串口功能的测试程序，分为收发两部分，希望大家用的上-The serial function test program, divided into the transceiver two parts hope you use on

Linux上串口读写程序，首先打开串口，对其进行设置，然后产生一个子进程对子进行对串口进行读，父进程对串口进行写操作。(The demo is used for reading and writing the uart in Linux, there are two thread, the parent fork write the uart, the child thread read it.)