tq2440串口通信源程序，自带的所以代码在一个程序中，不利于初学者，这个代码利于初学者对串口的学习-tq2440 serial communication source, it comes with a program code is not conducive to beginners, this code help beginners learn the serial port

这是一个用于TQ2440开发板裸机开发的串口通讯程序-This is a used to TQ2440 development board bare-metal serial communication program