writing a custom bitfile

i have an encoder that will give me an incremental differential signal.
Do I just add 2 encoder inputs for a single axis and invert one off them in the halfile or do I need to do this in the bit file?
andreas

For differential inputs you need a RS-422 receiver chip, for example a 26LS32

(The FPGA pins have differential capability but lack sufficient common mode
range for encoder applications)

Thanks a lot