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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)

#361

Post by Max-q »

tzs wrote: post #64
lesuorac wrote: post #13

I know everybody is still on the high from USB-C but I'm still going to go on the record it will be one of the biggest disasters in cable history. 1) There's going to be video-only cables; low-voltage only cables; etc and this time everything is usb-c so you can literally only tell which ables work by testing all of the dozen cables instead of the 1-2 USB-As you have. 2) The connector is symmetrical but the pins aren…

I wish there was a requirement that USB C cables must have sort of ID chip that can be easily read that tells what the cable supports, so that we could have simple testers that you can plug a cable into and be told what speed and power it supports.

USB C with USB 3 had an id chip. If the cable does not have a chip, it is good old USB 2.

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

#362

Post by levidos »

randyrand wrote: post #311
snakeyjake wrote: post #140

> Making USB reversible to begin with would have necessitated twice as many wires and twice as many circuits, and would have doubled the cost. This is... not correct. You can make USB reversible with 1 extra pin and 1 extra wire. Grounds on pins 1 and 5, data on pins 2 and 4, and VCC on pin 3. Then have those pins on both sides of the plug and a socket with a single set of contacts on one side. That's BASICALLY what…

To help visualize: 1: GND 2: DATA +/- 3: VCC 4: DATA +/- 5: GND

Can't that square metal be used as ground?

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

#364

Post by userbinator »

gzalo wrote: post #157
snakeyjake wrote: post #140

> Making USB reversible to begin with would have necessitated twice as many wires and twice as many circuits, and would have doubled the cost. This is... not correct. You can make USB reversible with 1 extra pin and 1 extra wire. Grounds on pins 1 and 5, data on pins 2 and 4, and VCC on pin 3. Then have those pins on both sides of the plug and a socket with a single set of contacts on one side. That's BASICALLY what…

> Then you implement auto crossover detection, dwhich had been around for years Mdi-x/auto crossover for ethernet was introduced in 1999, that is after USB (1996) was designed, not sure of the technique was known at that time

You can't do "auto crossover" with USB because it needs to distinguish between D+/D- for speed selection.

https://electronics.stackexchange.com/questions/73295/in-a-u...

It works for Ethernet because the transmit and receive lanes are separate, but with USB, there's only one pair used for both directions.

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

#365

Post by shiroiuma »

lxgr wrote: post #166
airstrike wrote: post #151

Earlier quoted context omitted.

The fact that the inventor doesn't see this obvious fact honestly boggles the mind.

Low-level (electrical/logical) protocol design and connector design seem like pretty different skills!

Did they not get a mechanical engineer to design the thing? And if not, why not? I wouldn't expect a mechanical engineer to know anything about electrical protocol design, so I wouldn't expect an electrical engineer or software engineer to know anything about designing a mechanical assembly (like a connector housing).

Some part of the design process here was managed very badly.

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

#366

Post by scarface_74 »

Max-q wrote: post #358
zlsa wrote: post #348

Earlier quoted context omitted.

4. Yes, all USB-C to USB-C cables can charge at a minimum of 60W which should be sufficient to charge almost anything 5. It depends, but the output capacity is printed on the power supply[0]. (Compare to USB-A, where the most you could do is 12W.) 6. The minimum of the cable (60W for any cable, 100W for some cables, 240W for a very few[1]) and the charger [0] Annoyingly, this problem is compounded when using a power…

4) A USB 2 cable with USB-C in both ends can't 60W.

And this is kind of the point, if HN commenters can’t figure this stuff out, what are the chances that normal people can?

Speaking of which, every time I ask the question about “tell me just from looking at a USB C cord…”, I learn something new.

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

#367

Post by shiroiuma »

northwest65 wrote: post #84
gsich wrote: post #72

Earlier quoted context omitted.

Logo up is no help when you try to do it in the dark.

You can feel it with the pad of your thumb.

No, you can't. I have a Microsoft USB mouse right here, and there's no logo anywhere on the USB plug.

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

#368

Post by sokoloff »

criddell wrote: post #333
sokoloff wrote: post #173

Earlier quoted context omitted.

I have many USB-C cables that don't behave like other USB-C cables. Just this past week, I had to buy another cable for my son's desk setup because of the many USB-C cables I had, I was out of the ones that would carry 4K video and USB-C 80+W PD to his laptop at the same time. (I had a couple that worked, but they were in use for my wife and I, and the couple handfuls of others I had were capable of zero or one of th…

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 to remember to come back and report on thread if I found one that works for all my devices (and what it worked for). It’s not something that I’ve time to carefully test during the week.

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

#370

Post by dweekly »

jonny_eh wrote: post #236
whoooooo123 wrote: post #190

Earlier quoted context omitted.

The problem with USB-a isn't that it's non reversible, it's that it's non-reversible _and_ rectangular, so it's not clear at a glance which way round it should go. All they had to do was make the connector have a non-symmetrical shape so that it's immediately obvious which way round it goes when you pick it up - you could do it without even looking. Think of how much time we'd have collectively saved with this minor…

For an example of an asymmetrical "rectangle", look at HDMI: https://en.wikipedia.org/wiki/HDMI#/media/File:HDMI_connecto...

DisplayPort is even simpler; a notched shaved off of one of the corners.
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