Time is a technology

code for arduino

https://web.archive.org/web/20120105015729/http://wiki.makerbot.com/mre2

using the makerbot magnetic rotary encoder v2.1 here is the code

#define ENCODER_A_PIN 2
#define ENCODER_B_PIN 3

long position;

void setup()
{   
Serial.begin(19200);   
Serial.println("Started");    
pinMode(ENCODER_A_PIN, INPUT);   
pinMode(ENCODER_B_PIN, INPUT);    
attachInterrupt(0, read_quadrature, CHANGE);
} 


void loop()
{   
Serial.print("Position: ");   
Serial.println(position, DEC);   
delay(1000);
} 


 void read_quadrature(){    // found a low-to-high on channel A  if (digitalRead(ENCODER_A_PIN) == HIGH)  {       // check channel B to see which way    if (digitalRead(ENCODER_B_PIN) == LOW)        position++;    else        position--;  }  // found a high-to-low on channel A  else                                          {    // check channel B to see which way    if (digitalRead(ENCODER_B_PIN) == LOW)        position--;    else        position++;  }}