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USB Cheat Sheet

371 points by WithinReason 4y ago

0xTJ 4y ago
Just how much do you have to hate consumers to come up with a scheme like this? Increment revisions as you add more features, add something to the end to say how fast it goes. The 3.2 renaming is idiotic.
netsharc 4y ago
Ah USB. In the old days it was different cables for different things, nowadays it's 1 connector for everything but beware, the cable might physically plug into the socket, but whether you'll get the functionality you want?
- doubled112 4y ago
  Seems it is going backward to me too. At one point I remember hooking up a computer being like one of those shape puzzles we give children. If you can match them they'll work. No two of my devices used the same cable or port, but if it fit it'd work. Keyboard switched to PS/2 so those and PS/2 mice were confusing, but eventually they standardized on colours. USB came out and you could just plug it in wherever. This was great. And now? 20 combinations of cable features with the same socket but all do something else. I can only imagine what the return rate will be for stuff like this.
- izacus 4y ago
  Just how many devices do you meet that regularly hit those edge cases? Outside 4K+ multimonitor connections? (It's really popular and easy to bash on USB on this forum, but it turns out that in real life your USB-C device will "just work" for pretty much all setups outside really fringe high performance ones. And even those will usually just negotiate lower rate.)
a3w 4y ago
USB 4 (opt) is ... optical? Or optional?
- willis936 4y ago
  It would have a longer max length if the data lanes were optical.
  - johnwalkr 4y ago
    You can actually get optical usb3 and thunderbolt (all generations) cables. Thunderbolt was originally called light peak and shown off by Intel and Apple in demos as optical, and Sony had a line of laptops with optical light peak connectors to connect to external GPUs. But ultimately the default became non-optical because it can carry power too.
    - mschuster91 4y ago
      > But ultimately the default became non-optical because it can carry power too. There's no problem in making a cable with two fibre leads for data and two (at higher lengths thicker to reduce issues with voltage drop) power lines.
      - johnwalkr 4y ago
        That’s a good point although optical usb3 and thunderbolt3 cables tend to be advertised with electrical isolation as a feature and suggest using an external hub to provide power.[1] [1] https://www.corning.com/optical-cables-by-corning/worldwide/en/products/usb-optical-cables.html https://www.corning.com/optical-cables-by-corning/worldwide/...
        mschuster91 4y ago
        Whoa, that pricing is quite a bit.
        johnwalkr 4y ago
        Yeah that must be the real reason it didn’t catch on as a default. Light peak did have cheaper cables though, the optical part was in the connector, not the cable. The connector was a usb-a connector if I remember correctly.. and the history is actually pretty interesting! Apparently that connector was deemed proprietary and frowned upon by the usb folks for causing consumer confusion[1]. Kind of hilarious now, seeing how thunderbolt 1/2 ended up barely being adopted outside of Apple and usb itself is a confusing mess these days. [1] https://www.theverge.com/2011/10/14/2490694/how-sony-accidentally-did-the-right-thing-with-light-peak https://www.theverge.com/2011/10/14/2490694/how-sony-acciden...
kashunstva 4y ago
> May 05, 2025 The article is dated May 5, 2025. I've long been wondering about the future of USB.
- Beta-7 4y ago
  USB 4.2 (later renamed to USB 3.2 gen 2 Mk. 1) comes with built in time traveling. They just keep adding features to the protocol and making it complicated.
- vesinisa 4y ago
  OP forgot [2025] from the title.
  - WithinReason 4y ago
    I could still fix it, but I fear the wrath of Dang
- notorandit 4y ago
  Not to be read before: see article time stamp
- Fatnino 4y ago
  It's a form of SEO. Google promotes "fresh" content, so if it sees a date less than a year ago it often assumes the content is better. Normally you will see this abused by crappy content mills using a plugin that constantly updates the date on their garbage. Putting a static date from 3 years in the future seems like a quick a dirty hack to do the same thing.
willis936 4y ago
USB 4 AKA USB 4 Gen2x2 USB 4 (opt) AKA USB 4 Gen3x2 They had a chance to fix their colossal fuckup and they decided not to.
- ThreePinkApples 4y ago
  In marketing and on cables they've chosen to use the terms USB4 20Gbps and USB4 40Gbps, so at least that's explicit. There's also officials ways to mark cables as being 100W or 240W capable.
- nolok 4y ago
  Their issue was not the naming for consumer or tech user, their issue was "how do we allow any random laptop from claiming latest usb despite not actually supporting it". It was super obvious with usb 3 and its sub versions, and it gets even worse with 4.
  - paulmd 4y ago
    Yes. The "IF" in "USB-IF" stands for implementers forum, it is a consortium of hardware companies who make devices. It's preferable to them if they can slap "USB 3.2 support!" on the box without having to redo their boards with a new, expensive component. In other words, the incentives here are for USB-IF to promote customer confusion, not to reduce it, because that confusion can sell devices and push profit margins. It's absolutely terrible that the EU is giving this group a legal monopoly on the ability to create and proliferate new standards. Their incentives fundamentally run against the consumer and they have repeatedly acted against the interests of the consumer. Unlike HDMI, there is no VESA to counterbalance them, it is USB or nothing, so you'll have to deal with these crappy standards going forward. -- HDMI is doing something similar now too - "HDMI 2.1" is a completely hollow standard where every single feature and signaling mode added since HDMI 2.0 is completely optional. You can take HDMI 2.0 hardware and get it recertified as HDMI 2.1 without any changes - actually you must do this since HDMI Forum is not issuing HDMI 2.0 certifications any more, only HDMI 2.1 going forward, the new standard "supercedes" the old one entirely. So - "HDMI 2.1" on the box doesn't mean 4K120 support, it doesn't mean VRR support, it doesn't mean HDR support. It could actually just literally be HDMI 2.0 hardware inside. You need to look for specific feature keywords if that is your goal. https://arstechnica.com/gadgets/2021/12/the-hdmi-forum-follows-the-usb-if-in-using-new-version-numbers-to-refer-to-old-ports/ https://arstechnica.com/gadgets/2021/12/the-hdmi-forum-follo... https://www.youtube.com/watch?v=qo9Y7AMPn00 https://www.youtube.com/watch?v=qo9Y7AMPn00
