USB to USB communication

Question

I have an ARM embedded machine with USB OTG controller and two other (Intel) embedded machines without USB OTG (standard type A connectors only).

I want to configure the ARM machine as host and the other two machines as devices.

How is that possible without creating any network (Ethernet) connection? I am using Linux.

Wait, standard A connectors as in they are hosts. I think that could cause problems. — r_ahlskog, Feb 22 '13 at 15:13
Depending on your bandwidth needs, another possible simple solution would be to set up some software-mediated network using logic level UART ports, if you can tri-state the transmit pins when not talking. — Chris Stratton, Mar 13 '13 at 16:00

unwind · Accepted Answer · 2013-02-28T14:09:11.907

Without additional hardware, I don't think you can do this, at least not "cleanly".

USB A ports are meant to point "upstream" only, i.e. towards the host. Since you have two machines that you want to be devices, that only have A ports, you're a bit out of luck.

It might be doable with two of those USB-link cables and a hub, like so:

                    +--------+
  [ ARM box OTG]----|B (hub) |
                    |        |                      
                    | A    A |
                    +--------+
                      |    |
                      |    |
[Intel box A]---[cable]    [cable]---[A Intel box]

Above, [cable] denotes the Direct cable connection cable, and the A/B/OTG symbols inside each box denote the type of connector being used on each. The OTG port is being used in A (host) mode.

Notes:

I haven't tried this.
It will require the ARM box to have dedicated software to drive the DCC cables, since they're actually active devices.
No idea what is required on the Intel machines, probably more dedicated software.

First you did a top-notch edit job on the original post and then proposed an answer that no matter how perverted it is has a chance of working. Nice! — r_ahlskog, Feb 22 '13 at 15:15

USB to USB communication

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