Instead, USB device manufacturers want to cost optimize everything, which probably forced the standard to become so Byzantine. Understandable from a manufacturer's point of view, but terrible from an end user perspective.
In all seriousness though, the current state of a USB is ridiculous.
My wife innocently asked me why her USB C phone isn't triggering Android Auto in the car, and straight away you know it's because she bought a USB C power-only cable without knowing the difference.
Nice.
Less generally, these batteries can also break ground loops, which comes in handy when connecting a power supply to both a USB device and an attached analog audio device (e.g., iPhone and wired noise-canceling earbuds).
You'll note that many chargers started dropping handshaking because it was inconvenient. To be compatible with anything you need it, but there's many that don't ask, though they may only work with the equipment they were sold with. (E.g. defaults to 5V 2A charging.)
The historical design intent of USB is that, even when your laptop is in standby it still powers devices like your keyboard (so you can press keys to wake it up) and in exchange, devices promise to consume less than 2.5 milliamps (12.5 milliwatts) until they've negotiated permission to draw more from the host. After all, it'd suck if your laptop battery was going down noticeably even when the laptop was in standby.
Of course, loads of vendors of cheap devices ignore this - the makers of a $5 rechargeable bike light or USB fan aren't going to put in the components needed to negotiate charging speed. But in principle if you made a USB cable with only the power pins connected, compliant devices should only charge exceptionally slowly, if at all.
(Wall chargers, instead of enumerating as a USB host to negotiate power, used to put a certain value of resistor across the data lines, to signal what current the device could draw - this hasn't always been standardised, which is why phones and USB chargers can be incompatible)
Note also a fair number of laptops (read: every one I have used and checked) use PS/2 internally because it is interrupt driven and even lower power than USB. There are also plenty of laptops that advertise high current phone charging while off, some of which do negotiation, some of which don't.
[0] http://msdn.microsoft.com/en-us/library/windows/hardware/hh8...
Ignoring that, I'm not sure it's an improvement. Most of the power savings is having the keyboard initiate an interruptible event to wake the computer. Interpreting HID like in USB means the keyboard can't wake the computer, the computer needs to remain on to service USB interrupt endpoints.
The laptop I had with an always-on charging port actually charged things faster in standby, because that turned off the negotiation.
> defaults to 5V 2A charging
i don't think you understand how power transfer works.
voltage is applied (by the charger), and current is drawn (by the device that wants to charge). a charger cannot "dump power into" anything.
when chargers and devices attached to them engage in some sort of negotiation, that's not the device telling the charger what to do, that's the charger telling the device what its limitations are.
if you attempt to draw 3A from a device that can only do 2A, the voltage will drop outside of the specified range. to the extent that a charger can limit the charging current, it does so by dropping/cutting off the voltage until the current goes down. which isn't ideal for devices.
(perhaps you're confused by thinking that USB "chargers" are like battery chargers, and arbitrary USB devices somehow act like batteries. that's all wildly wrong.)
The main concern behind negotiation seems to be safety of the user and safety of the power supply. Detecting a safe load means detecting a not-short.
The basis for the 5V power negotiation on USB is extremely silly. The power supply is already current limited, protecting you from shorts, and the supply voltage is ~5V, quite far from anything dangerous.
This may be true for wall chargers but not devices capable of supplying power to peripherals while on battery power themselves.
For example, an external hard drive should not have to figure out that a large tablet can power it, while a phone won't, though trial and error, by attempting to spin up the disks multiple times.
Devices are going to misbehave anyway, it's probably more important to default to a reasonable level of mostly works.
Android already allows you to only use an USB connection for charging. Setting this as the default when you are in an unknown place sounds reasonable.
OTOH, a USB Y-cable physically has no data lines connected on the extra USB-A male connector; it thus provides a far stronger guarantee that there is no data travelling across them. (Not foolproof, but safer than a software-controlled switch.)
If you don't trust that cellphone won't transfer your private data via USB, I don't understand why you trust it not to do it via any wireless connection.
They're pretty nice too, the only made in Germany USB-C/lightning cables I have ever used.
Maybe it's possible to make one lacking both USB 2 and 3 data though, but I haven't seen one yet.
Nor have I seen a public USB-C outlet, for that matter, and I probably wouldn't be plugging my laptop or phone into one anyway: My own charger doesn't only protect me against bad intent, but also against cheap charging circuits that might or might not accidentally expose 220 Volt to my laptop's mainboard in case of faults.
