User guide

358 www.xilinx.com System Generator for DSP User Guide
UG640 (v 12.2) July 23, 2010
Chapter 4: Importing HDL Modules
16. Run the simulation. A ModelSim command window and waveform viewer opens.
ModelSim simulates the VHDL while Simulink controls the overall simulation. The
resulting waveform looks something like the following:
The following warnings received in ModelSim can safely be ignored.
# ** Warning: There is an 'U'|'X'|'W'|'Z'|'-' in an arithmetic operand,
the result will be 'X'(es).
# Time: 0 ps Iteration: 0 Instance: /
xlcosim_black_box_ex1_down_converter_transpose_fir_filter_bl
ack_box_modelsim/
black_box_ex1_down_converter_transpose_fir_filter_black_box_
black_box/g0__22/g_last/m2
They are caused by the black box VHDL not specifying initial values at the start of
simulation.