hdjjhhvvhga 4y ago
If you think it's not complicated enough, add Thunderbolt to it.
- CharlesW 4y ago
  Thunderbolt 4 is effectively USB 4. https://www.cablematters.com/blog/Thunderbolt/usb4-vs-thunderbolt-3 https://www.cablematters.com/blog/Thunderbolt/usb4-vs-thunde...
legalcorrection 4y ago
Suggestion: maybe include all the USB-C-plug Thunderbolt versions too. My personal policy these days is to just buy reputable Thunderbolt cables for all my USB-C needs. Maybe I'm doing the wrong thing? Also, I think there's a difference between active and passive USB-C cables, or something like that.
- masklinn 4y ago
  > Maybe I'm doing the wrong thing? If you're happy with it then probably not. The main possible issues are that it's more expensive and you get shorter and thicker (less flexible) cables, a passive non-optical TB (or USB4) cable will top out around 1m. Less capable cables can be longer and thinner which is convenient for e.g. mice and such small devices. But otherwise may not matter overly much.
  - moron4hire 4y ago
    I've been pretty happy with my less flexible cables. I don't need to snake them around tight corners anywhere. Being less flexible seems to keep them from auto-tangling.
masklinn 4y ago
Some of the entries seem incorrect: "USB 3.2 (USB 3.2 Gen 2x2) and "USB 4" (USB 4 USB4 Gen 2×2) should have the same nominal data rate of 2500MB/s, they're 2 lanes (x2) of 10GB/s. Though they are apparently coded differently electrically, so they're distinct protocols. The tables would benefit from mentioning the coding (8/10 or 128/132) as IMO it's one of the most confusing bits when you see the effective data rates: * USB 3.2 Gen 1x2 has a nominal data rate of 10G (2 lanes at 5G) with a raw throughput of 1GB/s (effective data rates topping out around 900MB/s) * USB 3.2 Gen 2x1 has the same nominal data rate of 10G (1 lane at 10G) but a raw throughput of 1.2GB/s (and effective data rates topping out around 1.1GB/s) The difference is that Gen 1x uses the "legacy" 8/10 encoding, while Gen 2x uses the newer 128/132 encoding, and thus has a much lower overhead (around 3%, versus 20).
- deleted 4y ago
  [deleted]
- CamperBob2 4y ago
  He goes off the rails earlier than that, by saying that USB 2.0 is "also known as" Hi-speed. HS is only one data rate supported by the USB 2.0 standard; it incorporates both full speed from the earlier standard and low speed, which isn't mentioned at all.
  - masklinn 4y ago
    That's more of an approximation matching how, frankly, most people think of the specs: yes USB 2.0 supersedes 1.1 entirely, but everyone will think of "full speed" and "low speed" as USB 1 which are BC supported by USB 2.0. That's also why USB 3.1 and 3.2's rebranding of previous versions is so confusing and a pain in the ass to keep straight: USB 3.2 1x1 is USB 3.1 Gen 1 is USB 3.0 (ignoring the USB 2.0 BC).
  - dwaite 4y ago
    Right, per his chart "Full Speed" should be known as USB 1.1 Full Speed and USB 2.0 Full Speed.
- belter 4y ago
eugene3306 4y ago
just curious. Can USB3 work without D+ and D- ?
- deleted 4y ago
  [deleted]
- formerly_proven 4y ago
  USB 3 and previous standards are completely separate connections and software stacks - the USB 1/2 D+/D- pair does not interact at all with SSRX/SSTX. You should be able to literally cut the D+/D- wires in an USB 3 cable and it should still work as a USB 3 cable.
  - kevin_thibedeau 4y ago
    I doubt any normal hosts will enumerate a USB device without the USB 2 data lines. PD will definitely not work. You might be able to get an alt mode running.
    - cesarb 4y ago
      They probably would enumerate just fine, because the SuperSpeed enumeration is completely independent from the USB 2.x enumeration. USB-PD uses a separate pin/wire, not the USB 2.x D-/D+ pair, and you cannot get an alt mode running (except the special analog audio and debug accessory modes) if USB-PD doesn't work, since alt mode enumeration goes on top of USB-PD.
      - Aachen 4y ago
        I'd actually be interested in a 3-only cable. Force it to use high speed or bust, no surprises, no guessing at which proto runs under the hood on that "universal" connector. Didn't know it was possible; I might make one once I've got a spare cable (just today I've got another spare but they always have just 4 cables). More for geeky/testing purposes than to replace all my cables, but still
Kab1r 4y ago
USB versioning is such a clusterfuck.
- 411111111111111 4y ago
  There was a really short timeframe when I was really positive about USB, but that has been long lost since. They should've never allowed cables to only provide some capabilities and still get the branding. Having capabilities for connectors was fine imo, but also accepting them with cables was bad because you cannot really find out what it supports and where the issue originates of something goes wrong
  - jsjohnst 4y ago
    It’s why I always buy TB3 (or now TB4) cables rather than a cheaper USB-C to USB-C. Due to the strict requirements on TB cables, you can pretty much guarantee it’ll support any use case (alt modes, PD, etc). Sometimes overspending is worth the headache prevention.
    - jbverschoor 4y ago
      Apple just released a €159 cable
      - jsjohnst 4y ago
