Clock Domain Crossing (CDC)
Rule of Thumb -
FIFO: if the sender has a higher data rate than the reciver, then you have to use a FIFO. Size of this fifo depends on the difference in data rates between sender and the reciver. In this case you need to calculate the difference in the data rates to know exactly how big your FIFO needs to be.
2FF: In cases where the sender and receiver clocks are the same but there is a skew between them, then you can use a double flop synchronizer to handshake the data accross the clock domains.
