Max 10 ADC Simulation - Can't get it to work properly

The above code sets the ADC output values to fixed numbers (12'h111, 12'h222 etc) but this could easily be changed to a sinewave or whatever you want.

It is a little harder to control this value from the testbench but I don't believe it is impossible.

In general, if you can model your outside world in the test bench (like I did with my inductor capacitor buck converter model) then you can simulate the whole thing in its operating environment. The biggest issue is that the analogue world tends to work in the milliseconds to seconds realm and that can take a little while to simulate.