How to use a Rotary Encoder Button

What is a ServoRotary Motor?Encoder Button?

A servorotary motorencoder button is an input device that combines: a Rotary encoder — to detect rotational direction (clockwise/counterclockwise) and steps and a Push button — to detect when the knob is pressed down. This component is smaller in size and significantly cheaper than a regular rotary actuatorencoder.

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Types of Common RC Servo Motors

Servo Type	Rotation Range	Control Type	Common Use
Regular (Standard) Servo	0°–180° (sometimes 270°)	Angular position (PWM)	Arms, steering, gimbals
Continuous Rotation Servo	360° (infinite)	Speed & direction (PWM)	Wheels, drive systems
Mini / Micro Servo	Depends on type (limited or continuous)	Same as regular or continuous	Small robots, drones, model planes

Using a PWM Driver

You may come across many online tutorials that show how to control servo motors directly without a PWM driver. While this method is possible, it’s not the most reliable—especially when working with multiple servos. Sooner or later, you’re likely to run into issues, often related to power management and signal stability.

For this reason, in this tutorial, we’ll be using the Seeed Studio 16-channel PWM driver for more stable and scalable control. You can also use other similar PWM driver boards depending on your needs.

Wiring

1. 5VTop Power2 Supply on the Left:Pins:
   • one +pin to 5VD4
   • one -pin to GND
2. i2CBottom to3 Arduino on the Right:Pins:
   • GNDRight Pin to D3
   • middle pin to GND
   • 5VLeft Pin to 5V
   • SCL to SCL
   • SDA to SDA
3. Servo to PWM Out:
   • Plug in the servo, where the black wire goes to the GNDD2

Library

Grove-16-Channel_PWM_Driver-PCA9685EncoderStepCounter library will be used.

We have a tutorial on how to install a library here.

Getting started - Regular Servo

This code is getting the eight servo motors to rotate to 0 degrees and then 90 degrees, one by one.

#include "PCA9685.h"
#include <Wire.EncoderStepCounter.h>
 
ServoDriverconst servo;int pin1 = 2;
const int pin2 = 3;
 
// Create encoder instance:
EncoderStepCounter encoder(pin1, pin2);
 
// encoder previous position:
int oldPosition = 0;
 
const int buttonPin = 4;    // pushbutton pin
int lastButtonState = LOW;  // last button state
int debounceDelay = 5;      // debounce time for the button in ms
 
 
void setup() {
  // join I2C bus (I2Cdev library doesn't do this automatically)
    Wire.begin();
    Serial.begin(9600);
  servo.init(0x7f)// Initialize encoder
  encoder.begin();
  // Initialize interrupts
  attachInterrupt(digitalPinToInterrupt(pin1), interrupt, CHANGE);
  attachInterrupt(digitalPinToInterrupt(pin2), interrupt, CHANGE);
  // set the button pin as an input_pullup:
  pinMode(buttonPin, INPUT_PULLUP);
}
 
void loop() {
  // Driveif 8you're servosnot using interrupts, you need this in turnsthe forloop:
  (encoder.tick();
 
  // read encoder position:
  int iposition = 1;encoder.getPosition();
  i// <read 9;the i++)pushbutton:
  int buttonState = digitalRead(buttonPin);
  //  // if the button has changed:
  if (buttonState != lastButtonState) {
    servo.setAngle(i,// 0)debounce the button:
    delay(debounceDelay);
    delay(1000)// if button is pressed:
    if (buttonState == LOW) {
      Serial.print("you pressed on position: ");
      servo.setAngle(i, 90);
        delay(1000)Serial.println(position);
    }
  }
  

//

Gettingsave startedcurrent -button Continuousstate Servo

for

Sincenext time through the loop: lastButtonState = buttonState; // reset the encoder after 24 steps: if (position % 24 == 0) { encoder.reset(); position = encoder.getPosition(); } // if there's been a continuouschange, servoprint isit: controlledif by(position a!= pulse,oldPosition) the{ ‘degree’Serial.println(position); valuesoldPosition work= differently.position; Values} like} 0,// 90,Call andtick 180on don’tevery representchange angles; instead, they typically control rotation direction and speed — for example, 0 means full speed clockwise, 90 means stop, and 180 means full speed counterclockwise.

The below code is getting the servo motor 1 rotates clockwise for 1 second and stop for 1 second.

#include "PCA9685.h"
#include <Wire.h>

ServoDriver servo;interrupt
void setup(interrupt() {
  // join I2C bus (I2Cdev library doesn't do this automatically)
    Wire.begin(encoder.tick();
    Serial.begin(9600);
    servo.init(0x7f);
    
    //Most continuous servo motors' pulse width is 900-2100
    servo.setServoPulseRange(900,2100,180);
}

void loop()
{
    // Drive 8 servos in turns
        servo.setAngle(1, 0);
        delay(1000);
        servo.setAngle(1, 90);
        delay(1000);
}