Arduino - Rotary Encoder - Servo Motor

In this tutorial, We are going to learn how to program Arduino to rotate a servo motor according to the rotary encoder's output value.

Hardware Required

1×Arduino UNO or Genuino UNO
1×USB 2.0 cable type A/B
1×Servo Motor
1×Rotary Encoder
1×Breadboard
1×Jumper Wires
1×(Optional) 9V Power Adapter for Arduino
1×(Recommended) Screw Terminal Block Shield for Arduino Uno
1×(Optional) Transparent Acrylic Enclosure For Arduino Uno

Or you can buy the following sensor kit:

1×DIYables Sensor Kit 30 types, 69 units
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About Servo Motor and Rotary Encoder

If you do not know about servo motor and rotary encoder (pinout, how it works, how to program ...), learn about them in the following tutorials:

Wiring Diagram

Arduino Rotary Encoder Servo Motor Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Arduino Code

/* * Created by ArduinoGetStarted.com * * This example code is in the public domain * * Tutorial page: https://arduinogetstarted.com/tutorials/arduino-rotary-encoder-servo-motor */ #include <Servo.h> #define CLK_PIN 2 #define DT_PIN 3 #define SW_PIN 4 #define SERVO_PIN 9 #define DIRECTION_CW 0 // clockwise direction #define DIRECTION_CCW 1 // counter-clockwise direction int counter = 0; int direction = DIRECTION_CW; int CLK_state; int prev_CLK_state; Servo servo; // create servo object to control a servo void setup() { Serial.begin(9600); // configure encoder pins as inputs pinMode(CLK_PIN, INPUT); pinMode(DT_PIN, INPUT); // read the initial state of the rotary encoder's CLK pin prev_CLK_state = digitalRead(CLK_PIN); servo.attach(SERVO_PIN); // attaches the servo on pin 9 to the servo object servo.write(0); } void loop() { // read the current state of the rotary encoder's CLK pin CLK_state = digitalRead(CLK_PIN); // If the state of CLK is changed, then pulse occurred // React to only the rising edge (from LOW to HIGH) to avoid double count if (CLK_state != prev_CLK_state && CLK_state == HIGH) { // if the DT state is HIGH // the encoder is rotating in counter-clockwise direction => decrease the counter if (digitalRead(DT_PIN) == HIGH) { counter--; direction = DIRECTION_CCW; } else { // the encoder is rotating in clockwise direction => increase the counter counter++; direction = DIRECTION_CW; } Serial.print("DIRECTION: "); if (direction == DIRECTION_CW) Serial.print("Clockwise"); else Serial.print("Counter-clockwise"); Serial.print(" | COUNTER: "); Serial.println(counter); if (counter < 0) counter = 0; else if (counter > 180) counter = 180; // sets the servo angle according to the counter servo.write(counter); } // save last CLK state prev_CLK_state = CLK_state; }

Quick Steps

  • Connect Arduino to PC via USB cable
  • Open Arduino IDE, select the right board and port
  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to Arduino
Arduino IDE Upload Code
  • Open Serial Monitor
  • Rotate the rotary encoder
  • See the servo motor's rotation
  • See the result on Serial Monitor
COM6
Send
DIRECTION: Clockwise | COUNTER/ANGLE: 19 DIRECTION: Clockwise | COUNTER/ANGLE: 26 DIRECTION: Clockwise | COUNTER/ANGLE: 34 DIRECTION: Clockwise | COUNTER/ANGLE: 46 DIRECTION: Clockwise | COUNTER/ANGLE: 53 DIRECTION: Counter-clockwise | COUNTER/ANGLE: 46 DIRECTION: Counter-clockwise | COUNTER/ANGLE: 34 DIRECTION: Counter-clockwise | COUNTER/ANGLE: 26 DIRECTION: Counter-clockwise | COUNTER/ANGLE: 16 DIRECTION: Counter-clockwise | COUNTER/ANGLE: 06
Autoscroll Show timestamp
Clear output
9600 baud  
Newline  

Code Explanation

Read the line-by-line explanation in comment lines of source code!

Video Tutorial

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