spi用的什么总线,spi与总线是什么关系？spi难道就是一种总线结构吗

SPI传输协议是一种串行传输方式，其实和I2C很类似，都是总线上可以挂很多外设。不过硬件上的连接很简单，几根线就搞定，外设之间地址都是通过外设上本身的HIGH和LOW组合完成的

The SPI protocol is a widely accepted and easily used
serial transfer protocol. It is fast and efficient, allowing for
simultaneous bi-directional data transfer. The protocol
involves a master-slave configuration which includes a
master device and one or more slave devices.