基于单片机的ram扩展应用，i2c实例，没有问题，完全可用，提供proteus仿真图。

预先设置led灯状态，写值入外扩ram,接着读取外部ram,如果结果正确，则led灯改变状态。-Ram extension based on single chip application, i2c example, there is no problem, fully available, provide proteus simulation map. Pre-set led light state, write the value into the foreign expansion of ram, then read the external ram, if the result is correct, then led lights to change state.