SPI总线系统是一种同步串行外设接口；是一种高速的，全双工，同步的通信总线，并且在芯片的管脚上只占用四根线，节约了芯片的管脚，同时为PCB的布局上节省空间，提供方便，正是出于这种简单易用的特性，现在越来越多的芯片集成了这种通信协议。-SPI bus system is a synchronous serial peripheral interface　it is a high-speed, full duplex, synchronous communication bus, and occupies only four lines in the pin of the chip, pin saves the chip, and provides convenience for PCB layout, space saving, it is out of character of the easy use, now more and more integrated chip of this communication protocol.