Live data from Hacker News

USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

anandtech.com

121–130 of 279 posts

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#121
post #3

Ars Technica just wrote an article about the confusing names of USB versions https://arstechnica.com/gadgets/2019/02/usb-3-2-is-going-to-... and now they have another one about this name. https://arstechnica.com/gadgets/2019/03/thunderbolt-3-become...

This is almost as bad as SpaceX's rocket naming scheme: https://external-preview.redd.it/yQJH1H8y7ypKanxgZKwIaJom5h4...

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#122
post #18

Earlier quoted context omitted.

I'm no means an expert but up to USB 2.0 there were 4 pins (2 for power and 2 differential signals for bidirectional data) With USB 3.0 they added 4 more signals for separate transmit/receive. Initially they used 8b/10b encoding and then switched to 128b/132b encoding. They also increased the signaling rate with each generation. Also in the USB 2.0 and earlier the higher level protocols were kind of inefficient with…

> With USB 3.0 they added 4 more signals for separate transmit/receive So is it not actually serial any more?

It's a low-speed differential pair that negotiates the initial communication. Once the bus knows it can go to a faster speed, it will switch to a separate receive differential pair and transmit differential pair.

    -Power
    -Ground
    -Signal Ground
    -USB2 data+
    -USB2 data-
    -USB3 RX+
    -USB3 RX-
    -USB3 TX+
    -USB3 TX-
So it's a slow serial bus that negotiates traffic onto a faster serial bus.

https://en.wikipedia.org/wiki/USB_3.0#Pinouts

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#123
post #86

Earlier quoted context omitted.

I feel like hand-wringing around that is a bit overexaggerated - at the end of the day the differences really matter for only really tiny subset of devices that need those 10GBit+ transfers and in that case you can guide yourself by the "SuperSpeed 10Gbit" "Superspeed 20Gbit" logos on the actual box. For everything else the protocols are forward and backward compatible, so you just plug in the cable and it works.

So remind me, why can you walk into any apple store, pick up a new MacBook and a 5K LG monitor, and when you plug in the monitor using the USB-C cable that was bundled with the MacBook it just won't work at all? My point is - the standards might be back and forward compatible. But the cables and ports definitely aren't - and your average consumer has absolutely no way of knowing. They look absolutely identical on the…

I had this happen to me once with an HDMI cable I bought for my monitor, which I thought was defective until I found out that it worked on my TV. It was then that I remembered that HDMI has several speed grades, and my monitor happened to have a high enough resolution that not all HDMI cables would work with it. Happily, the HDMI cable I had been using on my TV worked on the monitor, so I just swapped the cables and all was fine. So this issue is not exclusive to USB.

In fact, with USB the situation should be better, since all cables except the slowest ones are supposed to have a built-in chip describing how fast they can go. So in the MacBook example, in theory it should be able to detect the issue, switch to a lower resolution, and present an on-screen warning telling you what happened and why.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#124
What's optional?

That's the most important thing to know is what's optional in the spec.

That could make it great or a major pain. I'm referring to how many features the specification defines as "optional" for manufactures and that the USB organization requires for logos.

This is why even USB-C is a nightmare. Consider a USB-C cable or device port. It could be charge only, data only, monitor support. There are even more permutations and sub-features. Oh, you wanted charging and found one that has it? Know how much power it enough or overkill? It could provide 15 watts, 100 watt, etc. Think you'll just google the specs page? Sure, they never miss providing any of these details or make any mistakes.

Whether USB4 means one thing with nothing optional (or at least a very small number of combinations), will probably determine how much you like it or get annoyed by it.

HP even made it worse with a laptop USB-C port that could technically be used for certain docking functionality but tried to fud-deny allowing it for marketing reasons.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#125

Earlier quoted context omitted.

So remind me, why can you walk into any apple store, pick up a new MacBook and a 5K LG monitor, and when you plug in the monitor using the USB-C cable that was bundled with the MacBook it just won't work at all? My point is - the standards might be back and forward compatible. But the cables and ports definitely aren't - and your average consumer has absolutely no way of knowing. They look absolutely identical on the…

The cables should have a ss or ss 10 or ss 20 label on them. The end devices should too I believe.

Apple cables and ports have no logos on them whatsoever. Just plain white/silver if metal.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#126

Earlier quoted context omitted.

I've seen them for sale on Amazon and elsewhere. I always thought they'd be neat to throw in a supplemental kit bag for a second display on the go. I think some of the smaller ones were even bus powered.

I've seen those usb 2.0 display adapters and I never used one but I heard that they had low refresh rates and/or low resolution, due to the 5 volt limits. I personally use a usb 2.0 NIC so that I can be packet capturing on multiple switch/vlan/ingress or egress at the same time.

Bus powered and decent res (not 4k), but very workable for writing code a casual web browsing. I put a comment about my experience with one above.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#127

Earlier quoted context omitted.

