网上找的一些I2C从设备代码都没用起来，于是自己写了一个。能实现读取和写入任意一个字节的功能。功能上目前已经够用，连续读取和写入多个字节的就没有加了。-Online to find some I2C slave device code did not use them, so he wrote a. Can read and write function of the first one byte. Function has been adequate, there is no sequenti