Example Code for Arduino-One Way Motor Encoder

Wiring Diagram

Diagram for UNO

Interrupt Port with Different Board

Other Preparation Work

Note: attachInterrupt()

For example,with UNO board, you want to use interrupt port 0(int.0). You should connect digital pin 2 with the board. So, the following code is only used in UNO and Mega2560. If you want to use Leonardo or Romeo, you should change digital pin 3 instead of digital pin 2.

See the link for detail http://arduino.cc/en/Reference/AttachInterrupt

Sample Code

//The sample code for driving one way motor encoder
const byte encoder0pinA = 2;//A pin -> the interrupt pin 0
const byte encoder0pinB = 4;//B pin -> the digital pin 4
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--;
}

Warning: Do not screw too far into the mounting holes as the screws can hit the gears. Manufacturer recommends screwing no further than 3mm (1/8") into the screw hole.

See the link for detail http://arduino.cc/en/Reference/AttachInterrupt