        And? Apple used to sell a way more expensive than that TB2 cable if high price is your point and besides, saying Apple charges a premium price for a premium product (like this) is about as insightful as saying the sky is blue.
      - CharlesW 4y ago
        FWIW, Monoprice's 1m USB4/TB4 cable (100W) is $25. https://www.monoprice.com/product?p_id=41946 https://www.monoprice.com/product?p_id=41946
        4y ago
dschuetz 4y ago
So where exactly does USB-C fall into? I have 2 different generations of USB-C hosts, and they behave quite differently when approaching max cap, especially with high-quality low-latency audio (USB-C was supposed to be de-facto replacement for FireWire).
- hyperman1 4y ago
  It's orthogonal. Usb A is a host side connection Usb B (normal/mini/micro) is a client side connector Usb C is a 2 way connector. Each of them can be implemented for each USB version, except USB C came later and makes no sense befor USB 3. Then USB versions added features, signalling conventions and wires. But the USB A and B connector are backward compatible all the way to USB 1.0 1.5Mbit/s
  - kevin_thibedeau 4y ago
    On-the-Go allows mini and micro B to be host as well.
- LeonidasXIV 4y ago
  USB-C is a connector type, like USB-A (usually known as the classic USB plug) and USB-B (usually the other side of said plug, a square kind of connector). USB-B had other offspring like miniUSB and microUSB (note that in these cases on the other side of the cable you usually have a USB-A plug). USB-C is the first time cables have the same connector on both sides, so it obsoletes USB-A and USB-B. But what is sent over USB-C? Can be USB 3 with which it is often conflated because they came around the same time, but it can also be USB 2, so it is a bit hard to tell. But USB 3 can use old style USB-A as well (the blue plugs with the same shape as the classic USB plugs) and USB-C (the microUSB plugs with an extension off to the side).
  - microtonal 4y ago
    Can be USB 3 [...] USB 2, so it is a bit hard to tell. ...or Thunderbolt, USB 4, DisplayPort (through Alt-mode or encapsulated in Thunderbolt), or HDMI (Alt-mode), or MHL (Alt-mode), USB Power Delivery... Unfortunately, not every cable with USB-C connectors can carry all of these. E.g. there are USB-C cables that can only carry USB 2. Or cables that can carry USB 3, but not Thunderbolt. Also, not all cables can carry the same wattage for power delivery. It's a mess.
can16358p 4y ago
So on the next versions of USB, the cable length will get shorter and shorter until the max gets to 5cm? While I get the technical reasoning about high frequency/attenuation etc that limits cable length as speeds go higher, there are obviously some practical limits to how short cables can be. How would that be solved, I don't know.
- CoastalCoder 4y ago
  Not my area of expertise, but maybe some (unrealistic) options include using fiber optics for the data lines, or adding more data lines.
  - birktj 4y ago
    There already exists some fiber-optic USB cables that come in lengths >50m and with support for USB 3.1 so it doesn't seem like a very unrealistic option.
    - Chilinot 4y ago
      That sounds more like fiber optic adapters/converters that fit into usb-ports and talk usb, rather than USB-cables that can be 50+ meters.
      - jayd16 4y ago
        Seems like you can get 3m optical usb-c cables. Oculus sells an official "Full featured USB active optical cable. USB 3.2 Gen 1 Type-C" for tethered play. That's what the cheatsheet says so maybe that's part of the spec.
      - jsjohnst 4y ago
        I think GP is thinking of fiber optic Thunderbolt cables probably.
      - duskwuff 4y ago
        Some USB4 / Thunderbolt cables are like that, but with copper in the middle. The drivers on the device end wouldn't be able to maintain signal integrity over that size of cable, so there's a pair of transceivers in each end of the cable to convert the signal into a format that'll survive transmission.
_joel 4y ago
I've definitely used 5m+ extensions on USB1 (and 2 iirc) before. I guess it'd be sketchy running something that requires decent throughput and not b0rk on ECC/FEC/whatever it uses but for temperature sensors which I was using, it was fine.
- TonyTrapp 4y ago
  A long time ago, I was using a USB 1 or 2 Wifi adapter through a USB extension cord, I'm pretty sure the total cable length was more than 5 meters. It "worked", but even just flicking a light switch caused the network connection to reset. So yeah, it may "work", for certain values of "work".
gsich 4y ago
CC1 and CC2 pins are missing.
- megous 4y ago
  They are not required to be wired through all cables. Similar to SBU signals.
Tepix 4y ago
I have a related question: Is the official name USB 3.2 Gen 2x2 or USB 3.2 Gen 2×2 (x vs ×)?
- masklinn 4y ago
  The USB pages and specs (on usb.org) seem to use "x" where they use the technical spelling.
- jjoonathan 4y ago
  Which USB do I choose for a 4x4 offroad adventure?
Villodre 4y ago
I'm always flabbergasted at how difficult and hostile to the user is discern between the various USB standards.
Someone 4y ago
No USB On-The-Go (https://en.wikipedia.org/wiki/USB_On-The-Go https://en.wikipedia.org/wiki/USB_On-The-Go) or Wireless USB (https://en.wikipedia.org/wiki/Wireless_USB https://en.wikipedia.org/wiki/Wireless_USB)? USB is a triumph of marketeers over engineers. All these things are called USB because USB sells (see also: Bluetooth).
- ChrisRR 4y ago
  Bluetooth Smart aka. Bluetooth Low Energy aka. Wibree aka. not actually bluetooth
- IshKebab 4y ago
  I don't know anything about wireless USB but USB OTG is called USB because it is USB. It's not some totally unrelated protocol.
  - jandrese 4y ago
    I thought OTG was just changing up where the host controller is sitting in the USB relationship? So you can have a device that acts like a client when hooked to a computer, or a master when hooked to a thumb drive/webcam/etc...?
    - IshKebab 4y ago
      Yeah it just allows you to use a B port as a host (if supported). It's still the USB protocol.
