the completely nonsensical names
The modern usb naming is to just list the speed or power output of the port.
Rather than some absurd version number it’s now just “USB 20 Gbits”
I predict in future when our civilization will advance to higher level, this phenomenon will happen with english words and jargons. e.g. here are versioned and namespaced words. topology.bio.23, topology.math.45 etc.
Welcome to the brave new world we will enter in far future.
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It means that if I pick up a random USB cable and plug it into a USB port I have no idea how well it will work or even if it will work at all. It's like the U in USB stands for Unpredictable.
Get a certified cable if it matters to you. If you pick a random cable out of the cable box it’s probably a 2.0 charging only cable that hasn’t been certified by USB IF.
Ultimately the majority of people only use usb cables for charging or 2.0 speeds for their keyboard or mic so this isn’t a problem. And for those who it is a problem, they know which one their high speed cable is.
Now I only buy USB cables if they are marked with their speed and wattage. If it’s not marked, I have to assume it carries little power and is glacially slow, which is fine to charge some Bluetooth headphones but is not usable to connect an SSD.
https://www.usb.org/sites/default/files/usb_type-c_cable_log...
You'll notice a difference between USB 3.1 and 3.2 2x2?
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This article we are discussing this about gives a great example of why understanding the difference matters a lot when purchasing hardware.
A sense of perfect knowledge of the things around you, and not feeling like someone is trying to take advantage of you any time you go shopping.
Well it means I have no idea what TFA is talking about when it mentions USB versions, for one.
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