SPI Problems

Hi siedler.

I'm not sure I have understood your questions.

It seems you want to transmit data from the master to the slave but also from slave to master, and this is feasible.

But this is possible only upon master request. Namely, when master sends data, the slave transmits back the content of its tx register. The two data transfers (M->S and S->M) take place in the same time, on the same clock pulses, so slave tx register must be preloaded with correct data and ready to answer at the very first sclk pulse.

The slave, being a slave, can't initiate a transmission itself: it always must respond to a master request.