[HN Gopher] USB Cheat Sheet
___________________________________________________________________
USB Cheat Sheet
Author : WithinReason
Score : 308 points
Date : 2022-05-05 08:43 UTC (14 hours ago)
(HTM) web link (fabiensanglard.net)
(TXT) w3m dump (fabiensanglard.net)
| synergy20 wrote:
| 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 wrote:
| I second that request!
| ProZsolt wrote:
| I created a cheat sheet for Ethernet, when I built my home
| network:
| https://github.com/ProZsolt/runbook/blob/master/ethernet-cab...
| synergy20 wrote:
| 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 wrote:
| 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.
| navaati wrote:
| Really nice !
|
| Today I learn that there is a 25 and 40G-BASE-T on copper,
| these PHY must heat like hell haha.
| dschuetz wrote:
| 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).
| Tepix wrote:
| Good question. I bought a RaidSonic Icy Box IB-1121-C31 USB 3.1
| (10Gbit) S-ATA dock recently (with a USB Type C connector) that
| came with a USB C cable and had a buy a special "USB-A - USB
| type C cable" to achieve 10Gbit/s with the 10GBit/s USB A
| connector of my mainboard.
|
| The "USB A - USB type C cables" that i had already only worked
| up to 480MBit/s.
| hyperman1 wrote:
| 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 wrote:
| On-the-Go allows mini and micro B to be host as well.
| LeonidasXIV wrote:
| 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).
| LordDragonfang wrote:
| >note that in these cases on the other side of the cable you
| usually have a USB-A plug
|
| Usually a _full-size_ USB-A, you mean, because what we
| commonly know as mini-USB and micro-USB are actually mini-B
| and micro-B, which have corresponding (but now rarely used)
| micro-A and micro-A ports. Before USB-OTG, USB used to be an
| explicitly directional protocol, with a master and a slave
| device.
|
| https://upload.wikimedia.org/wikipedia/commons/8/82/USB_2.0_.
| ..
|
| https://en.wikipedia.org/wiki/USB_hardware
| danieldk wrote:
| _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.
| jasomill wrote:
| Worse, there are no "best" cables longer than 0.5m: any
| longer than that, Thunderbolt 3 requires active cables
| which don't pass non-Thunderbolt data beyond, IIRC, 480
| Mbps.
|
| As someone who spent many years using a mix of
| 25/50/68/80-pin fast/ultra/... single-ended, LVD and HVD
| parallel SCSI devices, however, USB-C/Thunderbolt cabling
| _still_ feels like a breath of fresh air.
| danieldk wrote:
| I think Thunderbolt 4 active cables are supposed to pass
| higher USB 3 speeds? At least the Apple Thunderbolt 4
| cable claims to do so:
|
| https://www.apple.com/shop/product/MN713AM/A/thunderbolt-
| 4-p...
| nolok wrote:
| There was a period of time where a google engineer was
| producting review on amazon about which usb-c cable would
| make your laptop burn. That was fun, and totally not the
| sign of an overbloated standard.
| cesarb wrote:
| IIRC, that particular cable was one which had its power
| wired to the ground pin and ground wired to the power
| pin. No standard can help you if the cable is that badly
| made.
|
| (The effect of that miswiring is to apply a negative
| voltage, around -5V, to a chip most probably designed for
| a range of -0.5V to 20.5V; which results in a short
| circuit through at least the ESD protection diodes within
| the chip, and possibly other parts of the chip too.)
| Dylan16807 wrote:
| Yep, a batch of cables having the super basic power pins
| wired backwards tells you basically nothing about the
| standard, no matter how often people try to use it as
| evidence of complication.
|
| And the docks that were frying switches were putting 9
| volts on a signal pin, also obviously wrong.
| rob74 wrote:
| Of course USB-C makes this worse, but the problem already
| started earlier: a few years ago I connected my phone to my
| computer with a USB-A to micro USB cable and was scratching
| my head why it didn't work. Then I remembered that the
| cable had come with some Bluetooth headphones and was only
| a charging cable without data lines...
| colejohnson66 wrote:
| Desktop speakers do this still. Instead of simply being a
| USB speaker set, they use the line out jack for audio and
| a USB plug for power.
| LordDragonfang wrote:
| There's actually a reason for that. Standard USB can
| (obviously) only transfer digital audio, and most
| speakers are "dumb" devices designed to just amplify an
| analog signal. In order to convert digital to analog, you
| need a DAC (Digital-to-Analog-Converter), and good DACs
| are still a nontrivial cost to a manufacturer, so
| whatever DAC you already have in your computer is
| probably better than the crappy one that would come with
| cheap consumer speakers.
