FREE SIMULATOR EXAMPLE · BEGINNER

ESP32: Servo Motor + Potentiometer

This example links a potentiometer on GPIO34 to a servo on GPIO13: turn the knob and the horn follows in real time. The loop reads the 12-bit ADC (0 to 4095), maps it to 0-180 degrees, and updates the servo at 50 Hz while the Serial Monitor prints both the raw reading and the angle.

Board	ESP32 DevKit (Xtensa LX6, 240 MHz)
Difficulty	beginner
Category	robotics
Libraries	ESP32Servo
Runs in	Sensbench browser simulator — free, no account

The exact circuit you get when you open this example — already wired, ready to run.

The sketch

// ESP32 — Servo controlled by Potentiometer
// Servo: PWM → D13  |  V+ → 3V3  |  GND → GND
// Pot  : SIG → D34  |  VCC → 3V3  |  GND → GND

#include <ESP32Servo.h>

#define SERVO_PIN 13
#define POT_PIN   34  // input-only GPIO (ADC)

Servo myServo;


void setup() {
  Serial.begin(115200);
  myServo.attach(SERVO_PIN, 500, 2400); // standard servo pulse range
  Serial.println("ESP32 Servo + Pot control");
}

void loop() {
  int raw   = analogRead(POT_PIN);         // 0–4095 (12-bit ADC)
  int angle = map(raw, 0, 4095, 0, 180);
  myServo.write(angle);
  Serial.printf("Pot: %4d  Angle: %3d deg\n", raw, angle);
  delay(20);
}

How it works

A hobby servo expects a pulse every 20 ms, and the pulse width sets the angle. myServo.attach(SERVO_PIN, 500, 2400) hands the pin to the ESP32Servo library with explicit limits — 500 us for 0 degrees, 2400 us for 180 — and from then on the library’s LEDC-backed driver keeps the pulse train running in hardware. write(angle) just changes the width; no timing code of yours is involved.

GPIO34 feeds the ESP32’s 12-bit ADC, so analogRead() returns 0 to 4095 — not the 0 to 1023 an Uno gives you. map(raw, 0, 4095, 0, 180) scales the reading to degrees, and the pair of numbers printed each pass lets you watch the ADC’s last-digit jitter, which is normal analog behavior, not a bug in your wiring.

The delay(20) paces the loop at 50 Hz — the same frame rate the servo speaks. Polling faster accomplishes nothing, because the servo only samples a new command once per frame. This is the tightest sensible coupling between a knob and a horn you can write in fifteen lines.

Before you build it for real

Get the parts

Related examples

FAQ

Why 500 to 2400 microseconds instead of the usual 1000 to 2000?

1000-2000 us is the conservative standard for 0-180 degrees; many servos physically travel further, and 500-2400 squeezes out that extra range. If your servo buzzes or stalls at the ends of the knob, it has hit its mechanical stops — tighten the limits in attach() until the buzzing stops.

Can I use a different pin for the servo?

Any output-capable GPIO works — the library routes the signal through LEDC, which can reach almost any pin. Just avoid the input-only pins 34-39 and the strapping pins. GPIO13 is a safe default, which is exactly why the sketch uses it.