USBefuddled: Untangling the Rat’s Nest of USB-C Standards and Cables


In practice it has never been smoother for me. If I come across a crappy cable that isn't up to snuff I can easily get rid of it, I already have more than I need. It's not like previously when you had to keep some rare cables in case you needed them once in a blue moon.


I'm the same way in that I just have a collection of quality cables that do pretty much everything one could reasonably ask (i.e. excluding obviously special things like "I needed an optical thunderbolt cable to deliver 40 Gbps 20 meters why isn't it delivering 90 watt PD as well!") however I can see for those that don't want to spend a lot of money (keep in mind "a lot" is extremely relative) on a bunch of cables and just want to use the cheap cables they accumulate the lack of being able to easily look at such cables and see what they are capable of without a secret decoder ring as a frustrating thing type c brought. At least with the older ones either looked like it would fit or it wouldn't or the color of the ends matched.


You made me think of my own experience and indeed I realize since usb-c how much better connecting things has been. I'm down to one micro USB device and connecting to it is so annoying. USB-c is great, and I hope Apple products switch too so there is truly a single cable type to connect everything.


I use a little usb-c to micro USB adapter for my only remaining devices, though I plan on converting them to usb-c.


Agreed. Being able to drive two 4K monitors, charge my laptop, and attach a USB hub via one USB-C connector is well worth the tradeoff of occasional incompatibility with cheap cables.


I love usb-c to death but "occasional incompatibility with cheap cables" is a bit misleading.

There is frustratingly little relation between price and quality. I have literally spent hundreds of dollars on usb-c-cables and I haven't even attempted to do displayport or thunderbolt through one, and I still don't own any that I'd expect to work on a lot of scenarios.


If price isn’t a primary consideration, get a Thunderbolt 4 cable and be confident it will work everywhere, particularly if it’s an active TB4 cable:


It's awesome being able to plop down on the couch and plug my laptop into a Nintendo Switch charger, that I also use to chargey phone. Charging a laptop before USB-C was an ordeal because I only had one specialised charger with a proprietary plug. Now I have half a dozen spread around the house and car.


Funny that you mention Nintendo Switch, because Nintendo made a non-standard implementation of usb-c there and connecting console to the standard compliant cable and charger can brick or fry the console. Perfect example of USB-Confusion :)


Between the proprietary plugs and USB-C, we had the dark ages of micro-USB which somehow always came loose after a few weeks of use




In an initial flurry of enthusiasm I bought a bunch of high-quality cables and I'm very glad I did. I can keep duplicate cables around in certain pockets etc. and I know I can always connect stuff. I had always used default supplier cables and these fancy ones feel much better in daily usage.


Won't you still need rare cables in case you need them (idk, a usb-b cable for instance...), and couldn't you already throw away whatever cable you wanted and buy some more as it pleases you ? What I mean is, the previous situation also little issues if you were willing to throw money at it, as you seem to be doing now.

Even as beard shavers and display monitors have come to support USB-C, I still don't see how people can get rid of their A->C cables, or not keep around lower standard 3m long cables because thunderbolts ones aren't sold in these length, or still need a cable for their camera etc.


I switched to usb-c as much as I could. I recently travelled for a month with all my battery-powered work and personal stuff (2 MacBooks (one Intel and one M1), 2 iPhones, Nintendo Switch, game controller, mouse (that one is micro usb), headphones and shaver). I brought only the following as a trial: 1 Anker 45W GaN charger[1], 1 30cm usb-c lightning cable, 1 1m usb-c cable, 1 usb-A to C adapter, 1 usb-C to A adapter which went unused, and 1 usb-c to micro adapter.

It went better than I expected. Sometimes I used the A-C adapter to trickle charge stuff in the hotel when I was out, taking my own charger with me for the day, and other than that just rotating what I was charging. The 45W charger is not much bigger than an OG iPhone charger and had no problem with my 16” MacBook. The difference in charging time to the Apple 87W charger wasn’t noticed.

One bonus I did not anticipate. You know how some cheap devices have usb-c charging that only seems to work with a USB-A to C cable? The adapters I mentioned can work around that.

One thing want to do but not tried yet is convert a few micro-usb things to usb-c. You can get convenient little breakout boards for it on Aliexpress.