| izacus wrote:
| Funny enough, USB-C can transport analogue audio over USB
| cable though :)
|
| Tends to be too expensive for the cheapest of products.
| willis936 wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| 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-
| follo...
|
| https://www.youtube.com/watch?v=qo9Y7AMPn00
| hdjjhhvvhga wrote:
| If you think it's not complicated enough, add Thunderbolt to it.
| CharlesW wrote:
| Thunderbolt 4 is effectively USB 4.
| https://www.cablematters.com/blog/Thunderbolt/usb4-vs-thunde...
| netsharc wrote:
| 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?
| izacus wrote:
| 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.)
| doubled112 wrote:
| 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.
| cosmotic wrote:
| Where's the standard speed?
| can16358p wrote:
| 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.
| moffkalast wrote:
| Keep the same speeds, add more wires.
| [deleted]
| CoastalCoder wrote:
| Not my area of expertise, but maybe some (unrealistic) options
| include using fiber optics for the data lines, or adding more
| data lines.
| birktj wrote:
| 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 wrote:
| 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.
| Dylan16807 wrote:
| What's the difference between talking USB and being USB?
| duskwuff wrote:
| 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.
| michaelt wrote:
| https://www.amazon.com/FIBBR-Female-Active-Extension-
| Optical... provides USB-to-fibre-to-USB in a single
| cable, and a copper pair in parallel for power.
| jayd16 wrote:
| 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 wrote:
| I think GP is thinking of fiber optic Thunderbolt cables
| probably.
| BolexNOLA wrote:
| Redmere chips also proved HDMI can go very, very far with a
| little extra investment. I've run 4K signals hundreds of
| feet with them. We've seen this problem solved several
| times, I can't imagine it's physically impossible with
| USB-C.
| dual_dingo wrote:
| I guess at some point optical will be the only way forward.
|
| Having more data lines in a serial bus is interesting, as the
| whole reasoning to go from parallel lines (e.g. Centronics,
| ATA/SCSI or ISA/PCI buses) to serial (SATA/SAS, PCIe, USB)
| was that coordinating multiple data lines got impossible due
| to physical limitations where e.g. minimal differences in
| cable lengths started to matter).
| Dylan16807 wrote:
| > I guess at some point optical will be the only way
| forward.
|
| Maybe. Though Infiniband's currently at 100Gbps per lane on
| a 1.5 meter passive cable. And active cables can give you a
| moderate boost while still on copper.
| paulmd wrote:
| that's a giant QSFP+ cable (I think mine are at least
| 3/8") with tons of shielding and a terrible bend radius
| though.
|
| And my cables all have a "10 plug/unplug cycle lifespan"
| sticker on them - it undoubtedly will go for longer in
| practice but it's not designed for USB-style usage where
| you might plug and unplug your phone a dozen times a day
| as you charge it.
|
| Commercial design concerns are very different from
| consumer design concerns, basically. Phones would
| probably be easier if we had a 1/2" x 1/2" x 1.5"
| connector with a shielded connector body! ;)
| helpm33 wrote:
| Multiple serial busses, each with its own clocking and
| buffer, so that the combined data is extracted
| synchronously at the end. The crosstalk is still a problem
| but there are ways around that: different twist rates for
| different pairs for instance.
| legalcorrection wrote:
| 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 wrote:
| > 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 wrote:
| 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 wrote:
| Some of the entries seem incorrect: "USB 3.2 (USB 3.2 Gen 2x2)
| and "USB 4" (USB 4 USB4 Gen 2x2) 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).
| belter wrote:
| Also should be:
|
| 12 Mbps -> 1.43 MiB/s -> 1.5 MB/s
|
| 480 Mbps -> 57 MiB/s -> 60 MB/s
|
| 5000 Mbps (5 Gbps) -> 596 MiB/s -> 625 MB/s
|
| 10000 Mbps (10 Gbps) -> 1192 MiB/s -> 1250 MB/s
|
| 20000 Mbps (20 Gbps) -> 2384 MiB/s -> 2500 MB/s
|
| 40000 Mbps (40 Gbps) -> 4768 MiB/s -> 5000 MB/s
| adrian_b wrote:
| No, some of your rates are wrong.
|
| The so-called 5 Gb/s USB has a data rate of 4 Gb/s.
|
| The marketing data rates for Ethernet are true, i.e. 1 Gb/s
| Ethernet has a 1 Gb/s data rate, but a 1.25 Gb/s encoded bit
| rate over the cable.
