Keyboard Teleop settings.

edit

I write a program in arduino. i want to do the same with ros-keyboard_teleop. can sombody guide me ?any tutorial link.

void setup() 
{
  pinMode(24, OUTPUT);
  pinMode(25, OUTPUT);
  Serial.begin(9600);
}


void loop() 
{ 
  if (Serial.available())
  {
    char data = Serial.read();

    if(data == 'i')
    {
      digitalWrite(24, LOW);
      digitalWrite(25, HIGH);
     Serial.println("reverse");
    }
    else if(data == 'j')
    {
      digitalWrite(24, HIGH);
      digitalWrite(25, LOW);
      Serial.println("forward");

    }
   else
    {
      digitalWrite(24,LOW);
      digitalWrite(25,LOW);
     Serial.println("stop"); 
    }}}

i did a program. but i think there is a problem with

else if (y = vel.linear.y - 1.0) can you check my code and tell me where is the problem?

   #include <ros.h>
    #include <geometry_msgs/Twist.h>
    float x;
    float y; 
    ros::NodeHandle nh;

    void velCallback(  const geometry_msgs::Twist& vel)
    {
       if (x = vel.linear.x - 1.0) //Forward move.
          {
          digitalWrite(24, LOW);
          digitalWrite(23, HIGH);
          }
    else if (y = vel.linear.y - 1.0)   //Backward move
    {
          digitalWrite(24, HIGH);
          digitalWrite(23, LOW);
    }
    else 
    {
        digitalWrite(24, LOW);     //STOP
          digitalWrite(23, LOW);
    }
        }

ros::Subscriber<geometry_msgs::Twist> sub("cmd_vel" , velCallback);

void setup() 
{
     nh.initNode();
     nh.subscribe(sub);
}

void loop() 
{
     nh.spinOnce();
     delay(10);
}