I have a similar packaging when traveling, except with two chargers instead of one (macbook’s fast charger and one for the rest of the divices). For comparison, before USB-C I needed the Macbook magsafe charger, two USB-A to lightning cables and a 4 or 5 USB-A to micro USB cables for the appliances. When the Switch arrived it shared the USB-C charger of the 16” macbook when traveling.

Basically I feel the type of cables changed but I am not traveling much lighter not has it become that easier on managing stuff. I still think USB-C is fine, better than micro USB on so many respects, I just don’t feel the revolutionary aspect yet.

Perhaps we’ll be there in 5 years? If we din’t end up with new fragmentation on the wireless charging part.


Replace throwing away with putting in box if you like. There's less need for those cables, because there are fewer devices that need them. But you gotta work on that, I also have a bunch those magnetic cables, so it's either USB-C or device with a magnetic adapter plugged into it with a cable.


this is the solution, the only problem is that it requires you to spend money (the full-featured USB-C cables are expensive) and throw things out, two things most people hate doing.




This is an incredibly thorough analysis of all the different kinds of things that can appear on the end of the USB-C. However, I think it puts blame on the hardware spec, when in reality the drivers are at fault. It is up to the driver to sort out the mess of options and provide feedback, however, engineers are not known for UX. All of the tools are there for querying caps, but this information simply doesn't propagate upstream to the GUI, so the user is left scratching their heads when they don't get bandwidth or connectivity. Recently I have started seeing devices alert me when they are plugged into a sub-optimal hub (e.g., Salae's USB-3 logic analyzer), but I think it will take some time for the driver/application space to catch up.


Plugging the cable in is the last thing you do with the cable, after buying/searching for/selecting between cables. Maybe you brought the cable with you on a trip or to the office or whatever.

If it takes you until the last step to realize you don't have a cable you can use, that's a huge spec UX failure.


Yes and, in contrast, the connectors for cables inside desktop computers are mostly distinct and difficult to plug into the wrong ports.


Happenend to me. Bought cable, bought car power adapter for usb-c. Bought adapter to Plug USB-C into USB-A of the car adapter. Plugged everything together. Phone is not charging, for whatever reason.


Even if the cables were marketed easier, you still want to see info pop up if you have the wrong one.


I blame the spec because if people commonly use what you designed the wrong way, you did not design it correctly.


That statement seems to lack consistency. You blame the spec, and then blame the designer. Which is it?

EDIT: I worked t intel, the specification is written by the architects and the implementation is created by the designers. Two distinct groups of people.


By designers I believe they mean the authors of the spec.

So unclear spec = implementations aren't as consistent as the authors of the spec were hoping for.


I took it to mean the spec’s design.


This is still a problem :

> Finally, the USB Battery Charging spec enables a weirdly missing feature: a device plugged into a battery pack had no standard USB command it could issue that simply asked, “How much current can I draw?” Instead, different manufacturers came up with solutions that were not always compatible, limiting charging among certain devices.

It's not a proper power delivery standard until this issue is dealt with.

(Note that this also applies to other unreliable power sources.) Heck, even to the main house power : you can only draw 240W so many times before you trigger the circuit breaker...


>this information simply doesn't propagate upstream to the GUI

Windows has done this since at least XP for various combinations of USB 1.1 vs 2.0.[1][2] I don't know whether the same is true for USB 3 though.




Honestly, it can also be the fault of the spec. There is such a thing as a spec being too broad or too under-constrained and allowing too much rope for implementers to hang themselves with.


I wish there was a consumer-accessible tool that I could plug a USB-C cable in and it could tell me its capabilities. (I remember in the not-so-early days when Benson Leung, a Google Chromebook engineer, would on his own time buy and test cables on amazon and rate them. Some were actually dangerous and could fry your equipment!)

Is it a "charge-only" cable that can only do USB2 speeds? How much power can it transport (if there's no id chip in the cable, perhaps this can be deduced by measuring the voltage droop when requesting various power modes over USB-PD)? Can it carry DisplayPort-over-Alternate Mode? -over-Thunderbolt? etc.

Last I checked, 6 months ago, it seemed there was only lab-scale equipment that could do this.


