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Will my iConnectivity interface work with USB-C?

What is USB-C?

USB-C is without doubt becoming the standard system for transferring all sorts of data between computers and peripherals. However there is a lot of misunderstanding and misinformation about what exactly USB-C is and how it works. This article will attempt to dispel some of the myths and give you some useful advice in how your USB-C equipped devices can work best with your iConnectivity interfaces.

The first thing to understand is that USB-C is not a data format itself. USB-C is simply a physical connector designed to allow all kinds of data to be passed though it. So instead of needing lots of different cables and connectors for each type of thing you want to connect, a USB-C cable can basically carry any signal you need. That makes it incredibly useful, and there's no doubt that it will become the standard for pretty much all data transfer in the future.

Before we go any further, it's important to correctly understand the difference between the different types of USB physical connector and the different types of data format that can be transferred along the cable:
  • The different kinds of USB physical connector are referred to with letters:
    • USB-A
    • USB-B (plus USB-B Mini, USB-B Micro etc.)
    • USB-C
In the picture above two different kinds of USB physical connector are shown: the top one is a USB-C connector, and the lower one is a USB-A connector.
  • The different kinds of USB data format are referred to with numbers:
    • USB 1.0
    • USB 2.0
    • USB 3.0
    • USB 3.1
    • USB 3.2
Note that there is no direct correlation between the type of USB data and the type of USB physical connector that can transmit it. For example USB 1.0 data can be transferred through any type of USB cable. So be careful not to confuse the software data stream (the numbers) with the hardware connector (the letters), they are two completely different things.

Pretty much any kind of data can run though a USB-C connector, even data that isn't USB! The types of data that can travel over a USB-C cable include:
  • USB 1.0 (Full Speed)
  • USB 2.0 (Hi Speed)
  • USB 3 (SuperSpeed)
  • USB 3.1 (SuperSpeed+)
  • USB 3.2
  • HDMI
  • Ethernet
  • Thunderbolt (only on some USB-C ports!)
Multiple streams of these can even be passed at the same time!

Laptops and desktop computers with USB-C

We have received reports that many audio interfaces are having problems with some modern computers equipped with USB-C ports. The reason for this is that it seems that there is currently a bug in one of the Intel USB controller chips inside these computers that means many digital audio interfaces will not work correctly and will produce distorted sound or random disconnects when plugged into them. Note that this is not just a problem with our interfaces, it affects many interfaces from other companies too.

Our investigations indicate that there may be problems with the USB subsystems on the following machines (and possibly several others we have not yet tested):
  • Razer Blade laptops
  • Razer Core external GPU enclosure
  • Apple mid-2018 Mac Mini
  • Apple mid-2018 MacBook
If you have one of these machines, or another computer equipped with USB-C ports that seems to be exhibiting problems with your iConnectivity interface, there are several workarounds you can try:

Most USB-C computers also have legacy USB-A ports, and in some cases these legacy USB-A ports are internally connected to a different USB controller chip that does not exhibit this buggy behavior. So the first thing to try is simply to connect your interface to one of the USB-A ports instead of a USB-C port. On many computers (for example the Razer Blade 14" 2017 edition) this will solve the issue immediately.

However some computers do not feature legacy USB-A ports, and others (such as the 2018 Apple Mac Mini) may have their legacy ports internally connected to the same problematic USB controller chip. In these cases the best workaround we have found is to attach an external Thunderbolt 3 hub to one the computer's USB-C ports, and then attach your iConnectivity interface to one of the USB-A ports on the Thunderbolt hub. Note that most common "USB-C hubs" will not work - to work correctly the hub must be fully Thunderbolt 3 compatible. You can recognize a Thunderbolt 3 hub by checking that the following features are listed:
  • The description specifically says that is Thunderbolt 3
  • The USB-C connector shows a small lightning bolt symbol
  • It is capable of 40GB/s data transfer
  • The display port supports 60 Hz operation
Note that Thunderbolt 3 hubs are usually also considerably more expensive than standard USB-C hubs - expect to pay around $150 or higher. We recommend Thunderbolt 3 hubs from CalDigit - we have tested these and they work very well, and seem to be well constructed. They also include an Ethernet port which is very useful if you also intend to use RTP-MIDI over Ethernet, which is standard in many of our interfaces.

If you are using a desktop PC without legacy USB-A ports, a cheaper workaround is to add a PCI card with USB-A ports - theoretically these should work well, though we have not yet tested this solution.

Mobile devices and USB-C OTG

All USB devices must be defined as either be a Host or a Peripheral. In previous versions of USB, a Host port always used a USB-A connector (the rectangular port that you normally find on a computer); whereas the Peripheral always used one of the various types of USB-B connector (either a full-size square connector or a USB-B Mini or Micro connector) like you would find on an external hard drive, MIDI keyboard, or other accessory.

USB-C is different - there is only one type of USB-C physical connector, and devices can either choose to be Hosts or to be Peripherals. Whether they are defined as a Host or Peripheral is determined by the internal wiring of the USB-C port itself. So for example, the USB-C ports on your laptop are generally wired to act as Hosts, whereas the USB-C port on your mobile phone or tablet is usually wired to act as a Peripheral.

However sometimes you might want your mobile device to be a Host instead of a Peripheral - for example if you want to use it with your iConnectivity Audio or MIDI interface. USB-C has a very clever way to do this, using the On-The-Go protocol (usually shortened to OTG). An On-The-Go cable is wired up in such a way that it can convert what is normally defined as a Peripheral to act as a Host instead. So plugging a USB-C OTG adapter or USB-C OTG hub into your iPad or Android tablet will enable it to act as if it is a laptop computer instead of an accessory. 

The most basic solution is a simple OTG cable with a USB-C connector on one end and a USB-B connector on the other. Plug the USB-C connector into your phone or tablet, and plug the USB-B end of the cable into your appropriate socket on  your iConnectivity interface and it should just work.

If you decide to get a USB-C hub, which we strongly recommend, you will have a USB-C connector at one end of the hub (which you plug into your mobile device), and several USB-A sockets built into the hub. Connect a standard USB interface cable to one of these USB-A sockets, and connect its other end to the USB-B socket on your iConnectivity interface as usual.

Note that a basic inline OTG adapter will not charge your mobile device. In order to charge your mobile device while you use it you will need a USB-C OTG hub that also supports the USB-C Power Delivery specification (most OTG hubs do). With a USB-C OTG PD hub you can plug in any standard USB-C power supply to the hub and it will not only power your iConnectivity interface but it should also power your phone or tablet as well. 


New iPad Pro and iConnectivity Interfaces

We have begun preliminary testing on the new iPad Pro equipped with a USB-C port, and various USB-C equipped Android devices. Using a standard USB-C adapter with OTG functionality seems to work very well with all of our interfaces tested. An OTG hub with Power Delivery functionality will also power both the iPad and our bus-powered interfaces, so we strongly recommend the use of a USB-C hub of this type,

Using either a simple inline OTG adapter or an OTG hub, in our tests we found that all MIDI and audio works as expected, including audio pass through on iConnectivityMIDI2+ and iConnectivityMIDI4+

Further Information

For more detailed information on the USB-C specification, please see this Wikipedia article.