SPI(serial peripheral interface)总线是由Motorola公司提出的一种4线制同步串行外设总线接口,包括时钟、使能、输入和输出4根引脚,主要用于CPU与各种外围器件以串行方式进行通信。为了进一步减少接口,介绍了在一款用于射频芯片数据/控制接口的3线制SPI接口的电路设计,通过采用半双工工作模式,接口电路在减少一个引脚的情况下实现双向通信。介绍了3线制SPI接口的电路结构及其工作原理。该SPI接口在0.18μm工艺下实现的版图总尺寸约为240μm×460μm,在10 MHz工作频率下的功耗约为2 mW,通过仿真验证,3线制SPI接口功能正确。
Serial peripheral interface(SPI) is a synchronous serial peripheral bus,which is presented by Motorola company.It consists of four pins,clock,enable,input and output.CPU can transact information with the peripheral device by this interface.The design of a 3-wire SPI interface for designs with less pins is presented,which is a part of a RF chip.The method of half-duplex was adopted to meet the demands of bi-direction communication and less pins of interface.The architecture and work flow of the SPI is described.The total layout of SPI circuit is 240 μm×460 μm,and the power dissipation is 2 mW at 10 MHz.The results of simulation prove that the SPI works properly.