*Help Desparately Needed**-Simulink to control servo motor with Arduino

I am working on a project that needs to use an Arduino Mega MCU to take an analog input, use a comparator block to make a decision, then control a servo motor based on the comparator's output. I am confused as to how to make this happen. The servo requires 1000 - 2000 microseconds PWM to move, with 1500 being neutral. The Arduino PWM block only asks for a number between 0-255, which corresponds to a duty cycle. The Arduino Servo Write (Standard)only asks for a pin number and moves the motor based on the input. Which one should I use?

Thank you very much in advance for all your expertise and help! My senior design project depends on it. -Kristi