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bus interface
The USB bus interface handles the interconnection between the electrical layer and the protocol layer. From the interconnection point of view, similar bus interfaces are given by devices and hosts, such as serial interface machine (SIE). The USB bus interface is realized by the main controller. The USB system uses the main controller to manage the data transmission between the host and USB devices.
Its interface with the main controller depends on the hardware definition of the main controller. At the same time, the USB system is also responsible for managing USB resources, such as bandwidth and bus energy, which makes it possible for customers to access USB.
Development history of USB
USB 1. 1
USB 1. 1 was originally initiated by Intel and Microsoft, and its biggest feature is that it supports hot plug. When the device is plugged in, the host detects the device and loads the required driver, so it is far more convenient to use than PCI and ISA bus.
The USB specification was first put forward in 1995 by USBIF * *, which was composed of seven companies, including Intel, IBM, Compaq, Microsoft, Digital and North Telecom. USB IF formally puts forward that the specification of USB 1.0 is 1996+0.0, and the bandwidth is 12Mbps. However, because there were few peripherals supporting USB at that time, motherboard manufacturers did not directly design USB ports on the motherboard.
USB 2.0
USB2.0 is a new interface technology applied in computer field. As early as 1995, there were personal computers with USB interface, but due to the lack of software and hardware support, the USB interface of these personal computers has been idle.
After 1998, with Microsoft's built-in support module for USB interface in Windows 98 and the increasing number of USB devices, USB interface has gradually entered the practical stage.
USB 3.0
Intel Corporation (Intel) and leading companies in the industry jointly established the USB 3.0 Promotion Group, aiming at developing ultra-efficient USB interconnection technology, which is 10 times faster than today.
This technology was jointly developed by Intel, Hewlett-Packard (HP), NEC, NXP Semiconductors and Texas Instruments. Its applications include fast, synchronous and instant transmission of personal computers, consumer products and mobile products.
With the increasing popularity of digital media and the increasing number of transmitted files-even more than 25GB, fast synchronous instant transmission has become a necessary performance requirement.
USB 3.0 has backward compatibility standards, and has both the ease of use and plug-and-play function of traditional USB technology. The goal of this technology is to introduce products that are 10 times faster than the current connection level, and adopt the same architecture as wired USB.
In addition to optimizing the USB 3.0 specification to achieve lower energy consumption and higher protocol efficiency, USB 3.0 ports and cables can also achieve backward compatibility and support future optical fiber transmission.
USB 3. 1
The USB 3. 1 specification was released on 20 13, which is divided into two versions: Gen 1 and Gen 2. Actually, the Gen 1 version is only a waistcoat of USB 3.0 (theoretically, the maximum is 5Gbps, and there is no change), but there is still a Type-C USB 3. 1 Gen 1 on sale, which is equivalent to USB 3.0 Type-C, USB 3. 1 and still retains the Type-A version.
USB 3. 1 has changed a lot. Not only can the Gen 2 version provide twice the transmission speed of USB 3.0 (the theoretical maximum is 10Gbps), but also the released Type-C interface adopts the foolproof design and supports forward and backward insertion. But USB 3. 1 is not supported downwards, so an adapter is needed.
Baidu encyclopedia -USB
Baidu encyclopedia -USB interface