HDL coder Fixed-Point and Stimulus-Signal

I am new to HDL-coder feature in Simulink. I have some questions regarding to the workflow of design using HDL-Coder:

1. I have a transfer function in Lapace, do i have to transform it into Z-Space?
2. Does the specified sample time have to be given in every single blocks, or only the (1/z)-Block is enough?
3. After the conversion to fixed point, there is a problem with the data format. My subsystem has sfix32 and the step-block has double. I placed a convert between them but it still didnt work. Is there a solution for that ? I want to keep the normal stimulus signals to compare with the S-Space Block.

Answer 1

[Tim McBrayer]

1. HDL Coder is algorithm-agnostic. If you can represent it with supported blocks and data types in Simulink, HDL Coder will be able to generate HDL for it.
2. You do not need to specify a sample time on every block; you don't even need to specify the sample time on every delay. As long as the design compiles cleanly in Simulink, each block will have a sample time assigned to it. You can see the sample times in color if you enable this through Simulink's menus or by running 'hdlsetup model_name'.
3. This sounds like a Simulink modelling issue. You need to first figure out what numeric values your step-block emits, and what integer or fixed point value best represents these values inside your design. There is a tradeoff here between bit width and accuracy. The Fixed Point Advisor, if you have access to it, can help with converting your design to fixed point.