The UART usually does not directly generate or receive the external signals used between different items of equipment. Serial transmission of digital information (bits) through a single wire or other medium is less costly than parallel transmission through multiple wires. Each UART contains a shift register, which is the fundamental method of conversion between serial and parallel forms. At the destination, a second UART re-assembles the bits into complete bytes. The universal asynchronous receiver-transmitter (UART) takes bytes of data and transmits the individual bits in a sequential fashion. See also: Asynchronous serial communication Specialised UARTs are used for automobiles, smart cards and SIMs.Ī related device, the universal synchronous and asynchronous receiver-transmitter (USART) also supports synchronous operation. One or more UART peripherals are commonly integrated in microcontroller chips. It was also an early hardware system for the Internet.Ī UART is usually an individual (or part of an) integrated circuit (IC) used for serial communications over a computer or peripheral device serial port. It was one of the earliest computer communication devices, used to attach teletypewriters for an operator console.
Early teletypewriters used current loops. Two common signal levels are RS-232, a 12- volt system, and RS-485, a 5-volt system. The electric signaling levels are handled by a driver circuit external to the UART. It sends data bits one by one, from the least significant to the most significant, framed by start and stop bits so that precise timing is handled by the communication channel. A universal asynchronous receiver-transmitter ( UART / ˈ juː ɑːr t/) is a computer hardware device for asynchronous serial communication in which the data format and transmission speeds are configurable.
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