I needed to make this work for a project and finally did by following the S Function Builder tutorial that was posted Here: http://www.mathworks.com/matlabcentral/answers/74044-s-function-builder-help
I've also made an S Function with this same process for the ADS1115 I2C 16 bit ADC using the adafruit ADS1015 library but I'll post that later.
Guillermo (2019). Arduino S Function for MPC4725 I2C DAC (https://www.mathworks.com/matlabcentral/fileexchange/41906-arduino-s-function-for-mpc4725-i2c-dac), MATLAB Central File Exchange. Retrieved .
Uploaded a screenshot.