|
| The marketing data rates for the first 2 generations of PCIe,
| for all 3 generations of SATA, and for USB 3.0 a.k.a. "Gen 1"
| of later standards, are false, being advertised as larger
| with 25% (because 8 data bits are encoded into 10 bits sent
| over the wire, which does not matter for the user).
|
| All these misleading marketing data rates have been
| introduced by Intel, who did not follow the rules used in
| vendor-neutral standards, like Ethernet.
|
| So PCIe 1 is 2 Gb/s, PCIe 2 & USB 3.0 are 4 Gb/s and SATA 3
| is 4.8 Gb/s.
|
| So USB "5 Gbps" => 500 MB/s (not 625 MB/s), and after
| accounting for protocols like "USB Attached SCSI Protocol",
| the maximum speed that one can see for an USB SSD on a "5
| Gbps" port is between 400 MB/s and 450 MB/s.
|
| The same applies for a USB Type C with 2 x 5 Gb/s links.
|
| As other posters have already mentioned, USB 3.1 a.k.a. the
| "Gen 2" of later standards has introduced a more efficient
| encoding, so its speed is approximately 10 Gb/s.
|
| The "10 Gbps" USB is not twice faster than the "5 Gbps" USB,
| it is 2.5 times faster, and this is important to know.
| fabiensanglard wrote:
| I should add Nominal vs Raw vs Effective speed to the
| table.
|
| Can you confirm with the rule to be used.
|
| Raw Speed = Nominal / Encoding
|
| UMS Speed = Raw / UMS overhead
|
| In the case of 3.0 that would be:
|
| Nominal = 625 MiB/s
|
| Raw = 625 - 20% = 500 MiB/s
|
| UMS = 500 - 20% = 400 MiB/s
| adrian_b wrote:
| The names for the various bit rates vary between authors
| and standards.
|
| I believe that the least confusing names would be:
|
| Data bit rate = the rate at which the data bits provided
| by the user are sent
|
| Signaling bit rate = the rate at which bits are sent over
| the physical communication medium
|
| The 2 rates are not the same because the user data bits
| are encoded in some way before being sent. The signaling
| bit rate does not have any importance, except for those
| who design communication equipment. For the users of some
| communication equipment, only the data bit rate matters.
|
| The data bit rate is equal to the signaling bit rate
| multiplied by the ratio between data bits and the
| corresponding encoded bits.
|
| For example, for USB 3.0 (single link Gen 1):
|
| Signaling bit rate = 5 Gb/s
|
| Data bit rate = (5 * 8 / 10) Gb/s = 4 Gb/s
|
| Data byte rate = (4 / 8) GB/s = 500 MB/s = 477 MiB/s
|
| 5 Gb/s corresponds to 625 MB/s, but for a signaling bit
| rate it is completely useless to convert bits to bytes,
| because groups of 8 bits on the physical communication
| medium do not normally correspond to bytes from the data
| provided by the user. Only for the data bit rate it is
| meaningful to be converted to a data byte rate.
|
| For USB 3.1 (single link Gen 2):
|
| Signaling bit rate = 10 Gb/s
|
| Data bit rate = (10 * 128 / 132) Gb/s = 9.7 Gb/s
|
| Data byte rate = (9.7 / 8) GB/s = 1212 MB/s = 1156 MiB/s
| jbverschoor wrote:
| Is that the same intel that "forgot" to mention that they
| overclocked a demo cpu and used ndustrial water chiller?
| ridgered4 wrote:
| My favorite is when Intel demoed the new ivybridge iGPU
| by having a guy fire up VLC player to play some footage
| of a racing game while he pretended to control it with a
| steering wheel controller.
|
| I looked this up and it's actually even worse than than I
| thought. When called out he claimed it was being control
| from backstage.
|
| https://www.techpowerup.com/158448/that-dodgy-intel-ivy-
| brid...
| asciii wrote:
| I was curious and went looking for it. That's pretty
| hilarious oversight!
|
| https://www.tomshardware.com/news/intel-28-core-
| cpu-5ghz,372...
| jbverschoor wrote:
| Lol that's hilarious
| CamperBob2 wrote:
| 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 wrote:
| 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).
| [deleted]
| fabiensanglard wrote:
| Thank you for noticing these issues, I have updated the table.
|
| I would be happy to improve it and add encoding. I am surprised
| by some of the summary entries on Wikipedia
| (https://en.wikipedia.org/wiki/USB4). Looks like USB4
| "reverted" to 128b/132b. It is accurate?
| lxgr wrote:
| 128b/132b is the more efficient coding. The closer to 1 the
| fraction is, the less coding overhead it has, and 128/132 is
| larger than 8/10.
