USB Cheat Sheet (2022)

Posted by gwerbret 5 hours ago

USB Cheat Sheet (2022)(fabiensanglard.net)

191 points | 47 comments

DHowett 4 hours ago|

Excellent article.

If I could offer one correction, it would be that SBU (as specified by the USB 3.0 Promoter Group[1]) means "Sideband Use" rather than "Secondary Bus".

On some devices, it is used to carry UART; on others, audio.

[1]: https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%... (pdf)

altairprime 2 hours ago|

Their email address is under the Contact link in the header :)

1a527dd5 3 hours ago||

Tangent: Author has this fabulous post I'd highly recommend: https://fabiensanglard.net/mjolnir/index.html

I read it once years ago and I come back to it every now and then wishing my current PC (10+ years and going) would gently die so I could finally build something small and tiny.

fabiensanglard 3 hours ago|

You know, accidents happen. If you were to trip over the carpet and that venerable PC falls in the dumpster.

floxy 2 hours ago||

I don't know what short-distance data communications will be like in 2050, but we know it will be called USB.

jasongill 2 hours ago|

USB-G 4.6 SuperSpeed Plus, but the cables will still just be used for charging your random electronics and won't even work for that half the time.

Neywiny 4 hours ago||

I actually like the 3.2 naming. Gen is speed, "by" is width. It puts it very roughly on par with PCIe's naming which nobody complains about. I just don't like that USB 3, USB 3.1, and USB 3.2 are the same things. And that sales people don't seem to understand that saying a chip supports 3.1 or 3.2 tells me it's anywhere from 5-20gbps which isn't ideal.

mistyvales 4 hours ago||

PCI-E has had the same standard since its inception: 1.0, 2.0, 3.0, etc. USB has changed multiple times and has remained confusing for the vast majority of people. What was 3.0 is now not 3.0. Even 3.1 has changed. There is no reason to use this naming convention they currently have but for some reason they stick with it..

kimixa 3 hours ago|||

PCIe also had things like "1.1", "2.1" and "3.1" - that fixed issues and added functionality - but there wasn't the same crossover between "feature sets and spec revisions" and "speeds" we see in USB today.

mistyvales 3 hours ago||

Manufacturers of mainstream consumer motherboards never used 1.1, 2.1, etc. for PCI-E though. What is 4.0 on the spec sheet will be 4.0 to the buyer. My old 2016 motherboard has a slew of 3.0 labelled USB ports that are now not 3.0, hence the conundrum. It just doesn't make sense why they changed established naming conventions. Is this something that causes me sleepless nights? Not in the least. But it's still an annoyance for consumers and even advanced users as detailed in that latest Geerling video et al.

Neywiny 3 hours ago|||

Possibly they stick with it because it's usable (ish) and it was driving everyone up the wall when they'd change it?

retired 3 hours ago||

And not only the sales people. Windows doesn't report anywhere what your motherboard is capable of, and even if you connect with a device it will not tell you the speed it agreed on.

15155 4 hours ago||

Good sheet. Worth adding:

- Female vs male crossover naming and pinouts for Type-C connectors

- Actual voltage, modulation and signaling schemes (USB4v2 uses PAM3 11b/7t encoding)

- PD generations and profiles

mschuster91 4 hours ago|

... and the bunch of proprietary voltage schemes like Quickcharge.

retired 3 hours ago||

Thanks to the EU those are now forbidden, all phones and laptops should be compatible with USB-PD.

Update: USB-PD is a requirement, but manufacturers are allowed to have their own proprietary charging solution.

dang 2 hours ago||

Related. Others?

USB Cheat Sheet - https://news.ycombinator.com/item?id=31271038 - May 2022 (168 comments)

userbinator 3 hours ago||

IMHO USB 3.0 was the last sanely-named version. Then again, if you're familiar with Ethernet, the proliferation of variants isn't unexpected.

maxloh 4 hours ago||

I once heard that the USB naming is misleading by design so that vendors could still sell older generations accessories they had in stock. The USB-IF just rebrands the old ones to make them sound current.

Imagine the following naming:

  USB 3.0 / USB 3.1 Gen 1 / USB 3.2 Gen 1 -> USB 3 5Gbps
  USB 3.1 / USB 3.1 Gen 2 / USB 3.2 Gen 2 -> USB 3 10Gbps
  USB 3.2 Gen 2x2 -> USB 3 20Gbps

Isn't that much clearer? I think USB 4 is finally going to the right direction.

QuantumNomad_ 24 minutes ago||

I have a USB hub that I bought recently, that has very nice markings on it that are almost like you say :)

I connects via USB4 to the host, and has the following markings on its ports:

- Power in/USB 10Gbps

- USB 10Gbps

- 8K HDMI

Pretty happy with this one so far.

sgjohnson 3 hours ago|||

> I think USB 4 is finally going to the right direction.

USB 4 is actually going into an even worse direction. USB 4 = Thunderbolt 4, except everything is optional. e.g. USB 4 might not even support DP Alt mode. Thunderbolt 4 always will.

brigade 2 hours ago||

Even backwards compatibility is optional in USB4. There are USB4 devices (SSDs at least) that will not function when connected to USB 3 ports.

kubik369 3 hours ago|||

I think this practice is rather blatantly what you say. The same thing with HDMI forum folding HDMI 2.0 into HDMI 2.1. They made the new 2.1 features optional, therefore manufacturers were able to call their 2.0 devices 2.1 without actually supporting the 2.1 features. AMD has been recently doing similar things, releasing “new” generation of mobile processors where half of them are just rebrands of the older generation.

xzjis 3 hours ago||

Or it could be: 5 Gbps --> USB 3 10 Gbps --> USB 3.1 20 Gbps --> USB 3.2

Higher number = better

drob518 3 hours ago||

I’ve been a tech guy for 45 years and I still can’t figure out USB and Thunderbolt and what goes with what and how fast it’s supposed to run.

15155 3 hours ago||

If you buy Thunderbolt 5 cables: every USB standard is compatible and then some.

ProllyInfamous 3 hours ago||

It wasn't until last year that I finally purchased my first USB-C device/cables – and after years of solid DisplayPort and Thunderbolt2 connections I absolutely hate USB-C (it's too delicate, physically).

Not until 2023 did I even have a computer newer than 2012, so I missed almost all of USB3's hayday — including nomenclature disputes — but the speeds sure are an improvement!

pxeboot 3 hours ago|

I still don't understand why MacBooks support USB4/Thunderbolt 4/5, but NOT USB 3.2 Gen 2x2. So you can get 20-40Gb/s speeds with more expensive external disks, but only 10Gb/s with the cheaper, more commonly available ones that advertise 20Gb/s.

altairprime 2 hours ago|

I believe it’s that MacBooks support Thunderbolt primarily and USB only where absolutely necessary beyond what’s coded into one of the TB specs; and I assume TB doesn’t define 3.2x2x2 as part of any TB spec <=5?

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