USB protocol evolution history: technical details from USB 1.0 to USB 4.0

In recent years, USB (Universal Serial Bus) has been widely used in personal computers, mobile devices, photographic equipment, digital TVs (set-top boxes), and game consoles as a universal data and power transmission interface. Since its first launch in 1994, USB has undergone several technological innovations, from the initial USB 1.0 to the current USB4.0, and each generation of changes has brought higher transmission rates and more functions. This article will discuss in detail the evolution of the USB protocol from 1.0 to the latest USB4.0, as well as the important technical details, including physical interfaces, transmission standards, and Thunderbolt technology.
1. Basic Concepts
USB (Universal Serial Bus) is a serial bus standard used to connect computers and peripherals. It not only supports data transmission, but also provides power. The original USB 1.0 was jointly released by Intel and Microsoft in 1994, with a data transmission rate of 1.5 Mbps. In the following 30 years, USB has evolved through multiple versions. The current USB4.0 has increased the speed to 40Gbps and greatly enhanced its functions.
 

1. USB interface type: The physical styles of USB interfaces include Type A, Type B and Type C. Type C has become the current mainstream choice because it supports reversible insertion, high data transmission capacity and multiple functions.

2. USB version: The main difference between different versions of USB protocols lies in the transmission rate and function support. The speeds of USB1.0, USB2.0, USB3.0 and other versions have gradually increased, and more complex functions have been added.
2. USB interface
2.1 Interface type
USB interfaces are mainly divided into three types: Type A, Type B and Type C. Each type has various forms such as standard, mini and micro. Among them, the latest Type C interface has become the mainstream because it supports positive and negative insertion, high transmission rate and rich functions. LeTV mobile phone is one of the earliest devices to adopt Type C interface.
 

2.2 Interface Application
Different types of USB interfaces are used differently in devices. Type A interfaces are commonly found in PCs and some peripherals, Type B interfaces are mostly used in printers and other peripherals, and Type C interfaces are gradually becoming popular in various mobile devices and high-performance peripherals with their rich functions.

III. USB transmission standards
3.1 Transmission rate
The transmission speed of USB has developed from 1.5 Mbps in USB1.0 to 40Gbps in USB4.0.
 

* USB 1.0: 1.5 Mbps

* USB 2.0: 480 Mbps

* USB 3.0: 5 Gbps

* USB 3.1: 10 Gbps

* USB 3.2: 20 Gbps

* USB4.0: 40 Gbps

It is worth noting that starting from USB3.0, the naming rules established by USB-IF have become more complicated. For example, USB 3.2 Gen2x2 means 20Gbps, USB 3.2 Gen1 means 5Gbps, etc. In the latest USB4.0 version, support for Thunderbolt technology has been introduced to make it more functional.
3.2 Thunderbolt Technology
Thunderbolt technology was developed by Intel and incorporates its features into the latest USB4.0. This technology supports a single connection to transmit data, video signals, and charge laptops. The maximum transmission speed of Thunderbolt 3 can reach 40Gbps, including 22Gbps data transmission speed and 18Gbps display bandwidth. Based on Thunderbolt 3 technology, USB4.0 achieves more flexible and efficient transmission.