A USB is define as a “universal serial bus”. It is used to connect a device with any computer or system using USB wire. There are 14 different types of USB connectors are available in the market. The most popular and In use connector type is Type C connector. Generally, USB is develop to connect, simplify and improve interface between personal computers and other various devices. The first USB was released in 1996. There are 4 generations of USB:- USB 1.x, USB 2.x, USB 3.x, USB 4.
In general the designs of USB is to make the connections to peripherals to personal computers. USB is used to transfer data to one computer to other device or supply electric power. There are lot of devices available in the market which uses USB to connect with personal computer. i.e. keyboard, mouse, webcam, cameras, printers, mobile phones, network adapters etc.
Objectives to use USB
The interface of USB is really good and self configuring. It adjust the device settings as per it’s need. It can adjust speed or data format, configure interrupts, Input/output addresses or direct memory access channels.
USB connectors are simple to the host so any other devices can use holder.
Generally, USB can take full advantage of additional processing power so any other device can manage themselves.
The USB interface is generally hot pluggable. which means we can change any other devices without shutting down or rebooting.
A very small purpose devices can easily connects with the computer.
Installing a device in port on a running computer .It either configure automatically or system prompts user to locate a driver.
There are wide range of transfer speed is available from a USB devices ranging.
A USB interface is designed to provide a best available latency.
A USB interface is generally designed for all types of device which needs to be connected.
Limitations of USB
Generally, USB cable have limit in length.
It only connects device within 2 meters. It can’t connects devices one room to other room or building to building.
Only, This generation’s USB is fast. It gives 100gbps. Other generations USB are slower.
USB generally uses master/slave strategy to address peripheral devices. Some devices cannot connects devices with USB ports.
There is a host or slave. Host cannot connects all devices at once. each device connects individually.
System Design
A USB system consists a host with one or more multiple peripherals. Some additional USB includes five stars. A USB controller may have one or more controllers with one or more ports. USB devices usually links in series of hubs. A USB device have several logical sub-devices That refers as a device functions. i.e. a webcam with in-built microphone. In which all logical devices connect to a built-in hub that connects to a Physical USB. A communication in USB is through a logical channels. Generally, It calls an endpoint. Each USB device can have up to 32 endpoints. It is rare to have so many endpoints.
Device classes
USB drive
A USB mass storage device is generally standardizes a storage device. Other name of USB drive is pendrive. It has been extend for flash drives or SD card readers. The most personal computers from early 2005 are boot from USB mass storage devices. USB is a secondary bus for a computer’s internal storage. Generally, USB have an advantage of allowing hot-swapping etc. Another use of USB mass storage is portable executions of software without installing in host computer.
Media transfer protocol
A Media transfer protocol (MTP) was designed by Microsoft. The main motive is to give higher-level access to a device’s filesystem than USB mass storage. Generally it is designs to use with portable media players. It adopts a primary storage access protocol of the android operating system. It does not require exclusive access to the storage devices. The con is MTP is not support outside of windows operating system.
Human interface devices
A USB mouse and keyboard is uses with older computer that have PS/2 connectors which has a small USB-to-PS/2 adapter. A mouse and keyboard supports dual-protocol. The hardware of keyboard and mouse detect whether it connects to USB or PS/2 port.
Device Firmware upgrade
Device firmware upgrade (DFU) is a vendor and device independent mechanism to upgrade USB devices. It upgrades USB devices with improved versions provided by manufacturers. During this process USB change their operating mode effectively with PROM programmer. DFU can also give some freedom to flash drives.
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