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Swapping the Polarity in a UCF File (or even in the VHDL...)

I have a piece of hardware connected to an FMC, I know for a fact that there is a design fault and the hardware has a polarity inversion along the FMC pins. I want to simply try and quickly correct for this.

I tried doing it in the project, on the LVDS buffers, the inputs were connected to a "not" to try and flip them, this gave me this error for the pins:

NgdBuild:925 - input net 'usr/fmc2_map/la[0].fmc_la_buf/io_n_INV_1415_o'
   is connected to the incorrect side of buffer(s):

Next I tried editing the UCF file:

NET "fmc2_la_n[0]"                                LOC = G20 ;   # IO_L10N_MRCC_26
NET "fmc2_la_p[0]"                                LOC = F21 ;   # IO_L10P_MRCC_26
NET "fmc2_la_n[1]"                                LOC = H20 ;   # IO_L11N_SRCC_26
NET "fmc2_la_p[1]"                                LOC = H19 ;   # IO_L11P_SRCC_26

I tried swapping over the n and p, I'm told that I'm inverting the polarity (which is what I want to do) and it tells me to add this:

XIL_PAR_ALLOW_LVDS_LOC_OVERRIDE

But where do I add this, or how do I disable these messages?

Solution

  • For the weary traveller....

    Type this into the command line before launching ise:

    export XIL_PAR_ALLOW_LVDS_LOC_OVERRIDE="1"