SPI（Serial Peripheral Interface）串行外围模块接口是Motorola首先在其MC68HCXX系列处理器上定义的，它是一种同步的高速串行通信协议。它可以使单片机与外围模块之间进行数据交换，比EEPROM,Flash,实时时钟，AD转换，数字信号处理器和数字信号解码器之间交换数据，同时应用比较多的是用来作为按键等外设的扩展。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有主从两种工作方式，可以工作在3线或者4线模式下。-SPI (Serial Peripheral Interface) is a Serial Peripheral Interface module is Motorola first defined on the MC68HCXX series processor, it is a kind of synchronous Serial communication protocol at a high speed. It can make for data exchange between single-chip microcomputer and peripheral modules, block than the EEPROM, Flash, real-time clock, AD conversion, digital signal processor and digital signal for exchanging data between decoders, and application more is used as an extension of the peripherals like buttons. SPI bus system is a kind of synchronous serial peripheral interface　Is a kind of high speed, full duplex, synchronous communication bus, and on the pin of the chip takes only four lines, saved the chip pins, save a space for PCB layout at the same time, provide a convenient, it is out of the characteristics of this kind of simple and easy to use, now more and more chip integrates the communication protocol. SPI has master-slave two ways of working, can work under the mode of