Example Code for Arduino-Encoder Pulse Reading

Hardware Preparation

Software Preparation

• Arduino IDE Download Arduino IDE

Wiring Diagram

This tutorial is about Encoder usage. We are using D2&D3 as driving pins, you can select other ones, but it requires at least 1 interrupt pin. (We selected D2, Interrupt 0 in this tutorial).

Other Preparation Work

Notice: attachInterrupt()

If using an Arduino UNO and you want to use interrupt port 0 (Int.0), you need to connect digital pin D2 on the board. The following code is only used in UNO and Mega2560. If you want to use Arduino Leonardo, you should change digital pin D3 instead of digital pin D2.

Sample Code

//The sample code for driving one way motor encoder
const byte encoder0pinA = 2;//A pin -> the interrupt pin 0
const byte encoder0pinB = 3;//B pin -> the digital pin 3
byte encoder0PinALast;
int duration;//the number of the pulses
boolean Direction;//the rotation direction


void setup()
{
  Serial.begin(57600);//Initialize the serial port
  EncoderInit();//Initialize the module
}

void loop()
{
  Serial.print("Pulse:");
  Serial.println(duration);
  duration = 0;
  delay(100);
}

void EncoderInit()
{
  Direction = true;//default -> Forward
  pinMode(encoder0pinB,INPUT);
  attachInterrupt(0, wheelSpeed, CHANGE);
}

void wheelSpeed()
{
  int Lstate = digitalRead(encoder0pinA);
  if((encoder0PinALast == LOW) && Lstate==HIGH)
  {
    int val = digitalRead(encoder0pinB);
    if(val == LOW && Direction)
    {
      Direction = false; //Reverse
    }
    else if(val == HIGH && !Direction)
    {
      Direction = true;  //Forward
    }
  }
  encoder0PinALast = Lstate;

  if(!Direction)  duration++;
  else  duration--;
}

Result

Explanation: Serial data, when the motor forward, the output value> 0, when the motor reverse rotation, digital output <0. The faster the motor speed, the greater the absolute value of number.