1. What is a Joystick?

A joystick is an input device that allows the user to enter directional information--up, down, left, right--by moving the joystick in the intended direction. Many joysticks also can work as a button by pressing down on it. Joysticks and similar devices are often used in video game controllers. We will learn how to use a joystick to control an LED and move a Linkbot robot in the activities that follow this lesson.

2. The Joystick's Pins

The joystick has five pins: Y, X, B, VCC, and GND.

The purpose of each pin is:

• Y pin: provides input for motion in the y direction (up and down, or forward and backward)
• X pin: provides input for motion in the x direction (left and right)
• B pin: provides input for the joystick button (when pressed)
• VCC pin: voltage connection to provide power to the joystick
• GND pin: ground connection

3. Connecting the Joystick to an Arduino Board

We will use the setup shown above to connect the joystick to an Arduino board:

1. Use male-to-female wires to connect the VCC and GND pins to the 5V pin and one of the GND pins, respectively, in the Power section of the Arduino.

2. Connect the B (button) pin to digital pin 2 on the Arduino.

3. Connect the Y pin to analog pin A0.

4. Connect the X pin to analog pin A1.
 

4. Joystick Pin Values

Note that the joystick button (B) is connected to a digital pin on the Arduino, because the button is either on (pushed down) or off (HIGH voltage when on, LOW voltage when off).

But the Y and X pins are connected to analog pins, because the joystick covers a range of values as it is moved forward and backward, or left and right. 

• The Y value that the joystick sends to the Arduino ranges from 0 (joystick pushed completely backward) to 1023 (joystick pushed completely forward).
• The X value that the joystick sends to the Arduino ranges from 0 (joystick pushed completely left) to 1023 (joystick pushed completely right).
• When the joystick is in its central or neutral position, the Y value and the X value are each 512 (halfway between 0 and 1023). But in practice the joystick calibration may be slightly off, so that the neutral value is close to but not exactly equal to 512.