int speedPin = 5;
int dir1 = 4;
int dir2 = 3;
int mSpeed;
int dur = 100;
int dur2 = 5000;

int jPin = A1;
int jVal;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(speedPin, OUTPUT);
  pinMode(dir1, OUTPUT);
  pinMode(dir2, OUTPUT);
  pinMode(jPin, INPUT);
}

void loop() {
  //counter clockwise
  jVal = analogRead(jPin);
  Serial.println(jVal);

  if(jVal < 512){
    digitalWrite(dir1, LOW);
    digitalWrite(dir2, HIGH);
    mSpeed=-255./512. * jVal + 255.;
    analogWrite(speedPin, mSpeed);
  }

  if(jVal >= 512){
     digitalWrite(dir1, HIGH);
    digitalWrite(dir2, LOW);
    mSpeed=-255./512. * jVal + 255.;
    analogWrite(speedPin, mSpeed);

  }
}