i tried several sketches but the one that works for me is :
/*
(Copy and paste)
Rotary encoder decoding using two interrupt lines.
Most Arduino boards have two external interrupts,
numbers 0 (on digital pin 2) and 1 (on digital pin 3).
Program sketch is for SparkFun Rotary Encoder sku: COM-09117
Connect the middle pin of the three to ground.
The outside two pins of the three are connected to
digital pins 2 and 3
*/
volatile int number = 0; // Testnumber, print it when it changes value,
// used in loop and both interrupt routines
int oldnumber = number;
volatile boolean halfleft = false; // Used in both interrupt routines
volatile boolean halfright = false;
void setup(){
Serial.begin(9600);
pinMode(2, INPUT);
digitalWrite(2, HIGH); // Turn on internal pullup resistor
pinMode(3, INPUT);
digitalWrite(3, HIGH); // Turn on internal pullup resistor
attachInterrupt(0, isr_2, FALLING); // Call isr_2 when digital pin 2 goes LOW
attachInterrupt(1, isr_3, FALLING); // Call isr_3 when digital pin 3 goes LOW
}
void loop(){
if(number != oldnumber){ // Change in value ?
Serial.println(number); // Yes, print it (or whatever)
oldnumber = number;
}
}
void isr_2(){ // Pin2 went LOW
delay(1); // Debounce time
if(digitalRead(2) == LOW){ // Pin2 still LOW ?
if(digitalRead(3) == HIGH && halfright == false){ // -->
halfright = true; // One half click clockwise
}
if(digitalRead(3) == LOW && halfleft == true){ // <--
halfleft = false; // One whole click counter-
number--; // clockwise
}
}
}
void isr_3(){ // Pin3 went LOW
delay(1); // Debounce time
if(digitalRead(3) == LOW){ // Pin3 still LOW ?
if(digitalRead(2) == HIGH && halfleft == false){ // <--
halfleft = true; // One half click counter-
} // clockwise
if(digitalRead(2) == LOW && halfright == true){ // -->
halfright = false; // One whole click clockwise
number++;
}
}
}
i found it here : http://home.online.no/~togalaas/rotary_encoder/
just for other ones who have troubles with this. i am solved 