struct memeber can not be Simulink.Parameter?

hi,

I am using HDL Coder to generate RTL code from simulink.

While I want some signal internal a simulink to be tunable, which names 'bp' for example. So I wrote following code:

bp = Simulink.Parameter;
bp.Value = [0;0;0];
bp.CoderInfo.StorageClass = 'ExportedGlobal';

Then the bp signal will appeared as a input port in RTL.

However, if I wrote like this:

reg.bp = Simulink.Parameter;
reg.bp.Value = [0;0;0];
reg.bp.CoderInfo.StorageClass = 'ExportedGlobal';

While generate RTL, it comes out error:

Invalid setting in '<some_block>' for parameter 'Value'.

error using slhdlcoder.SimulinkConnection/initModel

Expression 'reg.bp' for block '<some_block>' returns a Simulink.Parameter object that has property values that need to be evaluated. This object should be instantiated in a workspace and referenced by name in Simulink

So it seems struct member can not be simulink parameter?

[Parker]

I hope the Mathworks team will revisit this question and give an explanation for why this is not allowed. I have run into the same thing, where our team would like to store our parameters in a structure and use them in constant and gain blocks in our model, but Mathworks appears to have disallowed this starting with MATLAB r14sp3, per this older question

Answer 1

[Shivam Malviya]

Hi,

It appears that during the RTL code generation for the attached model, you are encountering the mentioned error due to the use of a struct variable with a field that is a Simulink.Parameter. In your use case, struct variables are necessary to bundle all the global tunable parameters together.

The current initialization of the `reg` variable is causing Simulink model compilation failure, which leads to an error during RTL code generation. To resolve this issue, please follow these steps:

• Instead of setting the field as a Simulink.Parameter, set the top-level struct as a Simulink.Parameter.
• Ensure that the appropriate bus object is set for the struct object of type Simulink.Parameter.

Below is the updated demo_param.m script, which correctly initializes the reg variable:

% Initialize the required value
thr_val = [5;6;7];
reg_val = struct('thr', thr_val);
 
% Create appropriate bus object
Simulink.Bus.createObject(reg_val);
regType = slBus1;
clear slBus1
 
% Create the Simulink.Parameter object
reg = Simulink.Parameter(reg_val);
reg.DataType = 'Bus: regType';
reg.CoderInfo.StorageClass = 'ExportedGlobal';
 
% Set required variables
DT_cnt = fixdt(0,8,0);
ts = 0.1;

However, input ports won't get generated in the RTL code for this scenario involving struct as a Simulink.Parameter.

For more details, please refer to the following documentation pages:

• https://www.mathworks.com/help/simulink/ug/using-structure-parameters.html#bu1k073
• https://www.mathworks.com/help/simulink/slref/simulink.bus.createobject.html

Best Regards,

Shivam Malviya

Answer 2

[Kiran Kintali]

Can you share a sample model?

[dayu lai]

Hi, I use the same demo in other question

https://ww2.mathworks.cn/matlabcentral/answers/888157-how-to-assign-the-name-of-a-multiple-port-while-using-hdl-coder-generate-rtl-from-simulink?s_tid=prof_contriblnk

The demo above can generate RTL successfully. However, if I change the parameter of constant before comparator into structure memeber. The compile of MDL is fail.

See the attached png for detail.

In reality, there will be a lot of tunable value in my design. I just want them to be members of structure, like reg.tunable_value0, reg.tunable_value1 and etc. Otherwise my workspace would be full filled with the global tunable value.

How I can do it?

[Parker]

I would love for an explanation from Mathworks about why this method of storing parameters is not allowed by Simulink

Answer 3

[Kiran Kintali]

These pages contain good info on allowed ExportedGlobal usage in HDL Coder

https://www.mathworks.com/help/hdlcoder/ug/generate-code-for-tunable-parameters.html?searchHighlight=ExportedGlobal&s_tid=srchtitle_support_results_1_ExportedGlobal

https://www.mathworks.com/help/hdlcoder/ug/check-for-unsupported-storage-class-for-signal-objects.html?searchHighlight=ExportedGlobal&s_tid=srchtitle_support_results_2_ExportedGlobal

https://www.mathworks.com/help/hdlcoder/ug/design-guidelines-for-the-matlab-function-block.html?searchHighlight=ExportedGlobal&s_tid=srchtitle_support_results_3_ExportedGlobal