I have a board with a ColdFire 5329 and an AD7689. I am using SPI to talk to the AD7689. The SPI wants to be configured for the same number of bits for data in and data out. The AD7689 expects 14 bit data in and 16 bit data out. Can I just pad out the data for the AD7689 with 2 bits to get consistent data lengths? Do I pad with least significant bits?