Quote:
Originally Posted by ratinox
USB Power Delivery (USB PD) makes this mess go away, assuming device manufacturers comply with the specs.
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But there are multiple specs. No-one is enforcing use of just one spec. Also the millions of devices out there.
Someone will add a new spec and there will also be USB PD 2.x
So no-one can make the mess go away.
Also USB-C isn't a single standard for non-power.
The existing devices also need to be supported, and not everything still on sale is USB-C
There is the separate issue of data speeds (USB 1.x to 3.x)
Signals (there are micro and mini that don't just do USB serial data, but analogue audio, stereo + composite video etc). USB C can be USB 1.x, 2.x or 3.x data, analogue audio, DP style digital video or ethernet, but only one at a time. Power signalling can be by extra dedicate power serial interface, or using the regular USB D- & D+ (which can be by serial data to charger, or sensing charger resistances or voltages).
The USB-A is usually a host, but sometimes on USB 3.0 there is A to A!
The USB-A has 4 connections or 9 if USB 3.x speeds are supported.
There are USB 3.x versions of micro-USB and USB-B sockets that allow original plugs or bigger USB 3.x plugs
Even Mini-USB as well as Micro-USB can have the USB-C reverse mode where the gadget client becomes a host and can supply power instead of charging the gadget. Some Micro-USB and some USB-C gadgets can become a host for data and still be a client for charging.
There are at least 5 kinds of client connector with Host USB-A < 3.x (1 pair + power), including USB-C with 4 wires.
At least four kinds of client connector with Host USB-A 3.x (9 wires): USB-B, micro-USB (both larger sockets compatible with older plugs), USB-C and crazy USB-A USB 3.x.
If you are lucky a USB-A socket has SS printed at it if USB-3.x, but you should be able to see the 5 extra connections in front of the original 4.
If you are lucky a USB-C socket might have DP printed on it, if the alternate digital video mode is supported, but your cable might not work.
The different alternate data modes of USB-C are mutually exclusive. It's stupid. The equipment should simply have an HDMI socket, or a mini one, not Alt DP. It should have a 3.5 mm jack for audio, not the Alt Analogue on USB C. A laptop or big tablet should have a dedicated power socket at 5, 12 or 20V. Easily could be three sizes. There should be an ethernet socket on laptops.
The idea of USB-C doing everything is stupid, then an insult to put only one socket even though is used for charging, data I/O, and video (and often can only do one of those at a time).
It's a mess and now nothing can fix it.
https://m.xkcd.com/927/
USB started being broken at the start because it was "only" for slow peripherals such as keyboard, mouse and joystick, but idiots used it instead of SCSI for scanners (too expensive and big), or instead of Firewire (too much royalty).
USB 3.0 needed more wires. The backward compatible USB-A, micro-USB and USB-B connectors made that a mess. Should not have been USB at all.
USB-C is the ultimate mess, trying to replace all the connectors, inc 3.5mm jack, USB-A, Ethernet RJ45 and DP/HDMI and dedicated power connections with one cable and one connector. Good luck on getting a cable that does USB 3.x, or 2A, or Display end to end.
It's a mess.