SPI modes

May 20, 2006 0 Replies

Hi,



I'm trying to understand what are all the valid configurations for SPI devices both in simplex and duplex case. From what I found so far they are the following:



mode 0: CLK starts low, write on rising, read on falling edge (aka micro wire plus) mode 1: CLK starts low, write on falling, read on rising edge (aka original micro wire) mode 2: CLK starts high, write on falling, read on rising edge mode 3: CLK starts high, write on rising, read on falling edge



I assume that these define the transitions both on the MOSI and the MISO lines. This means that reads / writes always take place on the opposite edge.



I got the following diagram about the above four modes showing the transitions on both lines (data out=MOSI):



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As I understand it's not according to the above definitions, since write on MOSI and read on MISO take place on the same edge. Is it still a valid configuration?



Thanks, Imre



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