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The USART's synchronous capabilities were primarily intended to support synchronous protocols like IBM's synchronous transmit-receive (STR), binary synchronous communications (BSC), synchronous data link control (SDLC), and the ISO-standard high-level data link control (HDLC) synchronous link-layer protocols, which were used with synchronous voice-frequency modems.
128-byte buffers. This UART can handle a maximum standard serial port speed of 921.6 kbit/s if the maximum interrupt latency is 1 millisecond. This UART supports 9-bit characters in addition to the 5- to 8-bit characters that other UARTs support. This was introduced by Oxford Semiconductor, which is now owned by PLX Technology.
The 16550 UART (universal asynchronous receiver-transmitter) is an integrated circuit designed for implementing the interface for serial communications. The corrected -A version was released in 1987 by National Semiconductor . [ 1 ]
Pmod interface (peripheral module interface) is an open standard defined by Digilent in the Pmod Interface Specification [1] for connecting peripheral modules to FPGA and microcontroller development boards using 6 pins. Pmod or Pmods may also refer to modules compatible with the Pmod interface.
Once a UART, and a timer if necessary, has been configured, the programmer needs only write a simple interrupt routine to refill the send shift register whenever the last bit is shifted out by the UART and/or empty the full receive shift register (copy the data somewhere else). The main program then performs serial reads and writes simply by ...
Modern devices use an integrated circuit called a UART to implement a serial port. This IC converts characters to and from asynchronous serial form, implementing the timing and framing of data specified by the serial protocol in hardware. The IBM PC implements its serial ports, when present, with one or more UARTs.
UARTs that lack such support, like the 16550, may suffer from buffer overruns when using software flow control, although this can be somewhat mitigated by disabling the UART's FIFO. [1] Finally, since the XOFF/XON codes are sent in-band, they cannot appear in the data being transmitted without being mistaken for flow control commands.
The 8250 UART was used in several 8-bit computers at least since 1978. IBM used the 8250 UART in the IBM PC (1981). The 8250A and 8250B revisions were later released, and the 16450 was introduced with the IBM Personal Computer/AT (1984). The main difference between releases was the maximum communication speed. [4]