The, by far. easiest way to make a PC board with a uC - this goes for any bus - is to use a dual port memory. This way you get a totally asynchronous interface. Divide the DPM intp 3 areas (1/2 -1 )data to uC, (1/2 -1 )data from uC, 1 byte PC must read, 1 byte uC must read. Using a byte ( 0xff or 0)removes all metastability if a concurrent read and write occur.

Have fun,

Erik