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
Or you can buy the following kits:
| 1 | × | DIYables STEM V3 Starter Kit (Arduino included) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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Additionally, some links direct to products from our own brand, DIYables .
Additionally, some links direct to products from our own brand, DIYables .
Buy Note: When using multiple servo motors, we recommend the PCA9685 16 Channel PWM Servo Driver Module to save MCU pins and make wiring easier.
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
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
- Open Serial Monitor
- Rotate the rotary encoder
- See the servo motor's rotation
- See the result on Serial Monitor
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
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
Code Explanation
Read the line-by-line explanation in comment lines of source code!
Video Tutorial
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