      - cesarb 4y ago
        AFAIK, according to the standard you still cannot use the B port as a host, it should instead be an AB port (a socket in which both A and B plugs fit).
        thatfunkymunki 4y ago
        i cannot find any examples of this kind of port, can you share a link?
Lucasoato 4y ago
Why didn't they focus enough on cable length? I'm not sure about how much latency they would add since the current is still traveling at light speed. Maybe there's someone in the world wondering if it's possible to emulate MarioKart from his office PC to the living room with a 10m HDMI and USB3 cable... Just guessing :)
stavros 4y ago
What does the U in USB stand for again?
- theandrewbailey 4y ago
  Unintuitive.
- _joel 4y ago
  Unintelligable
- notorandit 4y ago
  Uikipedia
- jbverschoor 4y ago
  U-turn
- jbverschoor 4y ago
  Actually, I think it’s just a upside down “∩”. Makes sense because the non-C connectors are always upside down, and all it does is intersect wires.
synergy20 4y ago
Like the simple site design with a one page info about USB. someone please make similar one-page with tables about PCI Express, Ethernet, HDMI...
- NoXero 4y ago
  I second that request!
- ProZsolt 4y ago
  I created a cheat sheet for Ethernet, when I built my home network: https://github.com/ProZsolt/runbook/blob/master/ethernet-cable.md https://github.com/ProZsolt/runbook/blob/master/ethernet-cab...
  - navaati 4y ago
    Really nice ! Today I learn that there is a 25 and 40G-BASE-T on copper, these PHY must heat like hell haha.
  - synergy20 4y ago
    shoud 100, 400, 800G be added, yes a bit earlier for 800G but I think 100/400G are already in use at data centers.
    - ProZsolt 4y ago
      This only covers twisted pair, as I only use this as reference when I need new endpoints in my or my parents house. I'll update the guide when I rewire my house with fiber optics (currently I don't even use the full potential of cat 6), but contributions are welcomed.
markus_zhang 4y ago
Is that year 2025...
- a3w 4y ago
  Nope, USB4 has been defined for a while now.
cosmotic 4y ago
Where's the standard speed?
IvanK_net 4y ago
Fun fact: USB 2.0 webcams have been existing for over 10 years. USB 2.0 is 60 MB/s. A pixel of an image is 3 Bytes. A 1920x1080 FullHD image is 6.2 MB. At 30 frames per second, second of a FullHD video is 186 MB. How did they do that? Answer: frames are transferred as JPEG files. Even a cheap $15 webcam is a tiny computer (with a CPU, RAM, etc), which runs a JPEG encoder program.
- kevin_thibedeau 4y ago
  The cheap ones are using hardware JPEG encoders. The associated micro isn't powerful enough to do it in firmware alone.
  - masklinn 4y ago
    Surprised they don't use a hardware video encoder, is it because the well and efficiently supported formats are all MPEG, and thus have fairly high licensing cost on top of the hardware? Or because even efficient HVEs use more resources than webcams can afford? Or because inter-frame coding requires more storage, which (again) means higher costs, which (again) eats into the margin, which cheap webcam manufacturers consider not worth the investment?
    - martinmunk 4y ago
      My older Logitech C920 has an on-board H.264 encoder. Newer revisions of the same model does not. I haven't figured out why they chose to remove it, but your point about licensing cost combined with them not advertising it much as a feature, and most of their competitors not including "proper" video encoding might explain it. Edit: Found an official explanation here: https://www.logitech.com/en-us/video-collaboration/resources/think-tank/articles/article-logitech-and-h264-encoding.html https://www.logitech.com/en-us/video-collaboration/resources... TLDR, they figure most computers at that point had HW encoders.
      - lxgr 4y ago
        Unfortunately, this makes it much harder to use these as webcams on a Raspberry Pi (which even has H.264 hardware acceleration – the bottleneck is decoding the MJPEG stream from the camera, for which ffmpeg does not have hardware acceleration on the RPi).
moffkalast 4y ago
All it's missing is the pinouts and the charger resistor divider setup definitions.
Aragorn2331 4y ago
Hello Fabien ! I saw on twitter that you had built a gaming setup, can you write an article on your blog as you did for your silent pc ?
- fabiensanglard 4y ago
  I did build a PC last year especially to play Diablo2: Ressurected. I did write something at the time but never published it. Maybe I will clean it up.
- fabiensanglard 4y ago
  Here it is https://fabiensanglard.net/d2r/index.html https://fabiensanglard.net/d2r/index.html
  - Aragorn2331 4y ago
    Amazing setup for amazing game ! Thanks for this post, i love to read you :-)
IshKebab 4y ago
This is wrong. For example Full Speed isn't a name for USB 1, it's the name for a speed which is supported by USB 1 and 2 (not sure about 3). Most USB microcontrollers are Full Speed USB 2.
JoeDaDude 4y ago
If only it included a guide to the different USB connectors, but that might make TFA too long to publish.
cesaref 4y ago
There's something about the naming of USB that is great. I love how there are now something like a dozen 'universal' standards, and how the serial bus now has multiple lanes.
dimman 4y ago
Thanks. Nit-picking here but ground is usually abbreviated GND, not GRD.
datastack 4y ago
Hi, nice cheatsheet! I've published it on DataStack, where anyone can contribute improvements (like adding columns or corrections). https://datastack.net/datastack/usb https://datastack.net/datastack/usb I can transfer the project to you if you like.
joshspankit 4y ago
If you don’t mind sharing: what was the “bug”?
PowerBar 4y ago
In the "USB-A/B" section, they're all labelled "Type-A", the 3rd and 4th should be labelled "Type B". It's also missing - mini-b 4 wire (older phones, etc) - micro-b 4 wire (most electronics prior to type c) - micro-b 8 wire (mostly seen only found on external 2.5" HDDs) There were also a bunch of other connectors (mini-a, mini-a/b, etc) but they are very rare.

