Take Control of Untangling Connections by Glenn Fleishman

Author:Glenn Fleishman [Glenn Fleishman]
Language: eng
Format: epub
Publisher: Take Control Books
Published: 2022-06-29T00:00:00+00:00

Figure 25: USB4 has separate 20 Gbps and 40 Gbps labeling (left, packaging; right, on devices). The evolution of USB was therefore away from profusion and toward the USB-C single jack/plug type that could work everywhere—truly universal at last (Figure 26)!

Figure 26: Behold the glory of USB-C! (Photo: Marcus Urbenz)

The Emergence of USB-C

Finally, a single connection type that was used on both ends of a cable, reversible by 180° as a plug inserted into a jack across its long end, had a compact factor, and could carry up to 100 W of power (later, up to 240 W). Power flow could go either way: a laptop or desktop could charge a mobile device or power pack, or vice versa.

Note: USB-C accomplishes all this by having a lot of wires—24 in all, arrayed as pins inside the connector in two sets of 12, one on each long edge. These wires have assigned characteristics and when plugged in, controllers send signals over the cable to sort out what’s possible by talking to the cable and the controller on the other end.

With Intel’s adoption of USB-C starting with Thunderbolt 3 and the near-complete convergence of USB on Thunderbolt standards, it’s all perfect, isn’t it?

Well, no. First, people had invested a lot into equipment that had USB Type-A connectors. Early computers with USB-C jacks tended to scrimp, and docks with many USB Type-A ports were in short supply. From 2015 to at least 2019, people complained endlessly—and largely rightly so—that they had to buy and keep handy a large array of cables, adapters, and mini-docks. By 2020, it seemed to settle down: peripherals switched to either be USB-C based or included a cable or adapter, less-expensive docks were widely available, and computer makers—particularly Apple—decided to include more and different kinds of jacks to reduce the hassle.

Second, during the awkward Thunderbolt 3, USB 3.1, USB 3.2, Thunderbolt 4, and USB4 transition, you could wind up buying a USB-C cable that wouldn’t properly connect two devices with USB-C ports, wouldn’t connect them at the highest possible data rate (dropping to 10 Gbps, say, instead of 40 Gbps), or would only pass 15 W or 60 W of power instead of 100 W. That problem still hasn’t gone away, as I explain in USB and Thunderbolt Compatibility, but it has decreased and will improve even more in the near future.

Third, as USB has moved from 3.1 to 3.2 to 4, and added options for power offered by ports and carried by cables, the profusion of markings has become more than baroque (Figure 27). (See USB and Thunderbolt Power for more on the power component.)

Figure 27: It might seem ridiculous, but each of these USB jack labels indicates a different mix of capabilities. (Source: Intel) Thunderbolt doesn’t replace USB, but the convergence of it with USB does help clear away some of the underbrush, as I explain next.

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