| fabiensanglard wrote:
| Actually, I just noticed that 128/132 is the same fraction
| as 66/64 so both scheme has the same encoding efficiency.
| So USB-4 did no "revert in terms of efficiency.
| 0xTJ wrote:
| 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.
| Villodre wrote:
| I'm always flabbergasted at how difficult and hostile to the user
| is discern between the various USB standards.
| markus_zhang wrote:
| Is that year 2025...
| a3w wrote:
| Nope, USB4 has been defined for a while now.
| cesaref wrote:
| 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.
| moffkalast wrote:
| All it's missing is the pinouts and the charger resistor divider
| setup definitions.
| dimman wrote:
| Thanks. Nit-picking here but ground is usually abbreviated GND,
| not GRD.
| Aragorn2331 wrote:
| 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 wrote:
| 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.
| Someone wrote:
| No USB On-The-Go (https://en.wikipedia.org/wiki/USB_On-The-Go) or
| 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 wrote:
| Bluetooth Smart aka. Bluetooth Low Energy aka. Wibree aka. not
| actually bluetooth
| IshKebab wrote:
| 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 wrote:
| 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 wrote:
| Yeah it just allows you to use a B port as a host (if
| supported). It's still the USB protocol.
| cesarb wrote:
| 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).
| paulmd wrote:
| I had an iRiver H320 with USB-OTG support. At the time I
| thought it was just a straight-up mini-B port but you're
| right, that's actually a mini-AB port!
|
| https://www.guru3d.com/miraserver/images/reviews/soundcar
| ds/...
|
| I am not sure I have ever seen mini-A anywhere.
|
| God, what a wacky standard. (USB-OTG specifically but
| really USB plugs in general)
| jcrawfordor wrote:
| Another example of mini-AB is the TI-84 series. Two
| calculators can be directly connected but a USB A-A cable
| is verboten by the spec (although I sometimes see them
| nonetheless), so TI put an AB port on the calculator and
| sold a mini-A to mini-B cable. It is somewhat confusing
| to users that a cable with two different ends was
| nonetheless completely transposable.
|
| I'm not sure of this at all but I sort of doubt the TI-84
| used spec compliant OTG, because in general the USB
| implementation on that calculator was very weird and
| unreliable and gave the feeling that they were doing
| something uncouth like bit-banging and not quite fast
| enough. I remember it routinely taking multiple attempts
| to get something to transfer successfully.
| thatfunkymunki wrote:
| i cannot find any examples of this kind of port, can you
| share a link?
| paulmd wrote:
| iriver h320
|
| https://www.guru3d.com/miraserver/images/reviews/soundcar
| ds/...
| jandrese wrote:
| It is one of these connectors:
|
| https://en.wikipedia.org/wiki/USB_hardware#USB_On-The-
| Go_con...
|
| But every OTG device I have ever used has just used the
| USB-A port.
| [deleted]
| _joel wrote:
| 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 wrote:
| 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".
| Lucasoato wrote:
| 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 :)
| IvanK_net wrote:
| 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.
| pseudosavant wrote:
| Most webcams, especially 10 years ago are not 1080p, or even
| 60fps. Many aren't even 720p. 1280 x 720 x 3 bytes x 30 fps =
| ~80MB/second. 480p @ 30 fps = 26MB. That is how many webcams
| can get by without hardware JPEG/H264 encoding.
|
| 4K @ 60fps = 1.4GB/sec. USB 3, even with 2 lanes, will have
| trouble with that.
| grishka wrote:
| Hm. But then wouldn't it make more sense to just stream the raw
| sensor data, which is 1 byte per pixel (or up to 12 bits if you
| want to get fancy), and then demosaic it on the host? Full HD
| at 30 fps would be 59.33 MB/s, barely but still fitting into
| that limit.
|
| But then also I think some webcams use H264? I remember reading
| that somewhere.
| BayAreaEscapee wrote:
| I don't know where you get "1 byte per pixel" from. At
| minimum, raw 4:2:0 video would be two bytes per pixel, and
| RGB would be three bytes per pixel with 8-bit color depth.
| Dylan16807 wrote:
| When talking about digital cameras, each "pixel" is a
| single color sensor. Blame marketing.
|
| Also 4:2:0 is 6 values per 4 pixels. 1.5 bytes per pixel at
| 8-bit.
