Hello,
The FMC-CE expansion card has voltage translators on it. It expects 2.5V signals from the FPGA and translates these to 3.3V at the PMOD connectors (which you have the PS2 module connected to). See page 7 of the FMC-CE Card User Guide. So these PMOD interface connectors are 3.3V.
The PS2 module that you’re using looks like Digilent’s PMOD PS2. If it is, then this module has pull-up and series resistors installed on it that handle the 3.3V ↔ 5V conversion for you.
So you shouldn’t need to do any additional conversion.
Also, just FYI, if you are using HDL code to handle this interface, we have a free IP core and background information on accomplishing this available here: PS/2 Mouse Interface (VHDL)
Regards,
Scott