Please refer to AN70707 for hardware design guidelines related to FX3 family. Please note that the requirements in the AN70707 should be met strictly. If you meet those requirements, then you need not worry about the number of layers on the board.
I have another very specific question:
I have a board with two FX3 on it. The FX3 communicate with each other over a 32-bit parallel bus at 100MHz. Do i need a resistor on each data/clock line? I inherited the design from another guy who is not part of the team anymore and in his design he has a 33Ohm resistor on each data line as follows:
FX3(1) GPIO4 ---- 33Ohm ----- FX3(2)GPIO4
what is the purpose of this resistor and do I really need it? I am trying to reduce the board size and if I can do without this resistor, that will save me a lot of space.
Yes, we recommend using 22-Ω series termination resistors to avoid reflection on the GPIF data lines (no need to put it on the clock)
Thanks Nishant. So as long as I have the series terminating resistors on 32 Bus lines I am good.
What about the CTL0 to CTL12 lines? do they need terminating resistors as well?