| nybble41 wrote:
| You're talking about processed color frames. The GP was
| suggesting that the camera stream the raw sensor data,
| which doesn't have individual color channels, just a
| monochrome grid with 10 or 12 bits of usable data per
| pixel. A bayer filter[0] is placed in front of the sensor
| so that a given color of light falls on each cell. The USB
| host would be responsible for applying a demosaicing[0]
| algorithm to create the color channels from the raw sensor
| data.
|
| If we take the AR0330 sensor used in the USB Camera C1[2]
| as an example, it has a native resolution of 2304H x 1296V
| and outputs 10 bits per native pixel after internal A-Law
| compression[3] for a total raw frame size of 3.56 MiB,
| assuming optimal packing. The corresponding image,
| demosaiced and downscaled to Full HD (1920x1080), in RGB
| with eight bits per channel would be 5.93 MiB.
|
| [0] https://en.wikipedia.org/wiki/Bayer_filter
|
| [1] https://en.wikipedia.org/wiki/Demosaicing
|
| [2] https://www.kurokesu.com/shop/cameras/CAMUSB1
|
| [3] https://www.onsemi.com/products/sensors/image-
| sensors/ar0330
| masklinn wrote:
| > it has a native resolution of 2304H x 1296V
|
| Seems to me like that kills the idea dead? GGP assumed
| 8bpp and that the raw resolution matched the output, and
| came out... well wrong (the effective bulk transfer rate
| of USB 2.0 is 53MB/s on a good day), but by just a few
| megs.
|
| However the raw resolution is 40% higher than the final
| output, meaning even at 8bpp you're at 85MB/s and you've
| blown way past any hope of recovering via a few tricks.
| At 10 bpp you're above 100MB/s.
| nybble41 wrote:
| Native resolution at 10bpp requires 40% less data per
| frame than the final Full HD RGB output at 8bpp per
| channel (24bpp total), so it would represent some
| savings.
|
| The problem is that neither format fits within the limits
| of USB 2.0 at 15 FPS or higher. To achieve a reasonable
| framerate you need to apply compression, and generally
| speaking you'll get better compression if you demosaic
| first.
| monocasa wrote:
| The pixel density doesn't generally refer to the density of
| the Bayer pattern, which can be even denser. Generally a
| cluster of four Bayer pixels makes up one pixel (RG/GB), but
| like most things in computing, the cognitive complexity is
| borderline fractal and this is a massive simplification.
| Dylan16807 wrote:
| > Full HD at 30 fps would be 59.33 MB/s, barely but still
| fitting into that limit.
|
| That limit is too high even as a theoretical max.
|
| You _could_ do raw 720p.
| masklinn wrote:
| > Full HD at 30 fps would be 59.33 MB/s, barely but still
| fitting into that limit.
|
| It's not fitting into anything I fear, best case scenario the
| _effective_ bulk transfer rate of USB2 is 53MB /s.
|
| 60 is the signaling rate, but that doesn't account for the
| framing or the packet overhead.
| verall wrote:
| It would need a funny driver and since that stuff is big
| parallel image processing it's easy in HW but if someone has
| a netbook or cheap/old Celeron crap it would peg their CPU to
| do the demosaic and color correction.
| kevin_thibedeau wrote:
| The cheap ones are using hardware JPEG encoders. The associated
| micro isn't powerful enough to do it in firmware alone.
| masklinn wrote:
| 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?
| izacus wrote:
| MJPEG is just a very simple "video" format that needs very
| simple and cheap electronics to work. Video encoding blocks
| are mostly part of bigger SoCs and comes with licensing
| costs.
|
| Same goes on the other hand for the receiving end -
| decoding a stream of JPEGs is just much simpler in both CPU
| use and code complexity than dealing with something like
| H.264.
| martinmunk wrote:
| 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... TLDR, they figure most computers
| at that point had HW encoders.
| lxgr wrote:
| 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).
| broomhall wrote:
| As an alternative to ffmpeg, GStreamer provides hardware
| accelerated MJPEG decoding on the Pi. I think there are
| bugs, though, which makes it unsuitable for some use
| cases. Here's an example pipeline - https://forums.raspbe
| rrypi.com/viewtopic.php?p=1989575#p1989...
| verall wrote:
| It needs a uC with some special hardware anyways to do demosaic
| or else it would require special drivers that would peg some
| people's crappy laptop CPUs.
|
| Also the raw YUV 4:2:0 is 1.5 bytes per pixel so that's doing
| half of the "compression" work for you.
| JoeDaDude wrote:
| If only it included a guide to the different USB connectors, but
| that might make TFA too long to publish.
| eugene3306 wrote:
| just curious. Can USB3 work without D+ and D- ?
| [deleted]
| formerly_proven wrote:
| 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 wrote:
| 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 wrote:
| 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.
