Objective: In this activity you'll learn how to connect a joystick to an Arduino board and use its push button feature to implement a "stop" button for a program that is running. 

The code: The pre-placed code blocks set up pin 13 (the red LED) for output and pin 2 (the joystick's B pin) for input. The code then turns on the red LED and starts a loop that keeps reading the joystick's B pin until it gets a nonzero "high" or "1" signal, indicating that the joystick button was pushed. (The B pin has a "low" or "0" value when not being pushed.) The loop then ends and the final code block turns off the LED.

Connections (see diagram below): The joystick has five pins: Y, X, B, VCC, and GND. Using male-to-female wires, connect the VCC and GND pins to the 5V and one of the GND pins, respectively, in the Power section of the Arduino. Connect the B (button) pin to digital pin 2 on the Arduino. For this activity we don't need the X and Y pins (the blue and green wires). For the LED module (not shown on the diagram), plug in its B, G, and R pins to digital pins 11, 12, and 13, respectively, on the Arduino, with the module's "-" pin going in the GND pin.