Servo

Model = SG90

Servo has only three wires: Positive (Red), Ground (Black) and Signal (White or some other colour)

http://store.iteadstudio.com/images/produce/Robot/Motor_And_Servo/SG-90_Servo/sg90.JPG

Wiring

https://www.arduino.cc/en/uploads/Tutorial/sweep_bb.png

Note that the pin 9 of Arduino Uno Board is connected to the signal input of servo 

 

#include 
 
Servo myservo;  // create servo object to control a servo
                // a maximum of eight servo objects can be created
 
int pos = 0;    // variable to store the servo position
 
void setup()
{
  myservo.attach(9);  // attaches the servo on pin 9 to the servo object
}
 
 
void loop()
{
  for(pos = 0; pos < 180; pos += 1)  // goes from 0 degrees to 180 degrees
  {                                  // in steps of 1 degree
    myservo.write(pos);              // tell servo to go to position in variable 'pos'
    delay(15);                       // waits 15ms for the servo to reach the position
  }
  for(pos = 180; pos>=1; pos-=1)     // goes from 180 degrees to 0 degrees
  {                               
    myservo.write(pos);              // tell servo to go to position in variable 'pos'
    delay(15);                       // waits 15ms for the servo to reach the position
  }
}