Lpc2000

It is "always both".  It's up to your protocol to decide which data 
stream is "don't care" and when.  Only the master can initiate an 
exchange on an SPI bus.

Krys

--- In lpc2000@yahoogroups.com, "Gus" <gus_is_working@y...> wrote:
> Hello,
> 
> In your opinion, what is the best way to transfer data between 2 
LPC 
> micros using SPI?
> 
> The way I have it now, one is master and other is slave. The slave 
one 
> have 1 pin called DATA_READY. When the slave needs to send data to 
> master, it sets DATA_READY high.
> 
> Now the problem is that when the master reads data, it also writes 
> data at the same time (the way SPI works) How would the slave know 
> that the SPI transaction is read, write or both.
> 
> Thanks,
> 
> Gus