 ros::NodeHandle nh; // The nodeHandle.
 ros::Subscriber<geometry_msgs::Twist> sub("steer_ctrl", &steerCb); // Set subscribe the motor_driver topic.
 
-void setup() {
+void setup()
+{
   /* Set pins Mode. */
-  for (int i = cw_plus; i < ccw_minus + 1; i++) { // 3: CW+, 4: CW-, 5: CCW+, 6:CCW-
+  for (int i = cw_plus; i < ccw_minus + 1; i++)
+  { // 3: CW+, 4: CW-, 5: CCW+, 6:CCW-
     pinMode(i, OUTPUT);
     digitalWrite(i, LOW); // Default pin status is LOW.
   }

 * @author "Yusuke Doi"
 * @param direction Steer to direction.
 */
void gen_pluse(const char direction, double time) {
  switch (direction) {
  case LEFT: // Task steer left.
    noTone(cw_plus); // Unset tone. If don't running tone, not happen.
    tone(ccw_plus, PULSE_FREQUENCY, time); // Write pulse to CCW pin. turn to CW.

 * @author "Yusuke Doi"
 * @param msg This param is msg object of the motor_driver topic.
 */
void steerCb(const geometry_msgs::Twist& msg)
{
  int time = msg.angular.x * 10;
  if (msg.angular.z < 0 && time > 50) gen_pluse(LEFT, time); // Minus mean CCW or right.
  else if (msg.angular.z > 0 && time > 50) gen_pluse(RIGHT, time); // Plus mean CW or left.
