Fixed-step or Variable-step when designing with HDL coder

Can you use "Variable-step" with solver still set at discrete (no continuous states), or does the design have to be in fixed-step in your model configuration parameters settings when you are designing for HDL Coder? I initially thought that it should always be only fixed point, hence people also use fixed point designer, but then one also come across Simulink examples which uses Variable-step and also to demonstrate HDL coder. So I'm confused now. Hope someone can shine some light on this for me please. Thanks

Fixed-step or Variable-step when designing with HDL coder

Answer 1

[Tim McBrayer]

You can use variable-step discrete with no continuous states, but I don't think there is much benefit to doing so.

[DN]

Tim, why would you say that (no benefit)? Because you wont be able to implement it on a FPGA?

[Tim McBrayer]

No, a variable step solver shouldn't cause you any issue. I was trying to say that as far as the HDL portion of your design is concerned, there is nothing to be gained by using a variable step solver. All rates for the portion of the model converted to HDL must be fixed and discrete, irrespective of the Simulink solver used.

If your larger design benefits from the variable-discrete solver in some way then there is no issue with using that solver.

[DN]

Thanks makes sense