Wikijunior:Raspberry Pi/Raspberry Pi Python GPIO Zero Buzz Wire Game

Tutorial by David Pride
Public Domain 26 Oct 2016
www.cotswoldjam.org

This tutorial will cover building your own fairground-style 'buzz wire' game! You will need speakers or headphones to use this tutorial.

The Kit

In your bag you will find the following components:

• ×5 M2F jumper leads
• ×1 220 Ω (red red brown) resistor
• ×1 LED
• ×1 30 cm (~12 inches) bell wire
• ×1 10 cm (~4 inches) bell wire
• ×1 mini-breadboard

Putting it together

Step 1: Take 1 jumper lead and attach it to J6 on the breadboard and pin 7 (GPIO 4) on the Pi.

Step 2: Take 1 jumper lead and attach it to J1 on the breadboard and pin 6 (GND) on the Pi.

Step 3: Take the resistor and insert it into holes H1 and H5 on the breadboard – it doesn’t matter which way round this goes. LEDs are really greedy and will take all the power they can, which could damage the Pi. We use this resistor to limit the power the LED can draw from the Pi.

Step 4: Take the LED and insert it into holes F5 and F6 on breadboard. MAKE SURE THE LONG LEG OF THE LED GOES INTO F6.

Step 5: Take 1 jumper lead and attach it to E1 on the breadboard and pin 39 (GND) on the Pi.

Step 6: Take 1 jumper lead and attach it to E17 on the breadboard and pin 37 (GPIO 26) on the Pi.

Step 7: Take 1 jumper lead and attach to A1 on the breadboard. Now take the short length of bellwire, bend the end carefully around your finger then insert the other end into the free end of the jumper lead you just attached to the breadboard.

Step 8: Take the long piece of bell wire and bend it into an interesting shape. Remember – the more bends you add, the harder your game will be! Then insert the two ends of this piece of wire into A2 and A17 on the breadboard.

Step 9: Hook the loop you made in the short wire over one end of the bendy wire like this. Your Buzz Wire game is now complete! – Grab a tutor and ask them to check the connections now.

The program

Power up your Raspberry Pi. From the desktop menu, select Programming – Python 3 (IDLE). Then use File, New Window to create a new program.

Type in the following program, or alternatively you can use File, Open to open the buzzwire.py program in the Desktop/buzzwire folder.

Use File, Save to save this program as buzzwire.py in the Desktop/buzzwire folder and then run it with Run menu, Run Module.

from time import sleep
from os import system
from gpiozero import Button, LED

led = LED(4)
button = Button(26)

while True:
  if button.is_pressed:
    print("BUZZZZZZ")
    led.on()
    system("aplay buzzer.wav &")
    sleep(1)
    led.off()

What does the program do?

from time import sleep
from os import system
from gpiozero import Button, LED

The first three lines tell the computer to learn about new things. Computers can learn from programs that other people have written; we call these other programs "libraries". Our instructions tell the computer to learn how to run other programs (such as the sound player) from the system library, and how electrical buttons work (two wires touching) from the GPIO Zero library.

We then create a Button object and an LED object. We say the button is connected to pin 37 (GPIO 26) and the LED to pin 7 (GPIO 4).

led = LED(4)
button = Button(26)

This next line tells the program to run forever in a loop.

while True:

Next, the program runs until the wires touch. It then prints a message and plays the sound file.

  if button.is_pressed:
    print ("BUZZZZ")
    system("aplay buzzer.wav &")

Finally, the program waits for one second, then turns off the LED so play can continue.

    sleep(1)
    led.off()

Files

Buzzwire-gpiozero.pdf

The original PDF for this tutorial is available on Wikicommons: Buzzwire-gpiozero.pdf

buzzwire.py

from time import sleep
from os import system
from gpiozero import Button, LED

led = LED(4)
button = Button(26)

while True:
    if button.is_pressed:
        print("BUZZZZZZ")
        led.on()
        system("aplay buzzer.wav &")
        sleep(1)
        led.off()