How does a Servo Motor Work and How to Interface it with ESP32?

At the heart of this project is the SG90 servo motor, which contains a small DC motor, a gear train for reducing speed while increasing torque, and a potentiometer connected to the output shaft for position feedback. Inside the servo is a tiny control circuit that compares the target position commanded by the microcontroller against the actual physical position read by the potentiometer. To control this motor, the ESP32 Development Board generates a Pulse Width Modulation (PWM) signal. Instead of varying voltage, a servo interprets the width of electrical pulses to determine its precise angle—typically, a 1-millisecond pulse moves the shaft to 0 degrees, a 1.5-millisecond pulse centers it at 90 degrees, and a 2-millisecond pulse moves it to 180 degrees. By programming the ESP32 using the Arduino IDE and the Servo.h library, you can easily send these specific pulse trains out through a digital GPIO pin connected to the servo's control wire. Because motors draw sudden bursts of electrical current when they start moving or changing direction, the circuit optionally includes a 470uF to 1000uF electrolytic capacitor bridged across the power rails. This capacitor acts like a tiny temporary reservoir, smoothing out voltage drops and preventing the ESP32 from unexpectedly resetting due to power starvation.