Monday, February 2, 2015

what is uart

A UART is usually an individual (or part of an) integrated circuit used for serial communications over a computer or peripheral device serial port. UARTs are now commonly included in microcontrollers.

Short for Universal Asynchronous Receiver-Transmitter, UART is a chip used to manage computer serial ports, disk drive interrupts, screen refresh cycles, and any other device that requires timing. With a serial port transmission, the UART converts the bytes into serial bits and transmits those bits through an asynchronous transmission, stripping out the start and stop bits for each character. Below is a listing of various UART chips. The 16550 chip series is the most commonly used UART.

    8250 UART was the original UART and was capable of speeds up to 9600 bps with a 1-byte FIFO.
    8250A UART was a revised version of the 8250 with an additional register that allowed software to verify it was a 8250 UART.
    16450 UART Slightly faster than earlier UARTs.
    16540 UART capable of speeds up to 9600 bps.
    16550 UART has a 16-byte FIFO.
    16550A UART had same features as previous 16550 UART with new fixes.
    16550AF UART had same features as previous 16550 UART with faster capabilities.
    16550AFN UART had same features as previous 16550 UART except was a ceramic chip.
    16650 UART has a 32-byte FIFO.
    16750 UART has a 64-byte FIFO.
    16950 UART has a 128-byte FIFO.
 

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