Snow globe

Step 1: Make it

What is it?

Make it snow on your micro:bit by shaking it, and press button A to hear a 'twinkle'.

What you'll learn

You will learn how to create an animation on the micro:bit’s LED display, how to use the micro:bit’s accelerometer to react to movement, and to play expressive sounds on your micro:bit. You will also find out how to use loops in a computer program.

How it works

• This program uses the micro:bit’s accelerometer input to sense when it’s shaken.
• When the accelerometer senses sudden movement, the program shows an animation of moving snow on the micro:bit’s LED display.
• An image of a chequerboard pattern and its inverse are shown in a sequence to create the illusion of movement.
• After showing each image, the program pauses for half a second (500 milliseconds) before showing the next image. This slows the animation down.
• The program uses a count-controlled loop to show the sequence of images ten times. Loops are also known as iteration.
• The snow globe uses the button A input to play the expressive sound ‘twinkle’.
• You will need a micro:bit V2 to play expressive sounds. If you have a micro:bit V1, you could just use the animation code. Or you could attach headphones and play music using the ‘play melody’ block instead. Using crocodile clip leads, connect micro:bit pin 0 to the tip of your headphone plug, and GND to the longer part of the headphone plug.

What you need

• a micro:bit
• MakeCode editor
• battery pack (optional)

Step 2: Code it

1# Imports go at the top
2from microbit import *
3
4
5while True:
6    if button_a.was_pressed():
7        audio.play(Sound.TWINKLE) 
8    if accelerometer.was_gesture('shake'):
9        for i in range(10): 
10            display.show(Image('90909:'
11                               '09090:'
12                               '90909:'
13                               '09090:'
14                               '90909'))
15            sleep(500)
16            display.show(Image('09090:'
17                               '90909:'
18                               '09090:'
19                               '90909:'
20                               '09090'))
21            sleep(500)
22        display.clear()
23

Step 3: Improve it

• Use other inputs such as pressing button B to play festive tunes using the ‘play melody’ block. See the Frère Jacques loops project for how to do this.
• Make a more realistic animation of falling snow using several ‘show LED’ blocks.
• Adapt the Nightlight project to show moving snow on the LED display if it gets dark.