Know the Universal Serial Bus (USB)

USB is a standard port on the computer now, every computer that we buy today are always equipped at least one or more USB connectors. USB connectors can be ditancapi variety of devices ranging from mice to printers to easily and quickly. The operating system is also very supportive of the presence of USB, version of windows xp start up even already have the installer of USB devices in one package which include the windows program.

Compared to connect the device to another port type found in computers, the use of USB ports is very, very easy. A decade ago before available USB port on your computer. connecting a device to a computer can make the head spin. These problems include:

• The printer must be connected to the parallel port, whereas most computers produced at that time even until now only comes with one parallel port only. Zip drives that require high speed connections also use the parallel port to connect to a computer. Speed ​​is needed is a high-speed data transfer, while the parallel port can not accommodate such high speeds, so we must be prepared for long wait only for a small copying data.
• Modem, several types of printers, and digital cameras use a serial port to be connected to a computer, but most computers produced at that time only have a maximum of two serial ports. Just info serial port known to be very slow in the process of data transfer, because of data transferred serially bit by bit.
• Devices that require a faster connection should be fitted with a separate card, which of course this requires a separate space if you want to be installed on the computer card slot. lucky if there was still some slots in our computer

The purpose of the creation of USB is to end the problem. Universal Serial Bus (USB) provides a single, standard and easy to connect the device to a computer up to 127 devices in a single USB port.

Some examples of devices that have been made ​​in the version of USB include:

• Printer
• Scanners
• Mouse
• Joystick
• Digital Cameras
• Webcams
• Modem
• Load speakers
• Phone
• Video phone
• etc.

CABLE AND USB ​​CONNECTORS
Connect USB devices to a computer is easy. You just need to find a USB port on the back of your computer, then plug the USB connector into the USB port, and complete.

If you plug your device is a new device that has not been previously installed on your computer, your computer's operating system automatically recognizes it will try to auto detect. If the device driver is already installed on your computer then you can immediately use these devices. USB devices can be connected-off whenever required. Easy is not it?

Many types of USB device comes with its own USB connector cable. There are 2 types of USB connectors on the market ie the USB connector type A and type B. Using a standard USB connector type A and B to prevent consumer confusion. Use socket connector type A to USB type A and type B connector to the USB socket type B.

USB HUB
Most computers are currently only has at most 4 USB ports. What if you need more than 4 USB ports for your devices? Of course you can use a USB hub. When even this already widely available USB hub on the market ranging from tens of thousands of dollars you can get it. USB standard capable of supporting up to 127 devices on one port, one of which is a USB hub.

Generally has a 4 port USB hub, in some other types can be more than that. Plug in a USB hub to the USB port on your computer, then plug your USB devices to the hub. By connecting the hub-hub to each other you can provide up to tens of USB ports on your computer.

USB standard is able to provide supply voltage to the device that is connected to that port. Of course, devices requiring high power such as printers and scanners should have its own power supply, but devices that only require low power such as mice and digital cameras can be obtained directly from the USB power supply. 500mA USB power supply voltage reaches 5 V.

PROCESS THAT HAPPENED in the USB
When the host (computer) dole USB device, the host record devices connected to the USB bus and set the memory address for each device. The process is called enumeration. USB devices are also directly initialized by the host when connected to the USB bus. Hosts are also trying to find and choose the type of data transfer what is appropriate for the device. For example:

• Interrupt - for devices that only require a small data transfer such as mouse and keyboard
• Bulk - for devices that require large data transfers such as: printers
• isochronous - for devices that require two-way data transfer, and require high resolution such as: speakers and webcam

Hosts can also send commands and record the necessary parameters using the control packet.

Once the device is recorded by the host, the host and then set the total bandwidth required by the devices that use isochronous and interrupt modes. The device with the data transfer mode can use up to 90 percent of the total 480 Mbps USB ports provided. After 90 percent of the bandwidth is used, the host will be denied access to the isochronous and interrupt the other. Control packet and packets for bulk data transfer type and then use the remaining total bandwidth (at least 10 per cent).

Universal Serial Bus (USB) divides the available bandwidth in the form of frames, the host and control frames. Frames contain 1,500 bytes, which is formed every millisecond. In the frame, the device with isochronous data transfer mode and the interrupt get its own bandwidth allocation according to bandwidth requirements of these devices.

USB CHARACTERISTICS
USB has the following characteristics:

• USB can be connected to 127 devices, either connected directly or through a hub.
• With a single USB cable to connect USB devices as far as 5 meters from the computer. With a USB hub device to connect as far as 30 meters, using only a hub 6 cable only.
• With USB 2.0 data transfer speeds can reach 480 Mbps (Megabits per second).
• The USB cable has two wires for the +5 V power and ground and a pair of wires as the data cable.
• The USB cable that is able to have power supply voltages up to 500 mA at 5 V.
• Devices such as a mouse can instantly get the power supply directly from USB. The printer requires a separate power supply so it does not require a power supply from the computer.
• USB devices can be connected-disconnected from the computer whenever needed with ease.

USB 2.0 TYPE
USB 2.0 standard was released in the market since April 2000 which is the upgraded version of USB series 1.1. USB 2.0 (High-speed USB) provides additional bandwidth for multimedia and storage applications that have a data transfer speed 40 times faster than USB version 1.1. USB 2.0 also uses the same connectors and cables as its predecessor version so that the devices used to take advantage of previous versions can also be used in USB 2.0.

USB 2.0 Supports three speed modes (1.5, 12 and 480 Mbps), USB 2.0 is capable of supporting low berbandwith devices such as keyboards and mouse devices as well as high berbandwith like high-resolution web cam, scanner, printer and high berkapasitias memory system. USB 2.0 allows users to runa variety of USB devices at one time simultaneously ,without having the slightest disturbance .

Posted in: Hardware,Networking