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Breaking down how USB4 goes where no USB standard has gone before
- sylware 4y agoThe hardware programing interface should not need to change (xHCI). This is a kind of test for the USB alliance to see how they resist planned obsolescence.
- spaghettiToy 4y agoI'm more interested in redundancy rather than more features (as a consumer). I've had to buy a new phone twice because the phones charing was finiky. Since you can't access the phones storage, this can be a death sentence to your data (and phone). From a embedded developers perspective, I want some analog pins. As companies remove the aux port from phones, we are losing the ability to send/recieve analog signals.
- Retr0id 4y agoThe spec allows for analog audio output, it just requires a multiplexer IC on the device-side. This is how passive USB-C to 3.5mm audio dongles work, but not all devices support it (since they either don't have the mux, or don't have a DAC, or the designers were lazy).
- spaghettiToy 4y ago>This is how passive USB-C to 3.5mm audio dongles work From what I've read, this isn't exactly reliable. Maybe we can blame the device IC, but it gives me Bluetooth vibes where everyone blames each other. Anyway, happy to see there is demand for it. I'll still be optimistic.
- Retr0id 4y agoIt's been perfectly reliable on the devices I've constructed. I suppose the main issue is the physical construction of the dongle itself - I've had reliability issues with 3.5mm cables for as long as I can remember, but I wouldn't exactly call disintegrating cables "bluetooth vibes".
- dont__panic 4y ago> Jeff Ravencraft, president and COO of USB-IF, told Ars that USB4's multi-monitor support depends on the computer "and is a question of how many streams a host can support, but "from a bandwidth perspective, the maximum is four 1K monitors at [a refresh rate of] 120 Hz, two 4K monitors at 120 Hz, and one 8K monitor at 30 Hz." Two 4k monitors at 120hz? Does anyone have experience getting that kind of resolution + refresh rate over a single TB4 cable? According to the bandwidth calculator I use, it is less than 40Gbps, but I guess color bitrate can bump it over if you're using an HDR monitor.
- eis 4y agoHm interesting that the quoted text argues in terms of bandwidth. A 4K resolution has 16x as many pixels as a 1K resolution. So if you can run two 4K monitors then shouldn't the bandwidth allow you to run 32 1k monitors at equal Hz? Same for the 2x 4K at 120Hz vs 8K at 30Hz. 8K is four times the pixels than 4K. At a fourth of the refresh rate, shouldn't it be also two 8K monitors? I am not very knowledgable when it comes to display protocols.
- Dunedan 4y agoI guess with "1K" they mean 1080p, because then it'd suddenly make sense. I'd be really curious who made the mistake of calling it "1K".
- eis 4y agoFHD has about 4x the amount of pixels than 1K. They'd be still off by a factor of two (32/4 = 8 vs 4).
- dang 4y agoSorry for the offtopicness, but I want to make sure you see these moderation comments from over a week ago, and this is the most recent post I can hang a reply on. The flamewar from 8 days ago was bad enough that this is still important, so please take a look: https://news.ycombinator.com/item?id=32724422 https://news.ycombinator.com/item?id=32724422 https://news.ycombinator.com/item?id=32724351 https://news.ycombinator.com/item?id=32724351
- wongarsu 4y agoAny bets how the naming scheme will develop after USB4 Version 2? Will we get USB4.1 Version 3, or USB4 Version 2x2? Or maybe something completely novel?
- bjt2n3904 4y agoSemantic Versioning? Nah. Use Evangellion Versioning. (Or Kingdom Hearts, if you prefer). USB IV.0+1.0 (ReBirth HD Final Remix)
- mortenjorck 4y ago> USB IV.0+1.0 You Can (Not) Use DisplayPort At 2160p60
- dktoao 4y agoThis madness needs to stop. What features does USB-C not have that the masses have been clamoring for? The only one I can think of is fixing the confusing sub specs that make different cables and ports incompatible with each other, which seems like it was a problem solved with earlier versions of USB.
- izacus 4y agoExternal GPUs and external docks with multiple monitors are ones that usually need Thunderbolt 3 type speeds which USB 4 standardizes now.
- t6jvcereio 4y agoYeah, let's stop improving.
- nathanaldensr 4y agoIf only recent USB specs were improvements...
- yccs27 4y agoStop trying to make new standards, start stabilizing on a definite version for now and get manufacturers to support it.
- matbatt38 4y agoYes, please do
- recursive 4y agoMore like, let's stop "improving".
- throw10920 4y ago"Adding features" is not synonymous with "improving". With the absolutely abysmal state of the USB specs right now, a more useful "improvement" would be the removal of little-used features, refactoring of the specs to make them easier to understand and implement, and completely redoing the naming scheme.
- happyopossum 4y agoMaking the logo program optional is just plain stupid. If a cable supports 40gb or 80gb but otherwise looks exactly the same, that’s just bad. Having s logo program to fix this, but not requiring it is even worse - it shows you see the problem but really don’t care about users enough to fix it.
