一种叫做单片机实现io口桥接的软件设计理念，很简单，将2个io口与另外两个io口实现软件桥接，在主机方实现对iic实现的io扩展-Io port MCU called bridging software design philosophy is very simple, the two ports and two io io port for software bridging the host side to achieve the realization of io expansion ii