Hi all

I am needing to have one pic communicate info to another pic. What I want to know is this: lets say I need to send info from pic1 to pic2, and use shiftout on pic one to send the data, and shiftin on pic2 to receive. On pic2, will the pic actually wait for the 8 bits of data to shift in? Basicly Im trying to figure out how to syncronize them as pic2 may not always be ready to recieve data, and pic1 may not always be ready to send it. Can someone please point me in the right direction here?