HOW to Use Rotary Encoder on Raspberry Pi with ESP32

Overview

In this kit, there is a Keyestudio rotary encoder, dubbed as switch encoder. It is applied to automotive electronics, multimedia audio, instrumentation, household appliances, smart home, medical equipment and so on.

In the experiment, it it used for counting. When we rotate the rotary encoder clockwise, the set data is up 1; if you rotate it anticlockwise, the set data falls by 1; and when the middle button is pressed, the value will be show in the serial monitor.

Working Principle

The incremental encoder converts the displacement into a periodic electric signal, and then converts this signal into a counting pulse, and the number of pulses indicates the size of the displacement. This module mainly uses 20-pulse rotary encoder components. It can calculate the number of pulses output during clockwise and reverse rotation. There is no limit to count rotation. It resets to the initial state, that is, starts counting from 0.

Components

Connection Diagram

Test Code

//**********************************************************************************
/*  
 * Filename    : Encoder
 * Description : Rotary encoder module counting.
 * Auther      : http//www.keyestudio.com
*/
//Interfacing Rotary Encoder with Arduino
//Encoder Switch -> pin 27
//Encoder DT -> pin 14
//Encoder CLK -> pin 12

int Encoder_DT  = 14;
int Encoder_CLK  = 12;
int Encoder_Switch = 27;

int Previous_Output;
int Encoder_Count;

void setup() {
  Serial.begin(9600);

  //pin Mode declaration
  pinMode (Encoder_DT, INPUT);
  pinMode (Encoder_CLK, INPUT);
  pinMode (Encoder_Switch, INPUT);

  Previous_Output = digitalRead(Encoder_DT); //Read the inital value of Output A
}

void loop() {
  //aVal = digitalRead(pinA);

  if (digitalRead(Encoder_DT) != Previous_Output)
  {
    if (digitalRead(Encoder_CLK) != Previous_Output)
    {
      Encoder_Count ++;
      Serial.println(Encoder_Count);
    }
    else
    {
      Encoder_Count--;
      Serial.println(Encoder_Count);
    }
  }

  Previous_Output = digitalRead(Encoder_DT);

  if (digitalRead(Encoder_Switch) == 0)
  {
    delay(5);
    if (digitalRead(Encoder_Switch) == 0) {
      Serial.println("Switch pressed");
      while (digitalRead(Encoder_Switch) == 0);
    }
  }
}
//**********************************************************************************

Code Explanation

Set CLK to GPIO12 and DAT to GPIO14.

This code is set well in the library file. When CLK descends, read the voltage of DAT, when DAT is a HIGH level, the value of the rotary encoder is added by 1; when DAT is a LOW level, the value of the rotary encoder is cut down 1.

Set the pin of the button(GPIO27) to LOW and print.

Test Result

Connect the wires according to the experimental wiring diagram, compile and upload the code to the ESP32. After uploading successfully，we will use a USB cable to power on. Open the serial monitor and set baud rate to 9600.

We need to press the reset button on the ESP32, then rotate the knob on the rotary encoder clockwise, the displayed data will rise; on the contrary, in anticlockwise way, the data will decrease. Equally, press the button on the rotary encoder, “Switch pressed” will be shown.