i2c模块源代码资料，实现掉电记忆功能。有效的保存断电前的数据，让读者更容易熟悉I2C模块，以便日后的开发。(I2C module source code data, realize the power down memory function. Effectively save power before the data, make it easier for the reader to be familiar with the I2C module, in order to develop