实现 ARM和计算机之间 串行通讯： ARM监视串行口，将接收到的字符在液晶屏上显示出来。 （计算机向串口发送数据是通 过键盘来实现的）-ARM and the realization of serial communication between computers: ARM monitor serial port, will receive the characters in the LCD screen is displayed. (The computer sending