Using 'SIMULINK Support Package for Arduino Hardware' like 'LabVIEW'

Hello,

I am working on implementing LabVIEW-like functionality using the <SIMULINK Support Package for Arduino Hardware> and uploading it to an Arduino.

My goal is to implement hard constraints in Simulink (as I understand that Simulink's default behavior is soft constraint).

Here's my understanding of the concepts:

Hard constraint: In a 1kHz loop, if a loop started at time 't ms' exceeds 1ms, it stops processing the current sensor value (t ms) and moves to the next sensor value at 't+1 ms'.

Soft constraint: If the loop exceeds 1ms, it completes processing the current loop(t ms) and skips the next cycle(t+1 ms), moving to the loop with value at 't+2 ms'.

In LabVIEW, I understand that the `Deadline` command allows for implementing hard constraints.(Link: https://www.ni.com/docs/en-US/bundle/labview-api-ref/page/structures/timed-loop.html)

I tried to achieve this using `tic` and `toc` in the following code, but it failed to upload on the Arduino board

%% matlab code %%

function [num, y] = fcn(a,b)

persistent t

if isempty(t)

t = 0;

end

t = t+1;

num = t;

startTime = tic;

A = rand(a,b);

y = toc(startTime);

end

%%

Does anyone know a solution to this problem?

Thank you in advance.

Answer 1

[UDAYA PEDDIRAJU]

Hi 순호 권,

To implement hard constraints in Simulink for an Arduino using the Simulink Support Package, you can follow these steps:

Use Rate Transition Blocks: Ensure data consistency and timing by using Rate Transition blocks for data transfer between different rates.

Configure Solver Settings:

• Set your model to use a fixed-step solver for deterministic execution.
• Choose a step size that corresponds to your desired loop frequency (e.g., 1ms for 1kHz).

Use a Real-Time Task:

• Create a Function-Call Subsystem or a Triggered Subsystem to execute tasks at a specified rate.
• If available, use a Hardware Interrupt block to trigger execution based on external events.

Monitor Execution Time:

• Implement a mechanism to measure execution time within the loop, similar to "tic" and 'toc' in MATLAB.
• Compare execution time against your 1ms deadline, and implement logic to skip processing if the deadline is exceeded.

Generate and Deploy Code:

• Use Simulink Coder to generate optimized code for real-time performance.
• Deploy the generated code to the Arduino using the Simulink Support Package.

Example Implementation:

Create a Function-Call Subsystem:

• Use a Clock block to measure elapsed time.
• Compare elapsed time with the 1ms deadline using a Compare To Constant block.
• Use a Switch block to decide whether to process current data or skip to the next cycle.

Model Configuration:

• Set the solver to a fixed-step size of 0.001 seconds (1ms).
• Use a Timer block (if available) to ensure precise execution intervals.

Deploy to Arduino:

• Use the "Deploy to Hardware" feature to upload your model to the Arduino.

[순호 권]

Thank you for your response.

I have a few questions regarding your answer, which I'd like to clarify:

Use a Real-Time Task:

Q1. In the context of using a Real-Time Task, what exactly is the Hardware Interrupt block that you mentioned?

Generate and Deploy Code:

Q2. When you referred to using Simulink Coder in the "Generate and Deploy Code" section, were you suggesting that I should use Embedded Coder to upload the program to the Arduino?

I look forward to your response.

Thank you.