Hi Ahmad,
To control the Simulink model using the Arduino, the Arduino needs to send control signals to Simulink. This can be acheived by setting up a serial communication.
Additional you would need to modify your Simulink model setup for Arduino Input by using 'Serial Receive' block and later map the received signals to control the state of switches in your buck-boost circuit.
For more infomation,you can refer to https://www.mathworks.com/help/simulink/supportpkg/arduino_ref/send-and-receive-serial-data-using-arduino-hardware.html
Please note this requires the 'Simulink Support Package for Arduino Hardware': https://www.mathworks.com/help/simulink/supportpkg-arduino.html and the 'Instrument Control Toolbox'.
I hope this helps in getting started.
