Inter－Integrated Circuit总线是由PHILIPS公司开发的两线式串行总线，用于连接微控制器及其外围设备 。它是同步通信的一种特殊形式，具有接口线少，控制方式简单，通信速率较高的特点。只需要一条串行数据线SDA，一条串行时钟线SCL 。它是一个真正的多主机总线，如果两个或更多主机同时初始化，数据传输可以通过冲突检测和仲裁防止数据被破坏；串行的8 位双向数据传输位速率在标准模式下可达100kbit/s，快速模式下可达400kbit/s，高速模式下可达3.4Mbit/s；连接到相同总线的IC 数量只受到总线的最大电容400pF 限制。SDA 线上的数据必须在时钟的高电平周期保持稳定。数据线的高或低电平状态只有在SCL 线的时钟信号是低电平时才能改变。串行数据SDA的下降沿和串行时钟SCL在稳定高状态时通信启动；SDA的上升沿和SCL在高电平时通信停止。数据传输必须带响应，相关的响应时钟脉冲由主机产生。在响应的时钟脉冲期间发送器释放SDA 线（高）；在响应的时钟脉冲期间接收器必须将SDA 线拉低，使它在这个时钟脉冲的高电平期间保持稳定的低电平。通常被寻址的接收器在接收到的每个字节后，除了用CBUS 地址开头的数据，必须产生一个响应。-Inter-Integrated Circuit bus is a two-wire serial bus developed by PHILIPS company, used to connect the microcontroller and its peripherals. It is a special form of synchronous communication, and has a simple interface cable, the control mode, the communication rate is higher. Only need a serial data line SDA and a serial clock line SCL.It is a true multi-master bus, if two or more host initialization, data transfer by collision detection and arbitration to prevent data corruption　serial 8-bit bidirectional data transfer rate up to the standard mode100kbit/s, the fast mode, up to 400kbit/s up to 3.4 Mbit/s high-speed mode　IC number is only connected to the same bus by bus capacitance of 400pF limit. SDA line must remain stable in the high cycle of the clock. High or low state of the data lines only when the clock signal on the SCL line low to change. The falling edge of the serial data (SDA) and serial clock SCL in a stable high state communications start　communication to stop the r