请教马老师：SPI接口的四种模式问题

millwood0

"但是对于SPI输入的情况，我有点不能理解，不知道该是怎么样的"

the typical mode 0 implementation is that you latch data onto the mosi line, then rise sck. most mode 0 chips will then output miso right after the rising edge of sck.

so here is a typical (mode 0) sequence:

  clear sck;
  latch data onto mosi;
  rise sck;
  read data from miso;

millwood0

主要就是看从器件的情况，

that's right. the slave determines the mode of operations and the master just need to speak the same language to communicate with the slave.

the best approach for spi (or other low level protocols like i2c or 1wire) is to write a set of spi routines that read from and write to a spi device. this can be either software or hardware driven.

then you write your device routines that utilize the spi routines.