Ouch. USB-C is even more fucked up than I thought… How does that even works with USB wall chargers?
> Nor have I seen a public USB-C outlet, for that matter
There are plenty of USB-A outlet everywhere (airport, trains, hotels, etc.), and most recent Android phones have only an USB-C port…
If they want to supply more than 5V/3A, they need to support the power delivery protocol too.
> There are plenty of USB-A outlet everywhere (airport, trains, hotels, etc.), and most recent Android phones have only an USB-C port…
Exactly: These are USB-A outlets. These are possible to implement using only a resistor network to announce the maximum charging current and always supply 5V, which is much easier to implement than variable voltage and the power delivery protocol. USB-C can do this too, but only up to 5V/3A.
USB-C devices are usually backwards compatible with all three of these when using an A-to-C cable or adapter: Legacy USB-A current identification via the D+/D- pins, USB-C resistor-based current identification via the configuration pins of USB-C and USB power delivery.
As Intel loses its raw CPU performance advantage, it's new marketing materials promote "features" and "convenience". Practically speaking, USB is defined by Intel, and it is making a visible choice to allow itself a position in the market for Thunderbolt 4 by making some USB4 features optional so they can include them in TB 4, and adding other small minimum performance guarantees and hoping that is enough to sell TB 4 chips to high-end AMD motherboard makers, which in turn makes their own CPUs (with built-in thunderbolt 4) more price competitive. It is a sound business plan, but not in the best interest of consumers.
The fate of a universal lingua franca connector is too important to be left to just one company. Why is it still being defined by Intel rather than a panel?
Intel, Microsoft, Apple and even HP are notable members.
The poor enforcement of trademarks being - that there should not be a plethora of things claiming to be USB which are not spec compliant, nor should people be using names like "USB 3.2 Gen 1x1" vs the marketing name "Superspeed USB".
You also see this poor enforcement with other organizations, such as DisplayPort vs DisplayLink.
This spills over to problems with cabling, such as how much wattage is supported for power delivery or what speed data transfer is available.
Oddly Intel is the one stepping up here with Thunderbolt 4, because it is now more of a certification than a specification.
Relying on cables internals for function is just as stupid as can be.
To be fair, there were only a handful of those really early on when M.2 was just getting started and OS/BIOS support for NVMe wasn't universal yet. And hardly any of them were released as retail products; they were mostly OEM-only drives. All of those drives went out of production 3-4 years before the first host devices that require NVMe and can't work with AHCI started to show up: USB to NVMe bridge chips for external enclosures. So if you haven't encountered an AHCI M.2 SSD yet, you probably never will and knowing about them is just an obscure historical curiosity.
- Host queries some property and each cable along the way appends their value to that message and passives it along.
- The endpoints either loopback if they're the new standard or pull down the pins if they're USB-2 only.
- It follows that if no message makes it back then we're limited to USB 2.0 and if a message does make it back, we can query/configure all elements along the path of connections. Right now this is impossible which makes it impossible to detect if there is a non 50v tolerant hubs between two hubs.
- The programming/hw implementation for PD and alternate mode would also be non-insane in this model. Currently PD requires stupidly complex state machines, op amps, resistor banks or some autonomous IC to pull off and there are so many screwups because it's such an obtuse standard.
- Supporting alternate modes, and providing more diagnostic information would be much easier.
There should have only been 2 passive cable types - 2.0+PD and USB 3 gen 1 - everything else should require a smart tag on the chip.
What does "CC" stand for?
There are an added pair of pins/single wire in USB-C cables that allow the devices to a) detect the orientation of the plug and b) do extended power negotiation for the increased power capabilities of USB-C.
This should all be solved at the negotiation layer, even if that needs to be made more complex, so that the remaining components can be simpler and reasonably-behaved.
Instead, we got something that allows each device to be a bit more electrically simple, at the cost of ballooning complexity for the ultimate use case.
USB-IF took their eye off the ball, and wrote a spec for manufacturers, without thinking about the consequences to consumers.
At some point, it's a value trade-off between {working product for use cases} and {+$2 on BoM}.
Not a criticism of the USBIF* just pointing out the motivations to underline your point.
* BTW I have plenty of criticism, this just happens not to be an example.
This outcome was pretty obvious, it's literally in the name of the damn thing: UNIVERSAL Serial Bus. The only way to achive that is to lower yourself to the lower common denominator.