Oki thanks a lot ! it's a bit more clearer.So just to be sure I understood well.let's say I want to read the register 0x03 of an SPI componentAs soon as I set up the pin DATA to output, that put the SPI component in a kind of "listenning" mode. And each time we set the pin Data to high it write a value to set the register we want to read.Then to read the register 0x03 we set to high the bit i=0 and i=1.And then only after we switch the data pin to input to end the process of writing.Am I right?
so is it because we set up the pin sdioPin (Data) to output before calling digitalWrite that the component knows he has to listen the bit for the register we want to read??