- mortenjorck 4y agoIn practice, this will likely mean $30 Belkin cables have logos, while $10 cables from Amazon sellers with randomly-generated all-caps names do not.
- hedora 4y agoIf USB 2 and 3 are anything to go by, there will be even odds the non-logo cable works and the logo cable does not.
- dannyw 4y agoUSB has always eered to being as permissionless as possible.
- bergenty 4y agoIt’s a standard I don’t understand why they don’t pick the upper limit in the ranges for each thing and make it the standard. All these “options” mean it won’t be interchangeable.
- binkHN 4y agoI couldn't agree more. It just creates an unlimited amount of confusion. Here's a write-up about a Google engineer that bounced his head across numerous related issues as I couldn't readily find much of his content today: https://arstechnica.com/gadgets/2016/02/google-engineer-finds-usb-type-c-cable-thats-so-bad-it-fried-his-chromebook-pixel/ https://arstechnica.com/gadgets/2016/02/google-engineer-find...
- CoastalCoder 4y agoI have mixed feelings about this. The main problems I've had with HDMI and USB cables are (a) buying cables that I'm sure meet my requirements, and (b) trying to figure out if the cable is to blame when debugging poor results. If there's a trustworthy logo program, that should help. As long as retailers don't try to obscure the logo status of the products.
- jsmith45 4y agoUSB4 spec was really unusual for USB, because it was basically just defining the thunderbolt tunneling protocol, routing system, and connection manager (and its complexities), including the optional PCIe encapsulation, and notably one of the encapulated protocols that can be used is USB3.2. It also specifies the optional faster clock rates that TB3 used. A port featuring USB4 discovers and negotate using USB4 via a slightly modified version of the normal method for discovering TYPE-C alternate modes. If it is determined that the other endpoint does not support USB4, normal alternate mode negotiation will occur, including (if supported) the special analouge audio mode. For displayport alternate mode, the USB4 router becomes involved in supplying the connection. Finally, if neither USB4 nor any alternate mode is negotiated, then the port will use USB 3.2. I'm confused by the claim that USB4 does not support HDMI alternate mode. It is true that HDMI encapsulation is not supported, and that USB4 does not mandate supporting HDMI alternate mode (while it does mandate supporting DisplayPort alternate mode, since not all displayport capable TYPE-C peripherals are designed to handle the encapsulation), but a USB4 port can offer any additional alternate modes that the system designer wants. USB4 is also really weird in that you cannot really add additional ports to the system on via add-on cards or similar, since there needs to be one router for the whole host that is connected to all the USB4 ports, in order to implement the correct routing system, and also implement the guarentees like Display Port being available on USB4 ports, etc.
- rektide 4y agoAwesome details, super informative! Really interesting limitation you've mentioned about not being able to add in USB4. I hope this doesn't end up being true forever!! It's such an amazing set of capabilities; it'd suck to require them all to be built-in to the cpu/chipset. Couldn't a discrete video card (which has a DisplayPort output) implement USB4?
- jsmith45 4y agoTheoretically, yes a video card could implement USB4 (by having a USB 3.2 host controller, and a USB 2.0 host controller on board, implementing the routing fabric etc. But in so doing, you have limited the bandwidth available to the GPU (although they actually do still make framebuffer GPUs that don't have any calculation acceleration support). Also don't forget the need to support USB Power delivery (there is no requirement on being able to deliver power, but PD communication is required, and many USB4 devices will expect to be able to negotiate for some level of power delivery), so this card will probably need those extra power cables like normal accelerating GPUs use. But if you had such a card, and your motherboard has one two, then you have one machine that is actually two seperate USB4 hosts. This opens up a bunch of questions like does the host OS actually support this sort of configuration (especially if the Connection Manager is being implemented in software rather than hardware). Then you get weird stuff like being able to connect a Type C cable between the two hosts of the same system to get Host-To-Host Tunneling, but where both hosts are the same system. That is some wacky stuff. Even Host to Host tunneling is esoteric, basically allowing system that implements each host to pass each other arbitrary data over over the link. The example in the spec is exchanging IP packets, but I;m not sure that details of this usage are really standardized. It might also be possible to support add-on cards for USB4 by a routing chip manufacturer that makes use of the device to device communication features of of PCIe, to allow multiple USB4 routers to work together as a single virtual router. That sounds far more plausible, although doing that sort of thing would increase the contention on the PCIe bus.
- johnebgd 4y agoIt’s time to rebrand this as the Universally Confusing Brand (UCB). The people behind USB do not understand the damage they have done to the moniker.
- nonethewiser 4y agoSo how does this jive with the EU's USB-C mandate that takes effect in 2024? USB4 will be out before then. It seems like USB4 can work in USB-C plugs, so I suspect it will meet the law's mandate but I'm not sure. Something compliance teams will have to figure out before they can consider using USB4. Shouldn't be too much of a problem for large companies with these teams.
- sand500 4y agoUSB4 is a protocol which as a standard, requires the USB-C connector. The confusing thing is that just because you have a cable with a USB-C connectors on each end, you don't know for sure if it will support USB3.1 or USB4 or some other protocol.