[sdiy] USB Question

[Vladimir Pantelic]

On 23.09.2015 08:10, Tim Ressel wrote:
> HI-Dee Ho!
> 
> I need to design a usb interface that does both host and device, but not
> at the same time. There will be an A and B connector on the front
> panel.  All of the procs I've looked at only have one USB interface. 
> I'm guessing the thing to do here is to use a USB switch.  Anyone have
> some insights?
> 
> Thanks!

many CPU'S have a so called USB-OTG (on the go) interface that allows to
switch roles between host and device.

normally switching to host mode is done by inserting a cable that has
the ID pin (the 5th pin on a USB mini/micro connector) grounded, but it
can of course also be done under SW control.

look at e.g. the STM32F105, it has a: "USB 2.0 full-speed
device/host/OTG controller with on-chip PHY that supports HNP/SRP/ID"