#define outputA 6
#define outputB 7
 int counter = 0; 
 int aState;
 int aLastState; 
 float jarak; 
 int speed;
 unsigned long newtime;
 unsigned long oldtime = 0;

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

 void loop() { 
   newtime= millis();
   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("Jarak: ");
     jarak=map(counter,0,40,0,31.41);
     Serial.print(jarak);
     Serial.println(" cm");
     speed=jarak*1000/(newtime-oldtime);
     Serial.print("Speed: ");
     Serial.println(speed);
     oldtime = newtime;
     
   } 
 aLastState = aState; // Updates the previous state of the outputA with the current state
 }