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How many kinds of USB-C to USB-C cables are there?

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Re: How many kinds of USB-C to USB-C cables are there?

#101

Post by brandonmenc »

Ductapemaster wrote: post #36
manacit wrote: post #13

I've had a USB-C capable device (MBP) for a few years now, and it originally was extremely annoying. Needing dongles for _everything_ was annoying, and getting rid of Magsafe meant a lot of my existing chargers that I'd accumulated no longer worked. My work laptop (at the time) didn't use USB-C, so I had to keep two chargers around, and I couldn't charge my iPhone from my laptop at all. Fast forward a few years and I…

Out of curiosity, what USB-C dock do you have? I am in the market for one.

I have the OWC Thunderbolt 3 Dock and it also works perfectly.

https://www.owcdigital.com/products/thunderbolt-3-dock-14-po...

Re: How many kinds of USB-C to USB-C cables are there?

#102

Post by therein »

Godel_unicode wrote: post #91
jrochkind1 wrote: post #79

Earlier quoted context omitted.

Why don't they give NAMES to these different types of cables? They seem to have either no names or too many names where it's unclear what is intended for the consumer. Just giving the cable a clear name (in words, not icons), so you could know what you were buying, and a device could say "you need this kind of cable", and a person could write a blog saying "to support DP-Alt-Mode you need X kind of cable" and all use…

They did, kind of. USB2, USB3.1 gen 1, and USB 3.1 gen 2 are 480mbps, 5gbps/DP-alt-mode and 10gbps/DP-alt-mode, respectively. The problem is really that people won't remember that distinction unless they need to know it regularly, and unless you know to Google "difference between USB 3.1 gen 1 gen 2" you won't be able to figure it out.

I think the GP also meant more memorable names.

Re: How many kinds of USB-C to USB-C cables are there?

#103

Post by kllrnohj »

djsumdog wrote: post #64
mrb wrote: post #55

Earlier quoted context omitted.

« But is a 5Gbps cable enough? Or is a 10Gbps cable needed? » Here is the answer: if you need DisplayPort 1.0-1.2, a 5 Gbps cable is enough. If you need DP 1.3-1.4 (where they upped the transfer rate for higher resolution and fps,) you need a 10 Gbps cable. If you need DP 2.0 (I don't think products are out yet, the standard was finalized last month,) you will need a USB4 20 Gbps cable.

DP1.2a should be enough for 60Hz at UHD/2160p. 1.4 is needed for HDR support, 5K, higher refresh rates, etc.

DP 1.2a goes up to 21.60 Gbit/s, and 4k 60hz (which does work fine over 1.2a) needs 12.54 Gbit/s. I'm not sure how the 5Gbit/s and 10Gbit/s USB-C cables fit into this. It's obviously not just based on the cable's "rated" bandwidth, as if it was neither the 5Gbit/s nor 10Gbit/s connection would work at all for display. But it does, so it must not be, so what is it?

Is it 5Gbit/s per twisted pair? That would make sense as displayport uses 4 pairs so 4 * 5 comfortably gets you the 12.54 with plenty left over for regular data. But then it would matter for the 10gbit/s cables if it's talking about superspeed 1x2 (2x5gbit/s) or 2x1 (1x10gbit/s).

Re: How many kinds of USB-C to USB-C cables are there?

#104

Post by Dylan16807 »

jasomill wrote: post #84
AnIdiotOnTheNet wrote: post #17

Earlier quoted context omitted.

You ever wonder what the purpose of keying connectors is? I'm curious, because it's one of those time-tested ways to ensure that things get plugged into the correct ports and avoid costly accidents. Really simple too. Why on earth is a standard as ridiculously complicated as USB-C a better idea? What is the practical value of an "everything" connector when its spec is so complicated that it really doesn't support "ev…

Unfortunately, using identical connectors for incompatible protocols — often hazardously incompatible (to equipment) protocols — is an equally time-tested industry tradition, and not only in more cost-conscious market segments. High-voltage differential SCSI comes immediately to mind — one might imagine there'd have been enough margin and price inelasticity in the market for $200 cables used to connect rooms full of…

> identical connectors for incompatible protocols — often hazardously incompatible (to equipment) protocols

The main actual hazard with USB-C is that somebody solders the low voltage power pins backwards. What that has happened, it could happen to absolutely any type of cable, so it's not exactly a problem with the standard.

Re: How many kinds of USB-C to USB-C cables are there?

#105

Post by Dylan16807 »

AnIdiotOnTheNet wrote: post #44
derekp7 wrote: post #40

Earlier quoted context omitted.

For low volume production items, the plastics are more costly to design than the electronics. Therefore laptop docking stations are expensive to manufacture, especially as they are in use by only a subset of users. By converting to a docking station that requires a simple small plug for everything, that makes them much cheaper. Instead of making a huge chunk of plastic that the laptop has to click into.

That explains why laptops should have a standardized "docking station" port, not why that port needs to also support literally everything that runs on electricity with the ability to also channel high-current power in both directions.

What's your threshold for "high-current"? USB ports have been delivering about two amps for a decade, and most USB laptop chargers cap at three amps. Even the absolute max of five isn't much higher.

Re: How many kinds of USB-C to USB-C cables are there?

#106

Post by azernik »

derefr wrote: post #57
starsinspace wrote: post #42

After buying a screen which has only a USB-C DP-Alt-Mode input, I was recently in the market for a matching cable. My only requirements were “it should be as long as possible, at least 2 meters” and “it needs to support DP-Alt-Mode”. Now I thought this would be easy, just ask Google what kind of cable I need, right...? Well... no. Not at all. I wasn’t able to find any information whatsoever what kind of USB-C cable i…

The answer is supposed to be easy; it's "you need to buy one of those really expensive USB-C Thunderbolt 3 cables, because those cables—the ones that do everything—are supposed to be the only type of USB-C cables." USB-C cables are supposed to be universal, i.e. have all the features, all the time; and thus, USB-C cables should (in 2019) be very expensive. Any USB-C cable that isn't very expensive (in 2019) isn't fol…

> isn't following the standard

This is just plain wrong.

The USB standard explicitly allows cables that have a USB-C connector and don't support any USB features above USB 2.0.

Re: How many kinds of USB-C to USB-C cables are there?

#107

Post by Dylan16807 »

AdrianB1 wrote: post #56
wmf wrote: post #6

Earlier quoted context omitted.

This is used for charging laptops. Personally, I love having a single cable for power, USB, and DisplayPort.

Most laptop chargers are 65W, some are 95W, I haven't seen one over 100W. USB-C Power Delivery can do 100W (20V, 5A). More than 100W for the 1 in a million user is not the target of USB consortium.

Gaming laptop chargers often approach 200 watts. So it's uncommon but a lot more than one in a million.

Re: How many kinds of USB-C to USB-C cables are there?

#108

Post by virtualwhys »

starsinspace wrote: post #42

After buying a screen which has only a USB-C DP-Alt-Mode input, I was recently in the market for a matching cable. My only requirements were “it should be as long as possible, at least 2 meters” and “it needs to support DP-Alt-Mode”. Now I thought this would be easy, just ask Google what kind of cable I need, right...? Well... no. Not at all. I wasn’t able to find any information whatsoever what kind of USB-C cable i…

> After buying a screen which has only a USB-C DP-Alt-Mode input

OT, but what screen did you buy? I'm in the market as well for a USB-C powered travel monitor and was about to head down the what-cable-works rabbit hole.

Re: How many kinds of USB-C to USB-C cables are there?

#109

Post by basilgohar »

mmastrac wrote: post #46

There's always pain after a USB spec gets released. This has been pretty much par since USB 1.0 - switch chips were flaky back then, USB drives were quirky and getting them working on anything other than a specific version of Windows was a crapshoot, etc. Eventually all-in-one chips get less buggy, cable manufacturing gets cheaper and we move on to the next spec level and repeat.

Yes, and I'm looking forward to USB-C ubiquity in the near future, but these are definitely signs that this rollout could have used some more thought put into it. I'm for "USB-C all the things" but I have sympathy for the gripes about knowing what to use when.

Re: How many kinds of USB-C to USB-C cables are there?

#110

Post by deepsun »

Godel_unicode wrote: post #91
jrochkind1 wrote: post #79

Earlier quoted context omitted.

Why don't they give NAMES to these different types of cables? They seem to have either no names or too many names where it's unclear what is intended for the consumer. Just giving the cable a clear name (in words, not icons), so you could know what you were buying, and a device could say "you need this kind of cable", and a person could write a blog saying "to support DP-Alt-Mode you need X kind of cable" and all use…

They did, kind of. USB2, USB3.1 gen 1, and USB 3.1 gen 2 are 480mbps, 5gbps/DP-alt-mode and 10gbps/DP-alt-mode, respectively. The problem is really that people won't remember that distinction unless they need to know it regularly, and unless you know to Google "difference between USB 3.1 gen 1 gen 2" you won't be able to figure it out.

Would be easier to rename "USB 3.1 gen 2" -> "USB 3.2".

And the latter two would be "USB 3.3", "USB 3.4", problem solved :)

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