So remind me, why can you walk into any apple store, pick up a new MacBook and a 5K LG monitor, and when you plug in the monitor using the USB-C cable that was bundled with the MacBook it just won't work at all? My point is - the standards might be back and forward compatible. But the cables and ports definitely aren't - and your average consumer has absolutely no way of knowing. They look absolutely identical on the…

This absolutely does need to be way more clear. There should be distinct and visibly obvious branding from the standards group. I should be able to tell by looking at a connector: * If it's claiming to be a certified cable/device or not. * The USB standard it conforms to (version) * The speed of data transfer it supports * The maximum wattage it supports * The maximum voltage it supports * (the connector type, but th…

Why is that? You can't do that from looking at a file with an unknown extension.

Physical connector technology and signaling protocol are entirely different things. I'd be fine with literally everything using the same physical connector, but knowing that I can't and shouldn't plug my 5VDC battery-charger into a 110VAC outlet.

I still have speakers that are connected by stripping a lampcord pair with my teeth, pushing a little button, jamming bare copper strands into a hole, and releasing a little button. I think you're asking for too much. Everything using one reversible connector that almost always guarantees 5VDC in a fallback mode is better than what we have today.

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#128
post #29

As someone who knows next to nothing about how USB actually works and just uses it, what goes into making each USB generation faster? At the physical layer, is it the materials in the cables are getting better? Or new ways of using the same materials? At the protocol layer, is it newly developed computer science theory being applied or is it just old fashioned pragmatic engineering iteration, looking at usage and mak…

> At the physical layer, is it the materials in the cables are getting better? Yes, and more expensive on that. Laptop makers totally hate usb 3.0+ for that. The industry standard for internal digital connectivity was the FPC - flexible printed circuit board, a very economical and ergonomic solution, but then came USB 3.0. Regular polyimide FPC can't reliably handle the high frequency signalling. Still, many laptop m…

Thanks for sharing and interesting industry perspective.

Color me unconvinced on one point though:

> Only very recently, there came an FPC maker that makes custom cabling with some proprietary dielectric that can handle 3.0.

A brief glance at IPC-4203A (which has been around since 2013) tells me this is a consequence of market cost sensitivity, not one driven by the inherent performance limitations of available material.

The latest IPC-4203B was just published circa March 2018 last year. Is there something new worth looking into here, or is this "recent advancement" just a manufacturing process-driven one which has made high-performance FPC more viable in the throwaway consumer electronics market?

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#129
post #86

Earlier quoted context omitted.

I feel like hand-wringing around that is a bit overexaggerated - at the end of the day the differences really matter for only really tiny subset of devices that need those 10GBit+ transfers and in that case you can guide yourself by the "SuperSpeed 10Gbit" "Superspeed 20Gbit" logos on the actual box. For everything else the protocols are forward and backward compatible, so you just plug in the cable and it works.

That sounds like '10Gbit ought to be more than enough for anybody' to me. Plus the good thing about USB is it just works, you don't have to worry about any tiny subset (well that's the theory anyway). I've had enough of my monitor, mouse, keyboard and printer all using different connectors thank you very much. Edit: Making make sense.

The issue is with USB-C you can run into limitations at the cable level where the cable is too long or poorly shielded to provide devices with the right data speeds/power requirements and some companies (cough apple cough though it's bleeding more into other places as the aesthetic gets copied) refuse to properly label things. And some of the differences are not spelled out anywhere, for example to get the top thunderbolt 3 data rate of 40Gb/s on a passive cord you cannot have a cord longer than .5m. To get a longer cable to pass the full speed (to drive say an eGPU or high res monitor) you have to get a more expensive active cable (that may not work because companies online are unscrupulous and will try to rip you off). All of this is extremely opaque to users who just want to have a slightly longer cable to arrange their desk as they prefer.

At least with the different connectors and cables I didn't have to worry so much and things generally worked when plugged into the right place.

[0] https://www.cnet.com/how-to/usb-type-c-thunderbolt-3-one-cab...

Re: USB4 Specification Announced: Adopting Thunderbolt 3 Protocol for 40 Gbps USB

#130
post #99

Earlier quoted context omitted.

pulling my MacBook Pro out of my backpack to look, it looks like they aren't fans of iconography to say what a port is capable of either. Can't remember if my old 2013 MBP had the icons or not, but my current one for sure doesn't.

All ports on Apple's laptops behave the same for charging - they'll continue to provide power while sleeping, but won't start providing power. If you want to use it as a battery in your backpack while it's closed you have to plug your phone in, wake the computer up, then put it back to sleep. At least that was the case last time I tested it. For the most part they don't need colors because all of the ports are the sa…

Wow, "only starts charging while awake" really explains some confusing mornings waking up to a dead laptop.
Post reply on HN