371 points by WithinReason 4y ago

0xTJ 4y ago

Just how much do you have to hate consumers to come up with a scheme like this? Increment revisions as you add more features, add something to the end to say how fast it goes. The 3.2 renaming is idiotic.

netsharc 4y ago

Ah USB. In the old days it was different cables for different things, nowadays it's 1 connector for everything but beware, the cable might physically plug into the socket, but whether you'll get the functionality you want?

doubled112 4y ago
Seems it is going backward to me too. At one point I remember hooking up a computer being like one of those shape puzzles we give children. If you can match them they'll work. No two of my devices used the same cable or port, but if it fit it'd work. Keyboard switched to PS/2 so those and PS/2 mice were confusing, but eventually they standardized on colours. USB came out and you could just plug it in wherever. This was great. And now? 20 combinations of cable features with the same socket but all do something else. I can only imagine what the return rate will be for stuff like this.
izacus 4y ago
Just how many devices do you meet that regularly hit those edge cases? Outside 4K+ multimonitor connections? (It's really popular and easy to bash on USB on this forum, but it turns out that in real life your USB-C device will "just work" for pretty much all setups outside really fringe high performance ones. And even those will usually just negotiate lower rate.)

a3w 4y ago

USB 4 (opt) is ... optical? Or optional?

willis936 4y ago
It would have a longer max length if the data lanes were optical.
- johnwalkr 4y ago
  You can actually get optical usb3 and thunderbolt (all generations) cables. Thunderbolt was originally called light peak and shown off by Intel and Apple in demos as optical, and Sony had a line of laptops with optical light peak connectors to connect to external GPUs. But ultimately the default became non-optical because it can carry power too.
  - mschuster91 4y ago
    > But ultimately the default became non-optical because it can carry power too. There's no problem in making a cable with two fibre leads for data and two (at higher lengths thicker to reduce issues with voltage drop) power lines.
    - johnwalkr 4y ago
      That’s a good point although optical usb3 and thunderbolt3 cables tend to be advertised with electrical isolation as a feature and suggest using an external hub to provide power.[1] [1] https://www.corning.com/optical-cables-by-corning/worldwide/en/products/usb-optical-cables.html https://www.corning.com/optical-cables-by-corning/worldwide/...
      - mschuster91 4y ago
        Whoa, that pricing is quite a bit.
        johnwalkr 4y ago
        Yeah that must be the real reason it didn’t catch on as a default. Light peak did have cheaper cables though, the optical part was in the connector, not the cable. The connector was a usb-a connector if I remember correctly.. and the history is actually pretty interesting! Apparently that connector was deemed proprietary and frowned upon by the usb folks for causing consumer confusion[1]. Kind of hilarious now, seeing how thunderbolt 1/2 ended up barely being adopted outside of Apple and usb itself is a confusing mess these days. [1] https://www.theverge.com/2011/10/14/2490694/how-sony-accidentally-did-the-right-thing-with-light-peak https://www.theverge.com/2011/10/14/2490694/how-sony-acciden...

kashunstva 4y ago

> May 05, 2025 The article is dated May 5, 2025. I've long been wondering about the future of USB.

Beta-7 4y ago
USB 4.2 (later renamed to USB 3.2 gen 2 Mk. 1) comes with built in time traveling. They just keep adding features to the protocol and making it complicated.
vesinisa 4y ago
OP forgot [2025] from the title.
- WithinReason 4y ago
  I could still fix it, but I fear the wrath of Dang
notorandit 4y ago
Not to be read before: see article time stamp
Fatnino 4y ago
It's a form of SEO. Google promotes "fresh" content, so if it sees a date less than a year ago it often assumes the content is better. Normally you will see this abused by crappy content mills using a plugin that constantly updates the date on their garbage. Putting a static date from 3 years in the future seems like a quick a dirty hack to do the same thing.

willis936 4y ago

USB 4 AKA USB 4 Gen2x2 USB 4 (opt) AKA USB 4 Gen3x2 They had a chance to fix their colossal fuckup and they decided not to.

ThreePinkApples 4y ago
In marketing and on cables they've chosen to use the terms USB4 20Gbps and USB4 40Gbps, so at least that's explicit. There's also officials ways to mark cables as being 100W or 240W capable.
nolok 4y ago
Their issue was not the naming for consumer or tech user, their issue was "how do we allow any random laptop from claiming latest usb despite not actually supporting it". It was super obvious with usb 3 and its sub versions, and it gets even worse with 4.
- paulmd 4y ago
  Yes. The "IF" in "USB-IF" stands for implementers forum, it is a consortium of hardware companies who make devices. It's preferable to them if they can slap "USB 3.2 support!" on the box without having to redo their boards with a new, expensive component. In other words, the incentives here are for USB-IF to promote customer confusion, not to reduce it, because that confusion can sell devices and push profit margins. It's absolutely terrible that the EU is giving this group a legal monopoly on the ability to create and proliferate new standards. Their incentives fundamentally run against the consumer and they have repeatedly acted against the interests of the consumer. Unlike HDMI, there is no VESA to counterbalance them, it is USB or nothing, so you'll have to deal with these crappy standards going forward. -- HDMI is doing something similar now too - "HDMI 2.1" is a completely hollow standard where every single feature and signaling mode added since HDMI 2.0 is completely optional. You can take HDMI 2.0 hardware and get it recertified as HDMI 2.1 without any changes - actually you must do this since HDMI Forum is not issuing HDMI 2.0 certifications any more, only HDMI 2.1 going forward, the new standard "supercedes" the old one entirely. So - "HDMI 2.1" on the box doesn't mean 4K120 support, it doesn't mean VRR support, it doesn't mean HDR support. It could actually just literally be HDMI 2.0 hardware inside. You need to look for specific feature keywords if that is your goal. https://arstechnica.com/gadgets/2021/12/the-hdmi-forum-follows-the-usb-if-in-using-new-version-numbers-to-refer-to-old-ports/ https://arstechnica.com/gadgets/2021/12/the-hdmi-forum-follo... https://www.youtube.com/watch?v=qo9Y7AMPn00 https://www.youtube.com/watch?v=qo9Y7AMPn00

hdjjhhvvhga 4y ago

If you think it's not complicated enough, add Thunderbolt to it.

