How to use Rotary Encoder with Arduino
In this post, we will learn How to use Rotary Encoder with Arduino. We will be displaying the encoded value both in clockwise and anti-clockwise directions in numbers with a sign.
A rotary encoder, also called a shaft encoder, is an electro-mechanical device that converts the angular position or motion of a shaft or axle to analog or digital output signals. There are two main types of rotary encoder: absolute and incremental. The output of an absolute encoder indicates the current shaft position, making it an angle transducer. The output of an incremental encoder provides information about the motion of the shaft, which typically is processed elsewhere into information such as position, speed, and distance.
To learn about Rotary Encoder and its types with application, advantage, and working visit here:
Components Required:
| S.N. | Components Name | Quantity | Purchase Links |
|---|---|---|---|
| 1 | Arduino UNO Board | 1 | Amazon | AliExpress |
| 2 | Rotary Encoder | 1 | Amazon | AliExpress |
| 3 | 16x2 LCD Display | 1 | Amazon | AliExpress |
| 4 | Potentiometer 10K | 1 | Amazon | AliExpress |
| 5 | Connecting Wires | 10 | Amazon | AliExpress |
| 6 | Breadboard | 1 | Amazon | AliExpress |
Circuit Diagram & Connection:
The circuit diagram below is a simple demonstration of how to use Rotary Encoder with Arduino. Assemble the same circuit on breadboard or PCB.
How Rotary Encoder Works?
The encoder has a disk with evenly spaced contact zones that are connected to the common pin C and two other separate contact pins A and B, as illustrated below.
When the disk will start rotating step by step, pins A and B will start making contact with the common pin and the two square wave output signals will be generated accordingly.
Any of the two outputs can be used for determining the rotated position if we just count the pulses of the signal. However, if we want to determine the rotation direction as well, we need to consider both signals at the same time.
We can notice that the two output signals are displaced at 90 degrees out of phase from each other. If the encoder is rotating clockwise the output A will be ahead of output B.
So if we count the steps each time the signal changes, from High to Low or from Low to High, we can notice at that time the two output signals have opposite values. Vice versa, if the encoder is rotating counter-clockwise, the output signals have equal values. So considering this, we can easily program our controller to read the encoder position and the rotation direction.
Source Code/Program:
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#include <LiquidCrystal.h> LiquidCrystal lcd(12, 11, 5, 4, 3, 2); #define outputA 6 #define outputB 7 int counter = 0; int aState; int aLastState; void setup() { pinMode (outputA,INPUT); pinMode (outputB,INPUT); Serial.begin (9600); lcd.begin(16,2); // Reads the initial state of the outputA aLastState = digitalRead(outputA); } void loop() { aState = digitalRead(outputA); // Reads the "current" state of the outputA // If the previous and the current state of the outputA are different, that means a Pulse has occured if (aState != aLastState){ // If the outputB state is different to the outputA state, that means the encoder is rotating clockwise if (digitalRead(outputB) != aState) { counter ++; lcd.clear(); } else { counter --; lcd.clear(); } Serial.print("Position: "); Serial.println(counter); lcd.setCursor(0, 0); lcd.print("Position: "); lcd.setCursor(10, 0); lcd.print(counter); } aLastState = aState; // Updates the previous state of the outputA with the current state } |
Video Tutorial & Explanation:
