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USB inventor explains why the connector was not designed to be reversible (2019)

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Re: USB inventor explains why the connector was not designed to be reversible (2019)

#461

Post by crote »

scarface_74 wrote: post #249
addicted wrote: post #35

Earlier quoted context omitted.

Maybe it’s news to iPhone people (and I say this as someone whose only used iPhones since he got a smartphone over a decade ago other than for 6 months where I used a Windows phone and 3 months of an Android phone), USB-C wasn’t invented with the iPhone 15. It’s been around a long time and most people have managed just fine, and absolutely loved the common cable. And everyone hated the iPhone user because you had to…

Grab a random USB C cable. Now answer a few questions. 1. What speed does the cable support? 2. How much data does the cable support? 3. Can it support video over USB-C?

These would be absolutely trivial to answer if the manufacturer followed the "cable logos" guidelines[0] - but pretty much every manufacturer conveniently seems to forget those.

[0]: https://www.usb.org/sites/default/files/usb-if_usb_type-c_ca...

Re: USB inventor explains why the connector was not designed to be reversible (2019)

#462

Post by barrkel »

postmodest wrote: post #178
aranchelk wrote: post #164

My take on USB-A: aside from audio connectors that have axial symmetry (and have no meaningful orientation), I never used any reversible computer cables prior to USB-C, and that’s not the main issue. Nor is it the axis of symmetry of the casing allowing failed upside down plugin attempts. The shitty part of USB-A is that the tactile feedback of being slightly misaligned is identical to it being upside down. My experi…

At least PS/2 cables were mostly made with "keyed" rubber jackets where one side was flat and the other rounded, so in the dark you could tell which way was up. (Though, that keyboard and mouse were different ports was stupid, so it loses points there)

PS/2 connectors were a regression on AT DIN & D sub 9-pin serial for most practical purposes.

The only upside of PS/2 was a higher mouse data rate, particularly with high monitor refresh rates, made mouse movement smoother. You didn't get this for free in Windows though, you needed a registry tweak to tell the mouse driver to bump the sample rate.

The huge downside was that PS/2 peripherals couldn't be inserted when the PC is turned on. They need to be inserted at boot time, and aren't detected if they're plugged in later.

And the keyboard and mouse connectors were physically the same but not generally switchable.

Re: USB inventor explains why the connector was not designed to be reversible (2019)

#463

Post by mmac_ »

JoblessWonder wrote: post #280
Scoundreller wrote: post #271

Earlier quoted context omitted.

oh god, I was made to be an idiot when I once told someone they would need a crossover cable to do what they wanted to do a few years ago...

If it makes you feel any better... for some reason there are some currently in production business jets that still require crossover cables for maintenance... so they ARE still required sometimes.

You encounter this in older industrial equipment. Some of the old ethernet chipsets don't support automatically switching the pairs around. It's not really a problem since at least in our local area they need to be installed by licensed cablers who are used to dealing with legacy devices.

Many devices won't get updated until chipsets go EOL or there's some other compelling reason to do so.

Having said that, modern chipsets seem to all support it.

Re: USB inventor explains why the connector was not designed to be reversible (2019)

#464

Post by crote »

mtmail wrote: post #116
devit wrote: post #81

If you have a reversible connector, then you might be entangled in a dilemma of which way is the "better" or "optimal" or "canonical" way, while with a non-reversible one there is only one way and thus no dilemma. And in fact USB-C is not really physically reversible, because the hardware detects which way it's plugged in and permutes the signals, as opposed to mirroring all the wires, so there is indeed a "right" wa…

> permutes the signals Does that cause a noticable difference, for example lower speeds?

No, there are dedicated high-speed "mux chips" for this[0]. You can get them with integrated redrivers to compensate for the inevitable signal quality degradation, if needed.

Once you get into the USB 4 range you're going to need all four lanes anyways, so you can just do the permutation in software.

[0]: https://www.ti.com/product/TUSB1142

Re: USB inventor explains why the connector was not designed to be reversible (2019)

#465

Post by rappr »

Max-q wrote: post #354
br0wnr1c3 wrote: post #294

Earlier quoted context omitted.

The new iPhone ships with a USB 2.0 cable, it does data transfer, just not at USB 3 speeds

I think the regular is USB 2 and the pro is USB 3

The cable is the same for both devices though

Re: USB inventor explains why the connector was not designed to be reversible (2019)

#466

Post by crote »

tommiegannert wrote: post #57
oniony wrote: post #10

Earlier quoted context omitted.

I think the problem these connectors have is that each ring has to slide over the other contacts to get to its correct location. USB Type-A has longer contacts for pins 1 and 4, the power pins, so they contact first and remain contacted before the data pins make contact. You can see that in this picture https://www.electroschematics.com/usb-how-things-work/ .

Many of the TRS connectors have a built-in switch to (originally) disconnect the internal speaker. It would probably have been easy to extend that concept to isolate all contacts until the tip hits the bottom.

That's not going to save you when you try to plug in the device-side connector with the computer-side already connected (and therefore already applying power to the cable).

Re: USB inventor explains why the connector was not designed to be reversible (2019)

#467

Post by criddell »

sokoloff wrote: post #368
criddell wrote: post #333

Earlier quoted context omitted.

What cable did you get? I’ve bought a bunch off Amazon and none work as well as the one cable I have that does work. I use a 4K + PD cable to connect my laptop to my monitor. The cable I have that came with the monitor works but I want a shorter cable. All of the ones I’ve bought cause the video to periodically cycle off and on.

I can’t find which of the old ones definitely worked (because I bought 6 at once and didn’t manage to return the duds) and though it arrived on Sat, I haven’t had time to fully test the new one. It carried 4K/60, but I haven’t tested it across all our devices to be sure it does full power delivery to all. (If it only works on some, I have no problems sending it back until I get one that works well for all.) I’ll try…

Thanks. So far I’ve ordered 3 cables and none work. The first one was a charging cable. I didn’t even know that was a thing and it’s when I started to learn about the differences between cables. My second one didn’t support DP Alt Mode which I seem to need. The third one was a 100W 4k USB Gen 3.1 that supported AltMode, but it just didn’t work reliable (that’s the one that results in the screen blacking out periodically.

I’m thinking I should just spend $70 for the Apple cable because it will probably work.

Re: USB inventor explains why the connector was not designed to be reversible (2019)

#468

Post by crote »

aidenn0 wrote: post #142

I still am more annoyed by it being the same width as an RJ-45 connector. Worse than not being able to plug it in is having it plug in and not work.

Even worse: male USB-C can fit inside female USB-A - and it is quite common for female USB-C ports to be placed right next to female USB-A ports.

I learned this the hard way - turns out your computer will just suddenly hard power off when you try to do this.

Re: USB inventor explains why the connector was not designed to be reversible (2019)

#469

Post by SergeAx »

There is a knowledge that you have to hold your USB cable with the logo upwards. Unfortunately, it is too arcane, so lots of cable and even device manufacturers just not aware of it. Also I it becomes quirky when the socket is vertically oriented.

Re: USB inventor explains why the connector was not designed to be reversible (2019)

#470

Post by Macha »

eternityforest wrote: post #431
kergonath wrote: post #407

Earlier quoted context omitted.

FireWire was great for that. I loved that connector.

Wasn't it based on the GB link cable?

No, they both used the same physical form factor, but it seems to have just been a model from a OEM used by both nintendo and apple around that time, rather than one spec deliberately copying the connector from the other.
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