Not getting full range of servo when running from Simulink

Hello, I have a very simple Simulink program to control a servo with my Arduino. The problem is that I'm not getting a full range of the servo. I am using an Adafruit Motor Shield to drive the servo which is a cheap TowerPro. The range I'm getting is 0 to 70. I am using Matlab/Simulink 2019.

Any ideas what could be wrong?

Thank you

Answer 1

[MULI]

Hi @lindula,

I understand that you are getting the limited servo range (0–70°) instead of the typical 0 –180° may be due to incorrect pulse width settings, PWM frequency. You can follow the below steps to resolve this issue:

• Verify that the servo angle input range in the Servo Write block covers 0–180 degrees. https://www.mathworks.com/help/simulink/supportpkg/arduino_ref/servowrite.html
• Many TowerPro servos expect roughly 500 µs for 0° and up to 2400 µs for 180°. If the Adafruit Motor Shield library or the Simulink block uses a narrower pulse range, the servo won’t achieve its full sweep.
• Standard servos use ~50 Hz. Ensure your hardware setup is generating a 20 ms period. A different frequency can reduce travel range.
• Undervoltage or insufficient current can limit servo motion. Make sure you have a stable power source supplying the servo.

By ensuring the correct pulse width range, PWM frequency, and power setup, you should be able to get the full range of motion from your TowerPro servo in Simulink.

Hope this answers your query!