int encoder_pin = 2; // pulse output from the module

int pulses;

unsigned long timeold;

int pinState = 0;

int lastpinState = 0;

int laju;

int turn;



void setup()

{

Serial.begin(9600);

pinMode(encoder_pin, INPUT);

attachInterrupt(0, counter, FALLING);

pulses = 0;

timeold = 0;

}

void loop()

{

if (millis() – timeold >= 500) {

detachInterrupt(0);

laju=(pulses)*(6.28/10000)*1000*60; //number pulses in 500ms with 20 hole disk

turn=(pulses)/10;

Serial.print(pulses);

Serial.print(” pulses/500ms “);

Serial.print(laju);

Serial.print(” rpm”);

Serial.print(” “);

Serial.print(turn);

Serial.println(” turn/second”);

timeold = millis();

pulses = 0;

attachInterrupt(0, counter, FALLING);



}

}

void counter()

{

pinState = digitalRead(encoder_pin);

if (pinState != lastpinState) {

if (pinState == HIGH) {

pulses++;

}

lastpinState = pinState;

}

}