文档介绍：英文原文
The serial controller design based on FPGA
Introduction
The use of hardware description language (HDL) is ing a more dominant factor, when designing and verifying FPGA designs. The use of behavior level description not only increases the design productivity, but also provides unique advantages in the design verification. The most dominant HDL stoday are called Verilog and VHDL. This application note will illustrate the use of Verilog in design and verification of a digital UART (Universal Asynchronous Receiver & Transmitter).
Defining the UART.
The UART consists of two independent HDL modules. One module implements the
transmitter, while the other module implements the receiver. The transmitter and receivermodules can bined at the top level of the design, for binations of transmitter and receiver channels required. Data can be written to the transmitter and read out from the receiver, all through a single 8 bit bi-directional CPU interface. Address mapping for the transmitter and receiver channels can easily be build into
the interface at the top level of the design. Both modules share mon master clock called mclkx16. Within each module mclkx16 are divided down to independent baud rate clocks.
UART functional overview.
A basic overview of the UART is shown below. At the left hand side is shown “transmit hold register”, “transmit shift register” and the transmitter “control logic” block, all contained within the transmitter module called “txmit”. At the right hand side is shown the “receive shift register”, “receive hold register” and the receiver “control logic” block, all contained within the receiver module called “rxcver”. The two modules have separate inputs and outputs for most of their control lines, only the bi-directional data bus, master clock and reset lines are shared by both modules.
The UART standard data format.
In figure 3 is shown the UART serial data format. Serial data are contained within frames of 8 data bits, as well as coded inf