I dealt with USB-C hell when I was setting up my new office. BYO (choose your own) laptops meant that the USB-C ports on each employee's laptop had different capabilities (alt mode for DP 2-lanes? 4-lanes? HDMI? etc...) and the same for monitors and docks. I got about half way through designing this device (PCBs went out, firmware never written), intending it mostly for identifying sources and sinks before I had largely solved the office's problems and my needs faded.

If there's collective interest, I could get back at it to finish the job.


There are already type-c testers that can monitor and dump the PD communication, so you can look at PDOs and Alt-DP VDOs to see what each side supports and what is negotiated. No need to re-invent the wheel.


As (according to the article) all of these cables carry little chips broadcasting the standards they support – couldn't this be just some little software app which just reads out that cable info?


The article is actually wrong on that point: many USB-C cables do not have any chip, only the ones which have extra capabilities (like being able to carry 5A of current instead of only 3A) need to have a chip.


I think you misread the article. It consistent refers to the connector on the cables as "cable end", and the places you plug these cable ends into as "ports". It says that the ports are the ones that broadcast the capabilities.


Tangentially, I've had great mileage out of the Satechi USB-C power-meter [1], which has demonstrated how cheap Amazon usb-c cables really don't carry as much power as Apple's expensive ones

[1] Out of stock, but I'm sure there are others on the market:


Similarly I like my Witrn Qway U2 which does power meter but also gives you the ability to check which fast charge protocols are supported, and for USB-PD and QC3.0, the supported voltages and watts. You can even trigger them manually though I've broken some devices with this before.


I was going to recommend this too! It feels high quality and has a nice, bright display as well.




Linus media group will in the near future


This seems like the place to ask, what is up with USBC displayport alt mode during boot/bios?

Like I'm traveling with a usbc only monitor connected to a 6800xt and everything has been working fine with it until yesterday.

I updated manjaro packages and the kernel to 5.15, and somehow that resulted in the monitor not working during boot anymore. Which I just don't understand the logistics of AT ALL. How does the host OS relate to video out during boot?

The video out also didn't work once booted into linux but I was able to resolve this by replugging the monitor a couple of times after each restart. Ultimately reverting back to the 5.14 kernel fixed it in Linux but didn't fix it during boot.

So now I just have to enter my LUKS pass blindly and hope for the best or that I never need to adjust my bios settings ever again.

And on a slightly related side tangent how do people who switch to a bluetooth mouse/keyboard adjust their boot/bios? They just don't?


One nice thing about Apple computers is that Bluetooth works before the OS is booted.

I’ve heard some motherboards with built in wifi can enter the bios using a long power button press or something, and pair from inside the bios. Some Bluetooth adapters can stay paired after a soft reboot too. Both of above I only know about from seeing people complain online that these features don’t work.

There are some usb Bluetooth adapters that let you pair directly from the adapter to a keyboard, no OS required once it’s set up. Some keyboards have an optional usb cable you can use. You can also use a keyboard with a proprietary usb wireless adapter, that is a normal usb HID device. All Logitech keyboards come with this even if they support bluetooth, probably because tech support is a nightmare otherwise. Amusingly, Logitech Bluetooth devices sold for macs are the same products but simply leave out this adapter.

Come to think of it, I use normal bluetooth devices with a windows desktop and at least once a month I need to connect a usb mouse to turn Bluetooth back on (it’s easy to turn off by mistake) or because things just stop working.


You have to rustle up a wired keyboard, at least. Fortunately, most hotels and motels will have them handy in their computer rooms, and almost any business will have a keyboard for you to try borrowing.

I've been carrying my full sized wired keyboard along with my laptop since I had a laptop keyboard fail a few devices ago. I'd rather have a portable pc and monitor in a clunky case, the form factor of a laptop has always seemed the wrong solution for the problem being solved. Multiple pieces isn't a big deal.


> how do people who switch to a bluetooth mouse/keyboard adjust their boot/bios?

Most wireless mouse/keyboard use the same USB HID drivers as the wired equivalents. So they work just fine in the BIOS/EFI. At least that’s been the case for every device I’ve used; I’m sure there are exceptions.

That aside, fuck Bluetooth keyboards/mice. Even if you don’t play games, Bluetooth latency is very noticeable. I much prefer logitech lightspeed mice.


