Simulate Arduino Sketches in Modelica

With the Arduino Modelica library you can simulate your circuits and sketches on a virtual Arduino Uno and connect your Modelica models to real-world circuits using the Firmata protocol.

Prerequisites

• Dymola or OpenModelica
• Visual Studio 2015 or later
• CMake

Getting Started

• download the latest release and extract the archive

Simulating a Sketch with Dymola

• in Dymola select File > Load... and open Arduino/package.mo from the extracted files
• open Arduino.Components.ArduinoUno and set the default values for parameters cmake and generator to match your installation, e.g.

model ArduinoUno "Virtual Arduino Uno"

  // ...
  parameter String cmake = "C:\\Program Files\\CMake\\bin\\cmake.exe";
  parameter String generator = "Visual Studio 17 2022";
  // ...

• select File > Save to save your changes
• open Arduino.Examples.Blink
• select the Simulation ribbon and click Simulate to run the simulation
• after the simulation has finished click the Play button in the Animation Control section and watch the LED L blink

Simulating a Sketch with OpenModelica

• in OMEdit select File > Load library and choose the Arduino folder from the extracted files
• open Arduino.Internal.buildSketchOM and set the default values for parameters cmake and generator to match your installation, e.g.

encapsulated function buildSketchOM

  // ...
  input String cmake = "C:/Program Files/CMake/bin/cmake.exe" "Absolute path to the CMake executable";
  input String generator = "Visual Studio 17 2022" "CMake generator to build the Sketch";
  // ...

• select File > Save to save your changes
• open Arduino.Examples.Blink
• select Tools > OpenModelica Compiler CLI and run

Arduino.Internal.buildSketchOM("Blink.ino")

to build the Arduino binary

• select Simulation > Simulate to run the simulation
• in the View toolbar click on the gears icon (Diagram Window)
• in the Variables Browser click the play button and watch the LED L blink

Simulate your own Sketch

To simulate your sketch MySketch you have to perform the following steps.

• save your sketch as Arduino/Resources/Sketches/MySketch.ino
• add the block Arduino.Components.ArduinoUno to your model
• double-click the block and set the parameter sketch to "MySketch.ino"

In Dymola:

• click Translate to re-translate the model when the sketch has changed

In OpenModelica:

• run Arduino.Internal.buildSketchOM("MySketch.ino") in the Compiler CLI when the sketch has changed

Limitations

• currently you can use only one instance of ArduinoUno in your Modelica model

• the whole Arduino API is supported except for the following functions

  • analogReadResolution()
  • analogWriteResolution()
  • shiftOut()
  • shiftIn()
  • isWhitespace()
  • Serial (print(), println() and write() are supported)
  • Stream
  • Keyboard
  • Mouse

Arduino Libraries

The following libraries are included and can be used directly.

Name	Description
Servo.h	Servo library to control RC (hobby) servo motors
PID_v1.h	PID controller library for Arduino

To use an external library in your sketch copy its header files (*.h) and source files (*.cpp) to the Libraries folder. If the library contains .cpp files you have to add them to the Arduino project by dragging them from the Libraries folder in the file browser onto the Source Files folder in the solution explorer.

How it works

The ArduinoUno model is driven by an ExternalObject that contains the compiled sketch and an implementation of the Arduino API. The external object is synchronized at every sample step with the Modelica model.

When a model that contains the ArduinoUno block is translated the external object is automatically re-built through the preInstantiate=Arduino.Internal.buildSketch() directive in its annotation.

This function writes a new Sketch.cpp to Arduino/Resources/Source/Arduino that includes the sketch currently selected in the ArduinoUno component, calls CMake to generate the Visual Studio Solution, and builds the shared library Arduino/Resources/Library/{win32|win64}/ModelicaArduino.dll that contains the implementation of the external object.

Debugging a Sketch

• translate and simulate the model you want to debug
• open Arduino/Resources/Source/Arduino/Win32/Arduino.sln (or Arduino/Resources/Source/Arduino/x64/Arduino.sln if Advanced.CompileWith64 = 2)
• select Debug as configuration
• open the settings of the ModelicaArduino project and under Debug set Command to dymosim.exe and Working Directory to your current Dymola working directory
• open the sketch in Visual Studio and set a breakpoint
• start debugging

Copyright and License

Copyright © 2022 Dassault Systèmes. The code is licensed GPLv3, the documentation CC BY-SA 4.0.