[Hardware] Why are USB hubs still using 2.0 ports today?

[FNX Magokiler]

Today there are a lot of peripheral port hubs that still use USB 2.0 ports. These are ten times slower than the worst of the 3rd generation ports. Why is a type of interconnection with worse characteristics still being used after all this time? This interface should have been withdrawn from the market years ago, but even so, it is still used. Why?

USB 2.0 ports are already over two decades old and USB 3.x are old enough that there has been a total replacement of these over time. Since that is what happened with the 1.x ports of the standard. However, we find that USB-C and USB 3.0 port hubs are still using them. Honestly, we all could use them if they were the SuperSpeed type. If you ask anyone about the existence of USB 2.0 ports today, then the typical answer is cost.

Reality? If we are objective we will see that the costs of a USB 3.X port are at most cents higher than the 2.0. Although this is the fallacy of the olive on the plane menu. Such a level of savings does not make sense and ends up causing computers to end up with worse interfaces for peripherals. It is true that if we connect a keyboard, a mouse or some speakers they do not take advantage of a USB 3.X port, but neither does the 2.0. It is best if there are multiple ports with multi-gigabit per second transfer. However, we find that this is not the case. Why do USB 3.X hubs have 2.0 ports today? Well, believe it or not, it is not an economic decision, but a technical one.

The 2.0 interface inside your USB 3.X or Type-C
The key is in the way in which the pins or connectors are distributed in the third generation USB standard. Well, in order to transmit data at high speeds, the pins labeled TX and RX are used, but pins D+ and D– are not usually used to transmit information. The latter are the same data connectors as USB 2.0

Because most devices designed for USB 3.X, both Type A and Type C, do not use the D+ and D- pins, they are completely free to use.

 

 

The peculiarity is that they are not switched between them. That is, the port can send and receive data from both the high-speed pins and the other pins at the same time.

What do manufacturers do? Well, since they are not usually used in peripherals, what they do is derive a USB 2.0 port from each 3.x port, which is totally free. Since for each USB 3.X port that supports the high-speed USB controller, this is the reason why USB 2.0 ports are still used today. That is to say, it is nothing more than a collateral effect of the specification and will continue with USB 4, due to the fact that it is based on the same pin configuration as that of type C.

The particular case of virtual reality glasses
Actually the Data + and Data- pins are used in certain scenarios. This is in the case of USB-C that have the ability to transmit video through the DisplayPort protocol. Because the necessary transfer is very high, they make use of the SSTX and SSRX pins for this, so the data transfer ends up on the USB 2.0 pins.

Devices that make use of this? Well, the headsets for virtual reality or HMD to be able to connect to the PC or the console with a single cable. While the image is sent, the D+ and D- pins are responsible for sending the information captured by the sensors integrated in the unit to measure and follow the movement of the controls and the player. As well as to power the internal hardware of the unit.