Wireless keyboards that come with a USB adapter will work, but ones that connect to the computer’s Bluetooth usually do not.


Ahh I hadn’t even considered using the built in Bluetooth since pairing random devices is so hit and miss. It’s one of those things that always breaks at the worst possible moment.


I think USB-C solved some problems (no need to keep numerous different cables) but created another one - everything is now USB-C, and you can easily fry your things. My case: I lost the charger for T480 and purchased another one, not original from Lenovo, but something cheaper. I thought: the same specs, why should I pay 2-3x more. After two charges and a third attempted one, white smoke and smell of burned component. Motherboard replacement cost me almost 10x more of that original Lenovo charger.

After this, I don't touch third-party USB-C cables unless they charge something I don't care about.


Why is that a "usb c problem" as opposed to "cheap 3rd party charger problem"?

I buy a lot of 3rd party chargers myself, but frying electronics with a bad cheap charger has existed long before usb c.

(my personal life now with usb c is better... I buy a couple of quality chargers and cables and I'm good for everything. My Lenovo adapter can charge my phone in a pinch that's amazing! :)


Because of the purported interoperability explicitly implied by the U in USB, and what people have come to expect that stands for, AND the fact that the specs spell out charging protocols, voltage restrictions/limiting, etc, backwards and upside down. It's a bit like a sort of "good" inverse of DRM: that specific charger's failure doesn't fall into a grey area, it squarely calls it out as bad, because "you get a certification" is gated on a manufacturer's word that they've implemented the spec, and correctly. (DRM, by comparison, implements a "thou shall not pass" that is sufficiently complex that passage incontrovertibly equates to breakage. Here, the "thou shall pass" is tied to some complexity that the manufacturer clearly promised they implemented, but didn't.)

I expect the GP could reasonably report where they got the charger to the USB-IF, and theoretically cause the manufacturer in question to receive a bit of heat for what occurred. Practically speaking the state of things suggests that the USB-IF is probably dealing with enough of a firehose of such reports it probably takes sufficiently long for action to be taken that manufacturers practically get away with this sort of thing :'(

Obviously if the charger was purchased from somewhere like Amazon it'd probably never get taken down without reasonable expense (purchasing additional units to prove danger) and media fanfare. Hahah.


How is "purported interoperability" important here though? There were big news warning of highly proprietary cheap Apple chargers frying MacBooks as well. You're trying to blame USB-C for a problem that's completely orthogonal to it.


But then again, you can now buy one (or more) "expensive" brand-name USB-C cables that will pretty much work with everything. The expensive Lenovo charger and cable will probably not fry the cheap junk you may have lying around. And it's still a win, you don't have to carry / find that one particular cable.


This is a lovely illustration of the problems with USB-C.

Anyone who thinks USB-C is better than the earlier variants has Stockholm Syndrome.


Just yesterday, I was telling myself I had been a fool to spend more money on yet more cable-ware, when I am surrounded by cables I don't need.

But now I feel a lot better, thanks.

Charging cables are set up in a couple of places in the house, aren't used for data. My dealer for charging cables is Rolling Square. They are nicely built and have complicated adapters on the ends that can handle all the USB-PD stuff, up to 100 Watts:

Data-wise, they are just like Apple's charging cables: USB 2, 480 Mbit.

For data, I go with OWC Thunderbolt 4 cables. My two-meter cable should arrive tomorrow.

I feel like there should be a 12-Step program for this.


I guess the issue is that one type of cable is more expensive than the other? Otherwise I would prefer to have cables that can simply do everything.


Yes, the TB4 cables are more expensive than the ones intended for just charging. And the charging cables are designed to provide power to a range of USB devices, most of which were designed before USB-C Power Delivery was a thing.

The charging cables have adapters on each end that can do USB-C Power Delivery, micro-USB with (I believe) "fast" charging per the Qualcomm or Samsung specs, or Apple Lightning.

But yes, they don't have the re-timers necessary for 40 Gbit data.

The Thunderbolt 4 cables cost about $50 right now (2 meters), about twice the price as the universal charging cables.

All of these cables have E-Marker controllers at each end to negotiate all of these modes. I was able to find the data sheet for a common charger controller, made by Cirrus Semiconductor. It's a little ARM Cortex M0 computer.

