说明：  -- 本模块的功能是验证实现和PC机进行基本的串口通信的功能。需要在 --PC机上安装一个串口调试工具来验证程序的功能。 -- 程序实现了一个收发一帧10个bit（即无奇偶校验位）的串口控 --制器，10个bit是1位起始位，8个数据位，1个结束 --位。串口的波特律由程序中定义的div_par参数决定，更改该参数可以实 --现相应的波特率。程序当前设定的div_par 的值是0x104，对应的波特率是 --9600。用一个8倍波特率的时钟将发送或接受每一位bit的周期时间 --划分为8个时隙以使通信同步. --程序的工作过程是：串口处于全双工工作状态，按动SW0，CPLD向PC发送“welcome" --字符串（串口调试工具设成按ASCII码接受方式）；PC可随时向CPLD发送0-F的十六进制 --数据，CPLD接受后显示在7段数码管上。
(- The module s function is to verify the implementation and the basic PC-to serial communication functions. Required at - PC machine on the installation of a serial debugging tools to verify the function of the procedure. - Implementation of a program to send and receive a 10 bit (that is, no parity bit) Serial Control - System, and 10 bit is a start bit, 8 data bits, 1 Ending - Bit. Serial Porter law procedures defined by the parameters div_par decision to change the parameters can be real - Is the corresponding baud rate. Procedures set div_par the current value is 0x104, the corresponding baud rate are - 9600. 8 times the baud rate with a clock will be sent or received every bit of the cycle time - Is divided into eight time slots in order to enable synchronous communication. - Procedures for work processes are: full-duplex serial port in job status, rather than pressing SW0, CPLD to the PC to send "welcome" - String (serial debug tools is set to accept by way of A)