Home security system based on Mega2560 and Mini (or Uno)

Hmm, i thought a fifo chip was to help with that, but i must have been mistaken.

A FIFO is used if some device is delivering data to fast for the recipient to handle. The data is fed into the FIFO and the recipient get it out in the same order as it was entered but at the speed it is able to handle. I guess you see that this doesn't help anything in your case.