Description

The following error is seen when running functional simulation of the PCIe example design in ModelSim.

Loading unisim.mmcme2_adv(mmcme2_adv_v)
# ** Fatal: (vsim-3729) Value ?(1095521093) of generic "clkfbout_use_fine_ps" is out of range false (0) to true (1).
# Time: 0 ps Iteration: 0 Instance: /pcie_rc_rp_testbench_modified/rp/sim_ver20/reggen_to_pcie_rc_for_sim_2/xilinx_rc_sel/xilinx_pcie_rc_modified_sel/gt_top_i/pipe_wrapper_i/pipe_clock_int/pipe_clock_i/mmcm_i File: /eva/fpga/xilinx/13.4/ISE_DS/ISE/vhdl/src/unisims/primitive/MMCME2_ADV.vhd Line: 125
# FATAL ERROR while loading design

Why does this occur and how can I resolve it?

Solution

The range mismatch can occur due to an incorrect order of library loading in a mixed-language design.

For example, you might set the language as VHDL and simulation needs to compile both VHDL and Verilog source files. 

In the generated ModelSim simulation script (simulate_mti.do), the order is expected to be unisims_ver prior to unisim.

vlog -work work -sv +incdir+../../source \
+define+SIMULATION \
$env(XILINX)/verilog/src/glbl.v \
-f board_vlog.f

vcom -work work -f board.f

vsim -voptargs="+acc" +notimingchecks -L work \
-L unisims_ver -L unimacro_ver \
-L unisim -L unimacro -L secureip -t "1ps" \
glbl \
work.board

If you use your own script and it specifies "-L unisim" first, the error will occur.