So a wired local area network of computers talk amongst themselves to figure out how to push energy and data around.

Rolling Square was pricing their stuff at deep discount for Black Friday, a good value. Kickstarter products, they've been around for at least five years but might be clearing inventory before the new year.

OWC, I think I was buying SCSI terminators from them back when the rubble of the Berlin Wall was still on the ground...

One last thing FWIW --

For my travel bag, Rolling Square has a super short version that can fit in your pocket. One of those, a Thunderbolt cable, and a quality USB-PD charger can handle just about any situation.

Crazy times.


I must admit I find it very depressing.

I also bought a new desktop PC last week and already misplaced the manual. It seems it has several USB-C type plugs, but they are also not all the same. How will I ever be able to remember which is which?


I spent a lot more time on that website than I expected to.

Thank you for the heads up.


I want a device where you plug both ends of a USB C cable in, and it reads out max data throughput + how much power it can push.


Lab grade devices (like products from totalphase) that can do that properly are usually very expensive (like $20k). But there are some cheap boards around that might work (no guarantee):


Thanks for the link! I wish they shipped to Europe though.


Maybe I’m lucky, but I have only ever had 1 problem with USB C, and it was a really minor case[0]. I just keep getting anker cables when I need them, and it always works. I keep reading about these spec issues, but I haven’t had any issues myself (aside from the one I listed).

0 - My double wide qi charger has a USB C socket, but came with a USB A brick and an A to C cable. That works fine, but when I plug it into my kitchen receptacle with built in USB C, it doesn’t work. I ended up moving that to another room for unrelated reasons, so not a big deal either way.


Fun fact: the USB4 20Gbps mode is not the same as the USB 3.2 Gen 2x2 20Gbps mode! That means there are 3 different 20Gbps cables if you include TB3.


I included only a partial list, as I feared if I listed all possible configurations, including wattage limits, it might be 60 items long!


>USB 4 basically implements Thunderbolt 3 inside the USB spec, making it a requirement for all USB 4 controllers

That is not true. The support of Thunderbolt 3 is optional under USB4 spec. Along with a few other nitpick that is not entirely accurate. But it gets the point across

And its time to tell the unpopular story again. ( Because USB-C Supporters hate it )

Trying to help a lawyer out and trying to explain why the $5.00 USB-C cable he'd bought from Amazon wasn't delivering 4K video to his expensive monitor AND powering his laptop too.

Me: OK: so its a USB-C cable, but its not a high data rate USB-C cable.

Him: But, its a USB-C Cable.

Me: but, no, not all USB-C cables are high speed cables. And some of them can't do high speed and power delivery

Him: but... its a USB-C cable: it plugs into the port.

Me: Um... just because it plugs in, doesn't mean its going to work. You can have USB-C cables that are actually slower than the old USB ports.

Him: but.... shouldn't it just work?

And so on. For... 15? more minutes? maybe 30? I finally got him to buy a "proper" belkin USB-C cable .

This basically sums up everything that is wrong with Tech thinking vs User Thinking.


Author of the article here—please do tell me more about the Thunderbolt 3 and USB 4 relationship. I used “basically” to hand wave over some of the detail, but would love to know how to dig down on this further. (And I welcome nit picks. Seriously! We just did a couple tweaks. Some folks who buy HDDs said they see 3.0 Micro-B all the time, and that is absolutely true, so we modified a sentence about that.)

I'm leaning a bit on three things: • The USB-IF says that USB 4 is based on Thunderbolt 3 and incorporates Thunderbolt 3. If it's optional, they buried it in the spec? Would love to know where if you do so I can make that clearer. (See for instance.) • Apple’s USB 4/Thunderbolt 4 controller ostensibly incorporates all previous standards with backwards compatibility, so the question will likely arise in a specific case: a Thunderbolt 3 device with a Thunderbolt 3 controller attached to a USB 4 controller that isn’t a Thunderbolt 4 controller. In that case, the host computer’s USB 4 controller would have to negotiate down to 10 Gbps and USB 3.1 Gen 2? (???) • In practice, I wonder which controller modules major brands besides Apple will adopt: it seems most likely they would want USB4/TB4 not USB 4-only?

Per the above about the lawyer, too, the USB-C Charging Cable Apple offers (no video, 480 Mbps USB 2.0 data, and up to 100W power) is absolutely the most maddening cable on the market.