| stavros wrote:
| What does the U in USB stand for again?
| jbverschoor wrote:
| 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.
| theandrewbailey wrote:
| Unintuitive.
| _joel wrote:
| Unintelligable
| notorandit wrote:
| Uikipedia
| jbverschoor wrote:
| U-turn
| Kab1r wrote:
| USB versioning is such a clusterfuck.
| 411111111111111 wrote:
| 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 wrote:
| 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 wrote:
| Apple just released a EUR159 cable
| paulmd wrote:
| 3m is beyond the max cable length specified by
| Thunderbolt, so it requires active extenders (they're
| hidden in the plugs) and tight manufacturing and
| shielding. You're paying extra for the ability to break
| that max length spec, and it's one of only a handful of
| products that do it.
|
| The only other one I'm aware of is the Corning Active
| Optical Cable series which costs $360 for a 10m
| Thunderbolt 3 cable or $479 for a 30m cable, or $215 for
| a 10m Thunderbolt 2 cable (ie slower and different
| connector, potentially needs a $50 converter on each
| end). Also those Corning cables have a reputation for
| failing _barely_ out of warranty even if they are treated
| very delicately. Amazon reviews are _full_ of "my cable
| failed 1 year and 1 month after purchase and Corning told
| me to go eat a dick" type reviews.
|
| https://www.bhphotovideo.com/c/product/1577008-REG/optica
| l_c...
|
| Also, just FYI, but max length spec on a USB 4 cable
| (which will support Thunderbolt-like features) is 0.8m
| and you'll need to use special cables to get the full
| capabilities there too, you can't just use a $15 usb-c to
| usb-c cable you bought off amazon. Just like some usb-c
| cables only support usb 2.0 speeds, you won't get full-
| duplex 40gbps signaling out of a 10gbps half-duplex USB
| 3.1 cable. USB certification isn't magic, these are
| physics-based electrical/RF problems here and high-
| capability cables/devices require more expensive
| implementations.
|
| But anyway go ahead and click through that B+H link and
| look through their thunderbolt 3 cable category for
| another 3-meter cable. You won't find any. If 2 meters is
| not enough... your options are Apple, Corning, or
| nothing.
|
| The Apple premium is still a thing, but I'd expect
| competitors to clock in around $100 if/when they come
| out. There is always a steep price inflection once you
| move from passive cables to active cables or fiber. If
| you can avoid that, great, use a shorter cable. If you
| can't, you have to pay up. Not everyone can just move
| everything closer (eg running through walls) and it's
| always so disappointing to see people arguing _against
| consumers having options_ just because they don 't
| personally need them. No one is making you buy this, but
| the people who do now have an option they didn't before.
| That "if I'm not interested in a product then it
| shouldn't exist at all!" mindset seems to be extremely
| pervasive in the tech space and I just don't get it, not
| every product has to be aimed at you personally. It's
| "center of the universe syndrome" as one of my teachers
| liked to call it.
|
| I've looked at the Corning cables for setting up a Vive
| Wireless Adapter that can be in a different room from my
| desktop rig (adapter goes in a Thunderbolt enclosure,
| mounted on the wall, thunderbolt optical cable goes
| through the walls...) but the price and the failures
| kinda scared me off. I get that this won't work for
| normies, but personally I'd prefer to have the
| transceivers and the fiber be separate so I can replace
| one or the other if needed. Shipping it pre-assembled is
| fine but given we're talking about a $500 investment here
| I'd want it to not break in a year or at least to be
| semi-repairable if it does.
| Dylan16807 wrote:
| > 3m is beyond the max cable length specified by
| Thunderbolt, so it requires active extenders (they're
| hidden in the plugs) and tight manufacturing and
| shielding. You're paying extra for the ability to break
| that max length spec, and it's one of only a handful of
| products that do it.
|
| I'm pretty sure it's not breaking the spec. Are you sure
| about that claim?
|
| And the main factor is almost always decibels of signal
| loss rather than length, isn't it?
|
| > Also those Corning cables have a reputation for failing
| barely out of warranty even if they are treated very
| delicately. Amazon reviews are full of "my cable failed 1
| year and 1 month after purchase and Corning told me to go
| eat a dick" type reviews.
|
| My understanding is that the thunderbolt 2 ones reliably
| self-destruct but the thunderbolt 3 ones probably fixed
| it? At the very least they can take a lot of physical
| abuse.
|
| > 10gbps half-duplex USB 3.1 cable
|
| I don't think any of the high speed wires are ever half
| duplex?