CharlesW 4y ago
Thunderbolt 4 is effectively USB 4. https://www.cablematters.com/blog/Thunderbolt/usb4-vs-thunderbolt-3 https://www.cablematters.com/blog/Thunderbolt/usb4-vs-thunde...

legalcorrection 4y ago

Suggestion: maybe include all the USB-C-plug Thunderbolt versions too. My personal policy these days is to just buy reputable Thunderbolt cables for all my USB-C needs. Maybe I'm doing the wrong thing? Also, I think there's a difference between active and passive USB-C cables, or something like that.

masklinn 4y ago
> Maybe I'm doing the wrong thing? If you're happy with it then probably not. The main possible issues are that it's more expensive and you get shorter and thicker (less flexible) cables, a passive non-optical TB (or USB4) cable will top out around 1m. Less capable cables can be longer and thinner which is convenient for e.g. mice and such small devices. But otherwise may not matter overly much.
- moron4hire 4y ago
  I've been pretty happy with my less flexible cables. I don't need to snake them around tight corners anywhere. Being less flexible seems to keep them from auto-tangling.

masklinn 4y ago

Some of the entries seem incorrect: "USB 3.2 (USB 3.2 Gen 2x2) and "USB 4" (USB 4 USB4 Gen 2×2) should have the same nominal data rate of 2500MB/s, they're 2 lanes (x2) of 10GB/s. Though they are apparently coded differently electrically, so they're distinct protocols. The tables would benefit from mentioning the coding (8/10 or 128/132) as IMO it's one of the most confusing bits when you see the effective data rates: * USB 3.2 Gen 1x2 has a nominal data rate of 10G (2 lanes at 5G) with a raw throughput of 1GB/s (effective data rates topping out around 900MB/s) * USB 3.2 Gen 2x1 has the same nominal data rate of 10G (1 lane at 10G) but a raw throughput of 1.2GB/s (and effective data rates topping out around 1.1GB/s) The difference is that Gen 1x uses the "legacy" 8/10 encoding, while Gen 2x uses the newer 128/132 encoding, and thus has a much lower overhead (around 3%, versus 20).

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CamperBob2 4y ago
He goes off the rails earlier than that, by saying that USB 2.0 is "also known as" Hi-speed. HS is only one data rate supported by the USB 2.0 standard; it incorporates both full speed from the earlier standard and low speed, which isn't mentioned at all.
- masklinn 4y ago
  That's more of an approximation matching how, frankly, most people think of the specs: yes USB 2.0 supersedes 1.1 entirely, but everyone will think of "full speed" and "low speed" as USB 1 which are BC supported by USB 2.0. That's also why USB 3.1 and 3.2's rebranding of previous versions is so confusing and a pain in the ass to keep straight: USB 3.2 1x1 is USB 3.1 Gen 1 is USB 3.0 (ignoring the USB 2.0 BC).
- dwaite 4y ago
  Right, per his chart "Full Speed" should be known as USB 1.1 Full Speed and USB 2.0 Full Speed.
belter 4y ago

eugene3306 4y ago

just curious. Can USB3 work without D+ and D- ?

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formerly_proven 4y ago
USB 3 and previous standards are completely separate connections and software stacks - the USB 1/2 D+/D- pair does not interact at all with SSRX/SSTX. You should be able to literally cut the D+/D- wires in an USB 3 cable and it should still work as a USB 3 cable.
- kevin_thibedeau 4y ago
  I doubt any normal hosts will enumerate a USB device without the USB 2 data lines. PD will definitely not work. You might be able to get an alt mode running.
  - cesarb 4y ago
    They probably would enumerate just fine, because the SuperSpeed enumeration is completely independent from the USB 2.x enumeration. USB-PD uses a separate pin/wire, not the USB 2.x D-/D+ pair, and you cannot get an alt mode running (except the special analog audio and debug accessory modes) if USB-PD doesn't work, since alt mode enumeration goes on top of USB-PD.
    - Aachen 4y ago
      I'd actually be interested in a 3-only cable. Force it to use high speed or bust, no surprises, no guessing at which proto runs under the hood on that "universal" connector. Didn't know it was possible; I might make one once I've got a spare cable (just today I've got another spare but they always have just 4 cables). More for geeky/testing purposes than to replace all my cables, but still

Kab1r 4y ago

USB versioning is such a clusterfuck.

