Arduino Servo Control Advanced

The Adafruit PWMServoDriver library controls many servos through an external PCA9685 board using I²C, offloading timing from the microcontroller.

The standard Servo library directly drives servos from Arduino PWM pins but supports fewer motors and uses CPU timing.

PCA9685 = multi‑servo hardware control;

Servo = simple, direct.

How PWM moves a servo

A servo doesn’t rotate freely — its internal circuit reads a PWM signal: a steady series of repeating pulses.

Each pulse’s length (width) tells the servo what angle to move to.

• Pulse every 20 ms → frequency ≈ 50 Hz.

• High (ON) time varies:

  • ≈ 1.0 ms → 0 degrees

  • ≈ 1.5 ms → 90 degrees

  • ≈ 2.0 ms → 180 degrees

Example Code for Servo Control