| paulmd wrote:
| > I'm pretty sure it's not breaking the spec. Are you
| sure about that claim?
|
| Actually we're both wrong... it appears max length for a
| passive cable is 18 inches for full performance. Passive
| cables technically max out at 18 inches for 40gbps and
| drop to 20gbps at 2 meters. Past that you need an active
| cable (which has signal repeaters).
|
| Active cables generally run up to 2 meters (the Apple is
| the first 3m active cable except for the Corning AOC
| cables), but in most cases (everyone except apple) you
| start dropping features like USB 3.1 or displayport.
| AFAIK Apple's solutions are unique in that they don't -
| like for example I looked up a 2 meter Belkin cable
| advertised as TB3 and it doesn't carry the DisplayPort
| channel.
|
| Which is why the advice for Thunderbolt is "just shut up
| and pay apple their money".
|
| https://appleinsider.com/articles/17/08/15/psa-
| thunderbolt-3...
|
| Not absolutely positive what the official standard is -
| they might well only say the passive number (ie 18
| inches) because active can obviously be more or less
| arbitrarily long with things like fiber, it might not
| make sense to define a maximum cable length in that
| context. Or they might amend it as they go... obviously
| Apple has now broken the 2 meter barrier with their
| active copper cable.
|
| I thiiiiink this becomes 0.8m for a passive cable in
| USB4/TB4 as the official passive spec? CableMatters seems
| to have a 2 meter active cable out though.
|
| > I don't think any of the high speed wires are ever half
| duplex?
|
| High-speed is half-duplex, yeah. It looks like SuperSpeed
| is full-duplex though so I'm wrong on that bit.
|
| I just remember it being a nightmare trying to use USB
| external hard drives (which would have been back in the
| USB 2.0/High-speed era when I used them last!) and
| reading/writing at the same time tanked performance _far_
| beyond what you 'd get with even an internal HDD. Read or
| write, one at a time, mixing both was a trip to hell.
|
| https://www.ramelectronics.net/USB-3.aspx
| Dylan16807 wrote:
| > Actually we're both wrong... it appears max length for
| a passive cable is 18 inches for full performance.
| Passive cables technically max out at 18 inches for
| 40gbps and drop to 20gbps at 2 meters. Past that you need
| an active cable (which has signal repeaters).
|
| I'm still pretty sure it's based on signal loss, and the
| lengths are just estimates of what you can reliably get
| out of a cost-optimized manufacturing process.
|
| > High-speed is half-duplex, yeah. It looks like
| SuperSpeed is full-duplex though so I'm wrong on that
| bit.
|
| By "the high speed wires" I mean the pairs introduced
| with USB 3. Not USB's dumb naming conventions.
|
| > I just remember it being a nightmare trying to use USB
| external hard drives (which would have been back in the
| USB 2.0/High-speed era when I used them last!) and
| reading/writing at the same time tanked performance far
| beyond what you'd get with even an internal HDD. Read or
| write, one at a time, mixing both was a trip to hell.
|
| I think a big part of that is also the mass storage
| protocol combined with slow responses off a hard drive. I
| have a USB 2.0 SSD-class drive around here and it
| actually performs pretty well even on mixed workloads.
| bombela wrote:
| Can you use USB3 (whatever gen crap it is) for this
| application maybe?
|
| I can drive an occulus quest2 via 8m of USB3 cable. The
| cable contains a fiber optic with a repeater hidden
| inside the female end. The total bandwidth this way is
| enough for the occulus quest2 at 90fps.
| paulmd wrote:
| The goal here is wireless, a single thinner cable would
| be better but it's better to not have to worry about
| wires at all. And I'm not willing to set up a facebook
| account just for a Quest.
|
| The Vive Wireless Adapter (VWA) is a PCIe card (single
| slot/low profile/mitx length). The output from the card
| is an SMA connector with a RF signal that goes to the
| antenna, max official length is 2 meters (and it isn't
| another SMA on the other end, it's hardwired into the
| antenna, so you have to use an extension, meaning
| multiple SMA connectors in the middle). I've seen people
| use some fairly long extension cables, but that
| attenuates the signal somewhat. It's _probably_ fine but
| it 's undesirable.
|
| There are USB wireless adapters (TPLink makes one iirc)
| but generally they are agreed to be an inferior solution
| in various respects - higher CPU usage, higher latency,
| worse signal quality, a green bar on the top, etc. This
| is basically an ideal use-case for WiGig, it was
| literally designed to be a wireless display transmitter,
| and that's what the Vive Wireless Adapter uses inside,
| it's actually an off-the-shelf Intel WiGig card. The
| TPCast uses a much lower-bandwidth solution and
| compresses it much harder and that requires more latency,
| more oomph on the PC, and still gets a worse signal
| quality.