411111111111111 4y ago
There was a really short timeframe when I was really positive about USB, but that has been long lost since. They should've never allowed cables to only provide some capabilities and still get the branding. Having capabilities for connectors was fine imo, but also accepting them with cables was bad because you cannot really find out what it supports and where the issue originates of something goes wrong
- jsjohnst 4y ago
  It’s why I always buy TB3 (or now TB4) cables rather than a cheaper USB-C to USB-C. Due to the strict requirements on TB cables, you can pretty much guarantee it’ll support any use case (alt modes, PD, etc). Sometimes overspending is worth the headache prevention.
  - jbverschoor 4y ago
    Apple just released a €159 cable
    - jsjohnst 4y ago
      And? Apple used to sell a way more expensive than that TB2 cable if high price is your point and besides, saying Apple charges a premium price for a premium product (like this) is about as insightful as saying the sky is blue.
    - CharlesW 4y ago
      FWIW, Monoprice's 1m USB4/TB4 cable (100W) is $25. https://www.monoprice.com/product?p_id=41946 https://www.monoprice.com/product?p_id=41946
      - 4y ago

dschuetz 4y ago

So where exactly does USB-C fall into? I have 2 different generations of USB-C hosts, and they behave quite differently when approaching max cap, especially with high-quality low-latency audio (USB-C was supposed to be de-facto replacement for FireWire).

hyperman1 4y ago
It's orthogonal. Usb A is a host side connection Usb B (normal/mini/micro) is a client side connector Usb C is a 2 way connector. Each of them can be implemented for each USB version, except USB C came later and makes no sense befor USB 3. Then USB versions added features, signalling conventions and wires. But the USB A and B connector are backward compatible all the way to USB 1.0 1.5Mbit/s
- kevin_thibedeau 4y ago
  On-the-Go allows mini and micro B to be host as well.
LeonidasXIV 4y ago
USB-C is a connector type, like USB-A (usually known as the classic USB plug) and USB-B (usually the other side of said plug, a square kind of connector). USB-B had other offspring like miniUSB and microUSB (note that in these cases on the other side of the cable you usually have a USB-A plug). USB-C is the first time cables have the same connector on both sides, so it obsoletes USB-A and USB-B. But what is sent over USB-C? Can be USB 3 with which it is often conflated because they came around the same time, but it can also be USB 2, so it is a bit hard to tell. But USB 3 can use old style USB-A as well (the blue plugs with the same shape as the classic USB plugs) and USB-C (the microUSB plugs with an extension off to the side).
- microtonal 4y ago
  Can be USB 3 [...] USB 2, so it is a bit hard to tell. ...or Thunderbolt, USB 4, DisplayPort (through Alt-mode or encapsulated in Thunderbolt), or HDMI (Alt-mode), or MHL (Alt-mode), USB Power Delivery... Unfortunately, not every cable with USB-C connectors can carry all of these. E.g. there are USB-C cables that can only carry USB 2. Or cables that can carry USB 3, but not Thunderbolt. Also, not all cables can carry the same wattage for power delivery. It's a mess.

can16358p 4y ago

So on the next versions of USB, the cable length will get shorter and shorter until the max gets to 5cm? While I get the technical reasoning about high frequency/attenuation etc that limits cable length as speeds go higher, there are obviously some practical limits to how short cables can be. How would that be solved, I don't know.

CoastalCoder 4y ago
Not my area of expertise, but maybe some (unrealistic) options include using fiber optics for the data lines, or adding more data lines.
- birktj 4y ago
  There already exists some fiber-optic USB cables that come in lengths >50m and with support for USB 3.1 so it doesn't seem like a very unrealistic option.
  - Chilinot 4y ago
    That sounds more like fiber optic adapters/converters that fit into usb-ports and talk usb, rather than USB-cables that can be 50+ meters.
    - jayd16 4y ago
      Seems like you can get 3m optical usb-c cables. Oculus sells an official "Full featured USB active optical cable. USB 3.2 Gen 1 Type-C" for tethered play. That's what the cheatsheet says so maybe that's part of the spec.
    - jsjohnst 4y ago
      I think GP is thinking of fiber optic Thunderbolt cables probably.
    - duskwuff 4y ago
      Some USB4 / Thunderbolt cables are like that, but with copper in the middle. The drivers on the device end wouldn't be able to maintain signal integrity over that size of cable, so there's a pair of transceivers in each end of the cable to convert the signal into a format that'll survive transmission.

_joel 4y ago

I've definitely used 5m+ extensions on USB1 (and 2 iirc) before. I guess it'd be sketchy running something that requires decent throughput and not b0rk on ECC/FEC/whatever it uses but for temperature sensors which I was using, it was fine.

TonyTrapp 4y ago
A long time ago, I was using a USB 1 or 2 Wifi adapter through a USB extension cord, I'm pretty sure the total cable length was more than 5 meters. It "worked", but even just flicking a light switch caused the network connection to reset. So yeah, it may "work", for certain values of "work".

gsich 4y ago

CC1 and CC2 pins are missing.

megous 4y ago
They are not required to be wired through all cables. Similar to SBU signals.

Tepix 4y ago

I have a related question: Is the official name USB 3.2 Gen 2x2 or USB 3.2 Gen 2×2 (x vs ×)?

masklinn 4y ago
The USB pages and specs (on usb.org) seem to use "x" where they use the technical spelling.
jjoonathan 4y ago
Which USB do I choose for a 4x4 offroad adventure?

Villodre 4y ago

I'm always flabbergasted at how difficult and hostile to the user is discern between the various USB standards.

Someone 4y ago

No USB On-The-Go (https://en.wikipedia.org/wiki/USB_On-The-Go https://en.wikipedia.org/wiki/USB_On-The-Go) or Wireless USB (https://en.wikipedia.org/wiki/Wireless_USB https://en.wikipedia.org/wiki/Wireless_USB)? USB is a triumph of marketeers over engineers. All these things are called USB because USB sells (see also: Bluetooth).

ChrisRR 4y ago
Bluetooth Smart aka. Bluetooth Low Energy aka. Wibree aka. not actually bluetooth
IshKebab 4y ago
I don't know anything about wireless USB but USB OTG is called USB because it is USB. It's not some totally unrelated protocol.
- jandrese 4y ago
  I thought OTG was just changing up where the host controller is sitting in the USB relationship? So you can have a device that acts like a client when hooked to a computer, or a master when hooked to a thumb drive/webcam/etc...?
  - IshKebab 4y ago
    Yeah it just allows you to use a B port as a host (if supported). It's still the USB protocol.
    - cesarb 4y ago
      AFAIK, according to the standard you still cannot use the B port as a host, it should instead be an AB port (a socket in which both A and B plugs fit).
      - thatfunkymunki 4y ago
        i cannot find any examples of this kind of port, can you share a link?