This will need some time to dig into spec to give you the definite answer ( As it was in Spec 1.0 and I dont think they have changed it since ) But if you trust wiki as a reliable source on it [1] under Thunderbolt 3 compatibility

>The USB4 specification states that a design goal is to "Retain compatibility with existing ecosystem of USB and Thunderbolt products." Compatibility with Thunderbolt 3 is required for USB4 hubs; it's optional for USB4 hosts and USB4 peripheral devices.[15] Compatible products need to implement 40 Gbit/s mode, at least 15 W of supplied power, and the different clock; implementers need to sign the license agreement and register a Vendor ID with Intel.[16]

i.e It is part of the USB4 spec, but it is not mandatory.

First thing is that we or at least I haven't found an answer from Intel on the cost of testing and licensing on Thunderbolt. ( So before anyone claiming Intel is greedy, some work has to be done to ensure QA, and work needs money, even if it is just registering an ID. ) Being Royalty free doesn't mean everything else is free. But let's assume it really is free.

Now in my pure logical guess and observation from the current market is that all USB4 host controller right now have at least Thunderbolt 3 compatibility because getting rid of it doesn't save much cost than provider another SKUs. And so far it seems all announced USB4 controller are also TB4 controller for the same reason. As TB4 isn't that much different to TB3.

>In practice, I wonder which controller modules major brands besides Apple will adopt: it seems most likely they would want USB4/TB4 not USB 4-only?

Yes, but that is assuming they cost the same and they dont start doing market differentiation / segmentation. Whether there is an market for cheaper USB4 controller remains to be seen. For example. You could have USB 4 host controller that only support USB4 20 Gbit/s Transport ( not the same as USB 3.2 (20 Gbit/s) ) and not support any Thunderbolt compatibility. Even if that is only a cost saving of possibly pennies I dont think we should underestimate the power of greed. And in fairness if you do millions of unit penny counting is important.

I hope, in pure good faith, that wont happen because it is easier to market existing USB 3 20Gbps and have all USB4 supporting both TB3 and TB4. But again this is not required by spec. And all it takes is a bad actor in the market to do it.

And in all fairness I dont think USB4 Host / or USB - Type C Host were the issue. I do think the consumer should know what the port they buy have support for. But USB-C cable is simply is a bag of hurt.



I found it in the spec in section 2.1.5. (Referring to the May 19, 2021, clean revision of USB4 1.0.)

"A USB4 host or USB4 peripheral device can optionally support interoperability with Thunderbolt 3 (TBT3) products. "A USB4 hub is required to support interoperability with Thunderbolt 3 products on all of its DFP . A USB4-Based Dock is required to support interoperability with Thunderbolt 3 products on its UFP in addition to all of its DFP. "When interoperating with a TBT3 product, Thunderbolt Alt Mode is established on the link between products. The USB Type-C Specification describes how a USB4 product negotiates and enters Thunderbolt Alt Mode."

So, accurate!

However, my question is about major brands. Will Lenovo, Dell, etc., go for USB 4-only instead of USB 4/TB 4? I guess we'll find out.

But my understanding would be that a Thunderbolt 4 controller connected by a USB 4 cable to a USB 4-only device running USB 4 for 20 Gbps would still work through Thunderbolt 4’s backwards compatibility across all USB modes.


I don't see that as a problem that can be solved. It's not like it's a new issue. The most direct equivalent is Ethernet cables. If you don't have the right category of cable for the speed and distance you're running, it's likely not going to work. Or it will work, but it will be slow due to packets constantly being retransmitted. Power cabling has a similar and more dangerous issue. Don't buy a cord with the correct wire gauge for your load and the length of the cord? That's a fire hazard.


Maybe USB-C cable and connectors could use two color codes. One for power delivery, one for data rate.


Useful article. I wish I could remember what the U in USB stood for. Maybe I don't want to know.


USB stands for Universal Serial Bus. The U stands for Universal.


In case it wasn’t clear, the GP’s comment was sarcasm, considering the messy combinations that make it sound anything except universal.


As in there's a universe of standards for USB-C!


I could have sworn they changed it to 'Uncertain Serial Bus'


According to HN it stands for Unusable.