USB functionality.

There are altogether too many unknowns here. Looking at the date of the photo - 2015 - some phones of that era could support USB OTG but were unable to supply power to connected peripherals, meaning you would need a Y cable to supply that separately. Others could do the job inclusive of power delivery, others couldn't work in OTG mode at all. Generally you couldn't use OTG and charge simultaneously, it's a role reversal that early USB wasn't designed for.

Things are different with USB-C but of course that is much later.

But can even USB-C accept a signal input (keyboard and mouse for instance) and unrelated signal output (audio for instance) on the same physical socket? I ask only out of curiosity.

The setup is rarely tried. Appears that nobody can reply.

A keyboard or mouse sends tiny amounts of data; a few bytes per second. In principle the link should be able to fit that in without significant drop-outs in audio output. WIth so many details involved, a general answer is difficult. When all else fails, we can test and see what happens. =8~)

Regards, ... P.

So you could use an overarching protocol which was bilateral (ethernet anyone?) and send and separate messages both ways. What I was aksing was whether within the USB protocol there was provision for using some pins in for one electrical signal (bi or uni-directional) and other pins for another electrical signal. Because that would be the only way to do it without special software on at least one of the devices.

There's only one set of pins (well, two sets if you count USB2 / USB3 -- but you can only use one set at a time).

USB2 -> D+/D- (Bi-directional / Half Duplex) USB3 -> TX1+/TX1- and RX2+/RX2- (optionally Full Duplex, IIRC)

As I recall the "Tx" pair is "Host Transmit to Peripheral", and "Rx" is "Host Receive from Peripheral", but it's been a while since I read up on the USB3 / USB-C implementations.

Usbc seems to have about 20 pins, that's why I asked.

Yeah, that's just to allow the connector to be flipped over, and still connect to the host / peripheral. The host/peripheral ports themselves only have one orientation.

Certainly.

That's normal USB functionality. It is a bus. You need a hub, though, in order to split the cables, one for each device.

The only problem is which device supplies the power and in what direction.

It'll be fine, I use my laptop all day everyday, USB headset for phone, USB network adapter on the same host port for connectivity (including the phone). Works fine. USB was designed for that from the outset. The retro-fit is splitting power delivery from the host vs device relationship. The early versions of USB always contrived that the host provided the power, USB-C allows you to reverse that relationship so you can have e.g. a phone or laptop on charge via USB while still controlling connected peripherals.

USB-C supports SuperSpeed which uses two additional pairs on top of USB2 and also allows for full-duplex. That is what the additional contacts on a USB3 A plug are for.

Except what Roger is talking about is the "spare(tm)" contacts in a USB-C cable :

GND TX1+/- VBUS CC1 D+/- SUB1 VBUS RX2-/+ GND <-- Used

GND RX1+/- VBUS SUB2 D-/+ CC2 VBUS TX2-/+ GND <-- "spare(tm)"

And that's assuming all the wires are actually *in* the cable, and the manufacturer didn't just cheap out and common things "vertically" (e.g. TX2+ is common to RX2+, like in "Amazon Basics" cables).