usb is the Universal Serial Bus standard.(Recommended learning:PHPSTORM)
General Serial Bulls (English: Universal Serial Bus, abbreviation: USB) is a serial port bus standard, and it is also an input The technical specifications of output interfaces are widely used in information and communication products such as personal computers and mobile devices, and have been extended to photographic equipment, digital TV (set-top boxes), game consoles and other related fields.
The latest generation is USB 3.1, with a transmission speed of 10Gbit/s, a three-stage voltage of 5V/12V/20V, and a maximum power supply of 100W. The new Type C plug type is no longer divided into positive and negative.
USB is an external bus standard that regulates the connection and communication between computers and external devices. The USB interface has hot-swappable function. The USB interface can connect a variety of peripherals, such as mice and keyboards.
USB was jointly launched in 1996 by Intel and other companies at the end of 1994. It has successfully replaced the serial port and parallel port and has become a must-have interface for today's computers and a large number of smart devices.
The USB version has experienced years of development and has now developed into version 3.0.
For most engineers, the main obstacle in developing USB2.0 interface products is:
They have to face the complex USB2.0 protocol and write their own USB devices. Driver, familiar with MCU programming.
This not only requires considerable VC programming experience, but also the ability to write USB interface hardware (firmware) programs. So most people gave up developing USB products themselves.
USB devices mainly have the following advantages:
1. Can be hot-swapped. That is, when using an external device, the user does not need to turn off and on again, but can directly plug in the USB when the computer is working.
2. Easy to carry. Most USB devices are known for being "small, light and thin", which is very convenient for users to carry large amounts of data with them. Of course, USB hard drive is the first choice.
3. Unified standards. Common ones are hard drives with IDE interfaces, serial mouse and keyboards, and parallel port printers and scanners. But with USB, these application peripherals can all be connected to personal computers using the same standards. Then there are USB hard drives, USB Mouse, USB printer, etc.
4. Can connect multiple devices. USB often has multiple interfaces on personal computers, which can connect several devices at the same time. If you connect a USB HUB with four ports, you can connect it again; four USB devices, and so on, you can connect as many times as you want. , connect all your home devices to a personal computer at the same time without any problems (note: can connect to up to 127 devices).
The above is the detailed content of What bus standard is USB?. For more information, please follow other related articles on the PHP Chinese website!