encoder

int encoder = 11;

int curr_state;
int prev_state;
double curr_time;
double prev_time;
int time_change;
int counter = 0;
double speed;


// in3 and in4 are used to define direction of right motor
const int in3 = 5;  
const int in4 = 4;  
// enB is used for PWM to change speed of right motor
const int enB = 6; 

const int in1 = 19;
const int in2 = 18;
const int enA = 2;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  delay(1000);
  Serial.println("start");

    // motor A - setting pin mode to OUTPUT
  pinMode(in3,OUTPUT);
  pinMode(in4,OUTPUT);
  pinMode(enB,OUTPUT);

  pinMode(encoder, INPUT_PULLUP);
  prev_state = digitalRead(encoder);
  Serial.println("first prev state ");
  Serial.println(prev_state);

  prev_time = 0;
}

void loop() {
  // put your main code here, to run repeatedly:
  //Serial.println("working");
  digitalWrite(in3, HIGH);
  digitalWrite(in4, LOW);
  analogWrite(enB, 200);

  //Serial.println("prev state ");
  //Serial.println(prev_state);
  curr_time = millis();
  curr_state = digitalRead(encoder);
  Serial.println("curr state ");
  Serial.println(curr_state);

  if (curr_state != prev_state) {
    counter++;
  }
  
  //Serial.print("counter ");
  //Serial.println(counter);
  if (counter == 480){
    Serial.print("counter ");
    Serial.println(counter);
    //Serial.print("current ");
    //Serial.println(curr_time);
    //Serial.print("previous ");
    //Serial.println(prev_time);
    time_change = curr_time - prev_time;
    Serial.print("Time change ");
    Serial.println(time_change);
    speed = 6.5 * PI / (time_change / 1000);
    Serial.print("Buggy speed ");
    Serial.println(speed);
    counter = 0;
    prev_time = curr_time;
  }


prev_state = curr_state;

}