Lucasoato 4y ago

Why didn't they focus enough on cable length? I'm not sure about how much latency they would add since the current is still traveling at light speed. Maybe there's someone in the world wondering if it's possible to emulate MarioKart from his office PC to the living room with a 10m HDMI and USB3 cable... Just guessing :)

stavros 4y ago

What does the U in USB stand for again?

theandrewbailey 4y ago
Unintuitive.
_joel 4y ago
Unintelligable
notorandit 4y ago
Uikipedia
jbverschoor 4y ago
U-turn
jbverschoor 4y ago
Actually, I think it’s just a upside down “∩”. Makes sense because the non-C connectors are always upside down, and all it does is intersect wires.

synergy20 4y ago

Like the simple site design with a one page info about USB. someone please make similar one-page with tables about PCI Express, Ethernet, HDMI...

NoXero 4y ago
I second that request!
ProZsolt 4y ago
I created a cheat sheet for Ethernet, when I built my home network: https://github.com/ProZsolt/runbook/blob/master/ethernet-cable.md https://github.com/ProZsolt/runbook/blob/master/ethernet-cab...
- navaati 4y ago
  Really nice ! Today I learn that there is a 25 and 40G-BASE-T on copper, these PHY must heat like hell haha.
- synergy20 4y ago
  shoud 100, 400, 800G be added, yes a bit earlier for 800G but I think 100/400G are already in use at data centers.
  - ProZsolt 4y ago
    This only covers twisted pair, as I only use this as reference when I need new endpoints in my or my parents house. I'll update the guide when I rewire my house with fiber optics (currently I don't even use the full potential of cat 6), but contributions are welcomed.

markus_zhang 4y ago

Is that year 2025...

a3w 4y ago
Nope, USB4 has been defined for a while now.

cosmotic 4y ago

Where's the standard speed?

IvanK_net 4y ago

Fun fact: USB 2.0 webcams have been existing for over 10 years. USB 2.0 is 60 MB/s. A pixel of an image is 3 Bytes. A 1920x1080 FullHD image is 6.2 MB. At 30 frames per second, second of a FullHD video is 186 MB. How did they do that? Answer: frames are transferred as JPEG files. Even a cheap $15 webcam is a tiny computer (with a CPU, RAM, etc), which runs a JPEG encoder program.

kevin_thibedeau 4y ago
The cheap ones are using hardware JPEG encoders. The associated micro isn't powerful enough to do it in firmware alone.
- masklinn 4y ago
  Surprised they don't use a hardware video encoder, is it because the well and efficiently supported formats are all MPEG, and thus have fairly high licensing cost on top of the hardware? Or because even efficient HVEs use more resources than webcams can afford? Or because inter-frame coding requires more storage, which (again) means higher costs, which (again) eats into the margin, which cheap webcam manufacturers consider not worth the investment?
  - martinmunk 4y ago
    My older Logitech C920 has an on-board H.264 encoder. Newer revisions of the same model does not. I haven't figured out why they chose to remove it, but your point about licensing cost combined with them not advertising it much as a feature, and most of their competitors not including "proper" video encoding might explain it. Edit: Found an official explanation here: https://www.logitech.com/en-us/video-collaboration/resources/think-tank/articles/article-logitech-and-h264-encoding.html https://www.logitech.com/en-us/video-collaboration/resources... TLDR, they figure most computers at that point had HW encoders.
    - lxgr 4y ago
      Unfortunately, this makes it much harder to use these as webcams on a Raspberry Pi (which even has H.264 hardware acceleration – the bottleneck is decoding the MJPEG stream from the camera, for which ffmpeg does not have hardware acceleration on the RPi).

moffkalast 4y ago

All it's missing is the pinouts and the charger resistor divider setup definitions.

Aragorn2331 4y ago

Hello Fabien ! I saw on twitter that you had built a gaming setup, can you write an article on your blog as you did for your silent pc ?

fabiensanglard 4y ago
I did build a PC last year especially to play Diablo2: Ressurected. I did write something at the time but never published it. Maybe I will clean it up.
fabiensanglard 4y ago
Here it is https://fabiensanglard.net/d2r/index.html https://fabiensanglard.net/d2r/index.html
- Aragorn2331 4y ago
  Amazing setup for amazing game ! Thanks for this post, i love to read you :-)

IshKebab 4y ago

This is wrong. For example Full Speed isn't a name for USB 1, it's the name for a speed which is supported by USB 1 and 2 (not sure about 3). Most USB microcontrollers are Full Speed USB 2.

JoeDaDude 4y ago

If only it included a guide to the different USB connectors, but that might make TFA too long to publish.

cesaref 4y ago

There's something about the naming of USB that is great. I love how there are now something like a dozen 'universal' standards, and how the serial bus now has multiple lanes.

dimman 4y ago

Thanks. Nit-picking here but ground is usually abbreviated GND, not GRD.

datastack 4y ago

Hi, nice cheatsheet! I've published it on DataStack, where anyone can contribute improvements (like adding columns or corrections). https://datastack.net/datastack/usb https://datastack.net/datastack/usb I can transfer the project to you if you like.

joshspankit 4y ago

If you don’t mind sharing: what was the “bug”?

PowerBar 4y ago

In the "USB-A/B" section, they're all labelled "Type-A", the 3rd and 4th should be labelled "Type B". It's also missing - mini-b 4 wire (older phones, etc) - micro-b 4 wire (most electronics prior to type c) - micro-b 8 wire (mostly seen only found on external 2.5" HDDs) There were also a bunch of other connectors (mini-a, mini-a/b, etc) but they are very rare.