|
| But, the WiGig card only has a short cable to the
| antenna. Solution: put the card in an enclosure and mount
| the enclosure on the wall, run the cables to the PC.
| Problem: thunderbolt also only runs 2 meters. Solution:
| optical thunderbolt cables. The rest is solvable from
| there.
|
| The other reason I haven't raced into it is that HTC
| hasn't kept it up with the newer hardware. The Vive Pro
| has a higher-res screen and the VWA can only run at
| (iirc) 3/4ths resolution. It's still a better screen,
| there's less Screen Door Effect, but when you're talking
| about dropping around $1000 to get wireless working
| flawlessly and tucked away into the walls, it better be
| fucking flawless. On paper the WiGig actually has three
| channels and should be able to send on all three at once,
| but this doesn't seem to be implemented...
|
| Honestly the TPCast is probably a 90% solution, it
| probably chokes on the Vive Pro as well but maybe for
| $200 instead of $1000 that's acceptable. But it's tough
| for me to accept "good enough" when there's a technically
| better solution. The VWA is an absolutely ideal solution
| here. At one point there were some updates pushed that
| looks like Valve was working on it, but (with apologies
| to South Park)... in typical Valve fashion, "they just
| sort of got high, and wandered off..."
|
| And then, the Index is just an all-around better
| headset... but it doesn't have a wireless solution at all
| right now (apart from maybe the TPCast?). It kinda sucks,
| drives me up the wall that there's no "perfect answer"
| here. Every solution has some large downsides.
| jsjohnst wrote:
| 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 wrote:
| FWIW, Monoprice's 1m USB4/TB4 cable (100W) is $25.
|
| https://www.monoprice.com/product?p_id=41946
| username190 wrote:
| Apple's cable is 3m, which is likely most of why it's
| more expensive.
|
| https://www.apple.com/shop/product/MWP02AM/A/thunderbolt-
| 4-p...
| jsjohnst wrote:
| Their 1.8m cable is $129, so still >2x the price of
| competitors. It's an extremely well made cable, but
| overkill, probably?
| [deleted]
| a3w wrote:
| USB 4 (opt) is ... optical? Or optional?
| willis936 wrote:
| It would have a longer max length if the data lanes were
| optical.
| johnwalkr wrote:
| 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 wrote:
| > 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 wrote:
| 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/...
| mschuster91 wrote:
| Whoa, that pricing is quite a bit.
| johnwalkr wrote:
| 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-
| acciden...
| mschuster91 wrote:
| > Kind of hilarious now, seeing how thunderbolt 1/2 ended
| up barely being adopted outside of Apple
|
| Which is to a large degree the fault of Intel restricting
| the TB spec to hell and back.
| masklinn wrote:
| According to the wiki table (https://en.wikipedia.org/wiki/USB4
| #Support_of_data_transfer_...), it's "optional":
|
| * "USB4 20 Gbit/s Transport" (= USB4 20Gbps = USB4 Gen 2x2) is
| required for host to support
|
| * "USB4 40 Gbit/s Transport" (= USB4 40Gbps = USB4 Gen 3x2) is
| not
|
| Also USB4 apparently only requires support for tunneling
| "SuperSpeed USB 10Gbps" (USB 3.2 Gen 2x1), "SuperSpeed USB
| 20Gbps" (USB 3.2 Gen 2x2) is optional.
| kashunstva wrote:
| > May 05, 2025
|
| The article is dated May 5, 2025. I've long been wondering about
| the future of USB.
| Beta-7 wrote:
| 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.
| notorandit wrote:
| Not to be read before: see article time stamp
| vesinisa wrote:
| OP forgot [2025] from the title.
| WithinReason wrote:
| I could still fix it, but I fear the wrath of Dang
| Fatnino wrote:
| 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.
| IshKebab wrote:
| 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.
| gsich wrote:
| CC1 and CC2 pins are missing.
| megous wrote:
| They are not required to be wired through all cables. Similar
| to SBU signals.
| Tepix wrote:
| I have a related question:
|
| Is the official name
|
| USB 3.2 Gen 2x2
|
| or
|
| USB 3.2 Gen 2x2
|
| (x vs x)?
| jjoonathan wrote:
| Which USB do I choose for a 4x4 offroad adventure?
| masklinn wrote:
| The USB pages and specs (on usb.org) seem to use "x" where they
| use the technical spelling.
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(page generated 2022-05-05 23:00 UTC)