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A Simple Analysis of the USB connector’s Data

Author:danny / time:2018-06-21 / The number of clicks:949

With the rapid development of the IT industry, there is an urgent need to update various software and hardware. The increasing demand for data transmission rate between an external device and host led to the development of the USB connector. The USB or universal serial bus is a free standardized connector developed by Intel, Microsoft and other companies to simplify interconnection between computers and external devices. It does not only support connection between various computers and external devices, but also integrates digital multimedia.

The main features of the USB connector are Plug and Play and Hot Plugging, combining the I/O of various external devices into one with automatic configuration capability. The USB can be automatically detected and installed.  It is very convenient and easy to use. Hence, there has been an increase in USB-based external devices, such as keyboards, mice, CD players, modems, scanners, game controllers, etc., and a decline in external devices with no independent I/O connections.  In other words, host-controlled external devices are reduced while intelligently-controlled external devices increased. After the USB bus standard is upgraded to version 3.0, the maximum transmission bandwidth can  reach up to 5.0 Gbps, which supports full-duplex. This optimizes power management, enabling the host to identify devices faster and process data more efficiently.
 
The USB connector has four data transmission modes; namely, control transmission, synchronous transmission, interrupt transmission, and batch transmission, with corresponding properties.
1. Control transmission: establishes a control channel between the external device and host to achieve transmission of control, status, configuration and other information. This transmission mode is applied to each USB.
2. Synchronous (Isochronous) transmission: supports data transmission with periodicity, delay and bandwidth, keeping data transmission rate unchanged. This type of transmission has no error checking, so correct transmission of data cannot be guaranteed.
3. Interrupt transmission: often used by input devices such as gamepads, mouse and keyboard. It has the characteristics of small data transmission, no periodicity, and fast response.
4. Batch transmission: generally applied when there is significant amount of data transmitted between the external device and host. The USB transmits data provided that the bandwidth is satisfied; this is common in printers, scanners, digital cameras, etc.

A new interface standard has been created in input and output devices on a computer due to the emergence of the USB connector. It helps the device become hot-swappable, capable of plug-and-play and auto-configurable, making device connectivity more standardized. At the same time, the new cascading star topology of the USB connector contributes to the further development of external devices, making computer peripheral use more convenient and faster. The newly upgraded USB 3.0 standard allows the data transmission rate to reach a new level, furthering development of the industry in the future.

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