Re: Re (2): USB functionality.

On 12 Mar 2024 at 19:27:04 GMT, "Dan Purgert" <dan@djph.net> wrote:

On 2024-03-12, Roger Hayter wrote:

On 12 Mar 2024 at 16:29:31 GMT, "peter@easthope.ca" <peter@easthope.ca> wrote:
 

In article <2219572717.2fe80b82@uninhabited.net>, Roger Hayter
<roger@hayter.org> wrote:

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.

--
Roger Hayter