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Project.205: Serial Port Device Driver Development

PC16550D Universal Asynchronous Receiver/Transmitter with FIFOs


The PC16550D is an improved version of the original 16450 Universal Asynchronous Receiver Transmitter (UART) Functionally identical to the 16450 on powerup (CHARACTER mode) the PC16550D can be put into an alternate mode (FIFO mode) to relieve the CPU of excessive software overhead In this mode internal FIFOs are activated allowing 16 bytes (plus 3 bits of error data per byte in the RCVR FIFO) to be stored in both receive and transmit modes All the logic is on chip to minimize system overhead and maximize system efficiency Two pin functions have been changed to allow signalling of DMA transfers.
The UART performs serial-to-parallel conversion on data characters received from a peripheral device or a MODEM and parallel-to-serial conversion on data characters received from the CPU The CPU can read the complete status of the UART at any time during the functional operation Status information reported includes the type and condition of the transfer operations being performed by the UART as well as any error conditions (parity overrun framing or break interrupt)
The UART includes a programmable baud rate generator that is capable of dividing the timing reference clock input by divisors of 1 to (216b1) and producing a 16 c clock for driving the internal transmitter logic Provisions are also included to use this 16 c clock to drive the receiver logic The UART has complete MODEM-control capability and a processor-interrupt system Interrupts can be programmed to the user’s requirements minimizing the computing required to handle the  communications link The UART is fabricated using National Semiconductor’s advanced M2CMOS process.


Design and Write a Serial port device driver for 9 pin serial port and implement bacic operations through the driver.

Topics of Discussion:

  • Introduction to Serial Port
  • RS232 Protocol
  • DataSheet Interpretetion
  • Introduction to Serial Port Device Driver
  • Device Operations using Serial Port Driver
  • Establishing Serial Communication between Devices: Byte Transfer
  • Using Interrupts for Serial Communication
  • Establishing Serial Communication between Devices: File Transfer
  • Establishing Serial Communication between Devices: Two way Communication


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