How can I profile a Simscape Electrical Model for C2000 MCU?

I have a simple buck converter model adapted to run on a C2000 (F28379D LaunchPad XL) using the C2000 MCU blockset, which just runs fine there. Now I want to see how much CPU time it consumes using the "Hardware Profiler" block and placing the model in a function-call subsystem. When I now try to compile the model, I get an error:

"Error:Goto/From connections cannot cross nonvirtual subsystem boundaries. The only exception is when a goto is connected to a state output port"

I've attached the model that throws the error.

How can I create a model using "powergui" that is suitable for profiling on the C2000 platform?

Many thanks in advance!

[Raghava S N]

Hi @Jens,

The issue seems to arise from the Goto/From blocks used in the "powergui" and "Buck Converter/Current Measurement" subsystems.

Please refer to these MATLAB Answers posts regarding the same issue-

1. https://www.mathworks.com/matlabcentral/answers/2046170-goto-from-connections-cannot-cross-nonvirtual-subsystem-boundaries-the-only-exception-is-when-a-got
2. https://www.mathworks.com/matlabcentral/answers/39443-goto-from-connections-cannot-cross-nonvirtual-subsystem-boundaries-the-only-exception-is-when-a-got#:~:text=Use%20normal%20signals%20instead%20to%20exist%20the%20triggered%20subsystem.

There are a few possible solutions you may choose to employ-

1. Use normal signals to exit the "powergui" block
2. Use global Data Store Read and Write - https://www.mathworks.com/help/simulink/slref/datastorewrite.html, https://www.mathworks.com/help/simulink/slref/datastoreread.html

Hope this helps.

Regards.

Answer 1

[Jens]

Hi @Raghava S N,

many thanks for your explanation. I changed all Goto/From blocks in my model. Now the on ly ones that remain are the ones generated by powergui during compilation. I tried moving the powergui into the function. This solves the problem with the Goto/From pairs, but now the time step needs to be inherited which is not possible for powergui (and most blocks in Simscape/Electrical).

I'd appreciate any hints on how to use Simscape/Electrical in triggered functions as I'm interested in determining execution time on FPGAs and MCUs.

Again, many thanks for your efforts!

Best,

Jens

[Raghava S N]

Hi @Jens,

This link states that triggered subsystems inherit their sample times from the triggering signal - https://www.mathworks.com/help/simulink/ug/managing-sample-times-in-subsystems.html#:~:text=For%20triggered%20subsystems%2C%20in%20general%2C%20the%20subsystem%20gets%20its%20sample%20time%20from%20the%20triggering%20signal.

As you rightly pointed out, the sample time cannot be inherited by simscape electrical blocks used in your model. So using them inside triggered subsystems is not possible as this documentation link states - https://www.mathworks.com/help/simscape/ug/limitations.html#brlfdf9-1:~:text=Nonvirtual%20subsystems%20that%20do%20not%20support%20continuous%20sample%20time%20blocks%20(such%20as%20If%20Action%2C%20For%20Iterator%2C%20Function%2DCall%2C%20Triggered%2C%20While%20Iterator%2C%20and%20so%20on)%20cannot%20contain%20Simscape%20blocks..

Have you considered using alternative methods for CPU utilization profiling? You may also use the techniques mentioned in these documentation links-

https://www.mathworks.com/help/ti-c2000/ug/profling-external-xcp-mode.html

https://www.mathworks.com/help/ti-c2000/ug/profiling-on-c2000.html#mw_de546719-4992-4a56-8694-72aff099c0ba

Best,

Raghava

[Jens]

Hi @Raghava S N,

many thanks for the links to alternative profiling methods. I'll try them and see what works best with simscape electrical.

Best,

jens