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The original USB connector seems to be the only connector where it is always the wrong way up. Everyone has had the experience of trying to insert a USB connector, finding it won't go, turning it over. It still won't insert. Turn it back to the first orientation and finally it works. I have never heard a good answer as to why such a horrible connector was chosen for the original USB. It only has four signals in it and even in the mid-90s it was obviously too large. The motivation for having different plugs at each end of the cable was apparently to stop anyone from accidentally trying to use the cable to plug two computers together and frying something. Some sense prevailed and it didn't take long for a couple of much more practical mini-USB connectors to be created, for phones and cameras, but for computers the horrible old connector lived on. The only worse design is using a vehicle cigarette lighter outlet for recharging your phone, but at least it has the excuse that it was never designed to be a power outlet, it was designed to light your cigar. In 1956.
There is a new USB connector, known as USB Type-C. It is much smaller than the old connector. The picture to the right shows the new connector with one of the old Type-A ones for scale.The first thing to love about it, apart from its size, is that it can be inserted either way up. The cable is also symmetric, it has the same connector at each end. However, it has two major new features that previous versions of USB did not.
Firstly, it can carry power. The old USB connector allowed a small amount of power (2.5W) to be used so that a PC could power a mouse or a keyboard. Ten years ago, disk drives sometimes had two USB connectors since they needed more power than one was able to provide. The new connector is designed for power to flow the other way too, into your computer. The power can be as high as 100W. The second feature is that a display can be connected.
The intention is that these two features are used together. Your display already has power. Connecting a single USB Type-C cable between the display and your laptop (or phone) allows the laptop/phone to be charged and for it to drive the display. The display can also provide a USB hub so that other devices such as backup disks, printers, and so on can be connected. When you arrive at your desk or at your home, you just make the single connection and your computer is powered, it has a big display, and it can access the other peripherals. The picture below shows the sort of setup that is possible with computers, displays, hubs, printers and more all networked together and powered from a single supply to the monitor.
The latest Macs, for example, work like this. My older generation MacBook Air has two USB connectors, a display connector, and a power connector. The next generation just has one USB Type-C connector, as do some Chromebooks. As Apple put it on their website:
The amazing USB-C port offers charging, quick USB 3 data transfer for connecting to external devices and peripherals, and video output that supports HDMI, VGA, and DisplayPort connections. All in a small, reversible design that’s one-third the size of the current USB port.
I should also point out that USB protocols are orthogonal to the actual physical connector. USB 3.0 and 3.1 standards can both be used with the USB Type-C connector (2.0, too, if you insist). This connector is being adopted very fast with millions of devices already shipping. In fact it is the fastest adopting specification of the most popular interface in history, rapidly replacing not just the older USB standards, but other legacy connectors for displays, network cables, power cables and more. It is not an interface that anyone designing electronic systems can ignore. In January at CES I think you can expect pretty much everything to have a USB Type-C connector.
Talking of designing equipment, if you are creating an SoC that will work in the USB Type-C environment, driving a display and taking in power in addition to data transfer capability, then you need IP that supports this functionality. Today, at USB Developer Days in San Diego, Cadence is announcing the industry’s first IP subsystem with pre-verified components including a single-chip port controller IP that integrates USB Type-C, USB Power Delivery and DisplayPort Alternate Mode (Alt Mode). This new design IP enables the development of single-chip solutions for combining video, audio, USB and up to 100W of power on a single external connector. Support of this smaller, multi-function connector can reduce board size and BOM cost. Use of pre-verified IP makes SoC integration faster and lower risk, delivering a USB Type-C solution earlier.
The complete subsystem includes:
The diagram below shows how the various subsystems fit together to deliver the enhanced functionality. The connector itself is at the bottom of the diagram, above it the PHYs and on up to the various controllers.
Like in Lord of the Rings where there is "one ring to rule them all", this is "one connector to rule them all."
More information about the Cadence USB Type-C solutions is available here.