Universal Serial Bus

Universal Serial Bus (USB) is a serial bus standard for connecting devices, usually to computers but also used in other devices such as game consoles, cell phones and PDAs.

USB can connect additional equipment such as computer mouse, keyboard, image scanners, digital cameras, printers, hard disk, and networking components. USB has now become the standard for multimedia equipment such as image scanners and digital cameras.

USB is a host-centric bus where the host / terminal stem initiate all transactions. The first package / markers (tokens) produced by the host beginning to clarify whether the packets that follow it will be read or written and what is the purpose of the device and endpoint. Subsequent packets are data packets, followed by a handshaking packet data or a report on whether the marker has been well received or the endpoint fails to receive the data well.

Each process transactions on the USB consists of:
Package token / marker signal (Header that describes the data that follows)
Choice of data packets (including charge rates) and
Status of the package (for the acknowledge / notification of transactions and for error correction)

Designing the equipment using the USB

To make an equipment that can communicate with the USB protocol do not necessarily have to know in detail the USB protocol. Sometimes do not even need the knowledge of USB protocol at all. Knowledge of the USB protocol is only required to know the specifications required for our tool. In fact for mengimplemetasikan USB protocol on FPGA or other assistive devices are very inefficient and a lot of wasted time to design it. Using the USB controller is more advisable in making tools that can communicate over this protocol. USB controller has many forms, from the 8051-based microcontroller that has a USB input output directly to a modifier of the serial protocol such as I2C bus to USB.

USB controllers are usually sold together with the various facilities that simplify the development of tools, including a complete manual, drivers for windows, sample application code to access the USB, the example code for USB controllers, and circuit schematics elektronikanya.

In the development of software applications in personal computers, the communication between the hardware inside the USB hardware is not too much attention because Windows or another operating system that will take care of it. Software developers only provide data that will be sent to the buffer storage USB device and read data from USB devices from the buffer reader. For drivers were sometimes Windows already provide, except for equipment that has special specifications we have to make your own.

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