Why do I see resolution mismatches when using the HDL Co-Simulation with ModelSim and a Blackbox?
This is a known problem, when using a very small Simulink Simulation period.
There are two ways to work around this problem:
-- Set the Simulink Simulation period to "1 Second"
-- Change the default ModelSim resolution from "ns" to "ps"
This issue has been resolved in System Generator for DSP 8.1.