摘要:串行通信具有成本低，传输距离远，抗干扰能力强等优点，随着大量串行接口芯片的涌现，在单片机系统扩展中串行扩展正逐步取代并行扩展成为外围器件扩展的流行方式。串行扩展技术目前主要分为IIC、SPI、单总线、Microwire总线、移位寄存器方式（51串行口工作方式0）几种，本课题研究的重点是IIC总线串行扩展技术。主要通过具有IIC总线接口芯片的扩展实验，研究IIC总线扩展的软硬件技术。课题分别对具有IIC总线接口的EEPROM芯片AT24C02，时钟芯片PCF8563，数模转化芯片PCF8591进行了扩展实验，设计了三个实验的硬件电路和软件程序，并逐一在Proteus软件平台上进行仿真调试运行。实验结果表明：三个实验皆实现了单片机与芯片的数据交换和读写操作，相关信息通过LED显示器得到显示验证。遵循严格的操作时序，IIC总线扩展技术通过两条信号线可扩展多个IIC总线芯片。应用 Proteus的 ISIS 软件进行单片机串行扩展的设计与仿真，效果直观，真实准确，节省硬件资源。

关键词：串行扩展技术  IIC总线   单片机   Proteus

ABSTRACT:Serial communication has the advantages of low cost, long transmission distance, strong anti-interference ability, with a large number of serial interface chip to emerge, in the expansion of serial extended chip system is gradually replacing the parallel expansion become a popular way of peripheral device extension. Serial expansion technology is mainly divided into IIC, SPI, single bus, Microwire bus, a shift register (51 serial working mode 0) several, the focus of this research is that IIC bus extension technology. Mainly through the expansion experiment with IIC bus interface chip, the hardware and software of IIC bus extension. Research on the EEPROM with IIC bus interface chip AT24C02, the clock chip PCF8563, digital-to-analog conversion chip PCF8591 is extended to experiment, design the hardware circuit and software program of the three experiments, and analyzed the simulation debugging and running on the platform of Proteus software. The experimental results show that: three the experiments are implemented with the chip microcomputer data exchange and read and write operations, the relevant information is verified by LED display. Follow the operation timing of strict, IIC bus extension by two signal lines can be extended more than one IIC bus chip. Application of Proteus ISIS software design and simulation, serial expansion effect is direct, accurate, save the hardware resources.

Keywords:  Serial extension technology   IIC bus   AT89C51   Proteus Software