Can I use two micro-USB receptacles on a single device so the user has the option of using either?

Question

I make a USB MIDI device and am designing a new version. I'd like to have two micro-USB receptacles in different locations so that the user can choose either, for ergonomic reasons. The easiest thing seems to be to just wire both receptacles to the uC and supply a receptacle cover for the one that isn't being used, instructing the user to never plug a cable into both receptacles at once. I suspect that this isn't a "valid" approach. Is there an accepted way to do this?

Answer 1

Using two sockets on the same bus seems like a poor idea, both because of signal integrity (each socket's routing ends up becoming a long stub when the other is in use) and the risk of hardware damage if someone does plug both ports in (especially if they share VBUS).

Instead, consider the use of a USB switch IC similar to the ones in the USB portion of KVM hubs (which do the same thing of fanning in multiple USB hosts to the same peripheral devices). An example IC for this (no endorsement for this device or its manufacturer) would be something like FSUSB30.

You should be able to play some tricks by detecting the VBUS of one line and using that as the select signal for the switch IC. This avoids the need to manually configure the port.

Of course, as mentioned in the comments, a mechanical design for a routing channel could allow cables to neatly exit a single port and then reach either side without making electrical changes or adding a device to your bill of materials.

Answer 2

You'll want an easy way to switch to using either data pair. In the easiest case, your microcontroller's IO matrix is flexible enough to route either one or another pair of pins to the internal USB PHY, or you have two USB PHYs.

Most MCUs don't have that. Instead, a very simple switch IC can be used, controlled by which of both USB ports has external VUSB plugged in, to mux.