const int encoderA_pin = 2;  
const int encoderB_pin = 3;  

volatile int encoderPosition = 0;  
void encoderA_ISR() {
  // Determine direction by checking Channel B
  Serial.print("channle a :");
  Serial.print(digitalRead(encoderA_pin));
  Serial.print(" channle b :");
  Serial.println(digitalRead(encoderB_pin));

  if (digitalRead(encoderA_pin) == digitalRead(encoderB_pin)) {
    encoderPosition++;  // Clockwise
  } else {
    encoderPosition--;  // Counterclockwise
  }
}

void setup() {
  Serial.begin(9600);
  
  pinMode(encoderA_pin, INPUT);
  pinMode(encoderB_pin, INPUT);

  attachInterrupt(digitalPinToInterrupt(encoderA_pin), encoderA_ISR, CHANGE);
  attachInterrupt(digitalPinToInterrupt(encoderB_pin), encoderA_ISR, CHANGE);
}

void loop() {
  Serial.print("Position: ");
  Serial.println(encoderPosition);
  delay(2000);
}


/*
 #define outputA 6
 #define outputB 7

 int counter = 0; 
 int aState;
 int aLastState;  

 void setup() { 
   pinMode (outputA,INPUT);
   pinMode (outputB,INPUT);
   
   Serial.begin (9600);
   // Reads the initial state of the outputA
   aLastState = digitalRead(outputA);   
 } 

 void loop() { 
   aState = digitalRead(outputA); // Reads the "current" state of the outputA
   // If the previous and the current state of the outputA are different, that means a Pulse has occured
   if (aState != aLastState){     
     // If the outputB state is different to the outputA state, that means the encoder is rotating clockwise
     if (digitalRead(outputB) != aState) { 
       counter ++;
     } else {
       counter --;
     }
     Serial.print("Position: ");
     Serial.println(counter);
   } 
   aLastState = aState; // Updates the previous state of the outputA with the current state
 }
*/