This project intends to show the benefits of using MATLAB/Simulink to generate code for Arduino hardware. The project includes a Simulink library containing blocks for usage of several common Arduino modules (f. i. LC-Display) and examples that show how they can be used.
Have a look at the the Wiki for more information and HowTos.
The QuickStart Guide: LCD gives you a brief impression of how easily an LiquidCrystal-Display can be used in a Simulink model that runs on an Arduino board using the "Arduino Drivers" library from this project.