Maximum Packet Sizes for FX2/FX2LP in Full-speed Mode.

Question: The FX2/FX2LP Technical Reference manual says the buffers appear smaller when the FX2/FX2LP runs at full speed and that packets are fixed at 64 bytes for non-Iso types. Does this mean that we cannot take advantage of the larger (slave) FIFO sizes - such as 512 bytes for bulk transfers - when using a PC that does not support high speed ?

 

Answer:

When FX2/FX2LP is full-speed mode, the maximum packet sizes of the endpoints will always be 64 for non-ISO types. Even though the endpoints are physically large, in full speed mode they appear to the programmer as only 64 bytes deep. You will not be able to take advantage of the larger FIFO size.