实现了打开串口，对串口进行读写，并且向打印机发送字符！-Open the serial realized on the serial read and write, and send to the printer character!

这是个处理和读写PDF文件的源代码,PDF 是一种跨平台的电子书格式.对于大家做系统时候生成PDF是一种帮助-This is a process and read and write PDF files of source code, PDF is a cross-platform e-book format. For when you do the system is to help generate PDF

U口通信源码,提供了四个接口，打开通信端口，读USB，写USB，关闭通信端口 -U-mouth communication source, provides four interfaces, open communication ports, read USB, write the USB Close communication port

实现证卡打印，实现读磁写芯片校园一体化发卡。-Achieve card printing, magnetic read write chip to achieve integrated campus card.