1.1 Wand

Today we will use LED, Raspberry Pi and Scratch to make a fun game. When we wave the magic wand, the LED will blink.

../_images/1.1_header.png

Required Components

In this project, we need the following components.

../_images/1.1_list.png

It’s definitely convenient to buy a whole kit, here’s the link:

Name

ITEMS IN THIS KIT

LINK

Raphael Kit

337

Raphael Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION

PURCHASE LINK

GPIO Extension Board

BUY

Breadboard

BUY

Jumper Wires

BUY

Resistor

BUY

LED

BUY

Build the Circuit

../_images/1.1_image49.png

Add GPIO Extension

Click on the Add Extension button in the bottom left corner，then add the Raspberry Pi GPIO, an extension we use for all of our Scratch projects.

../_images/1.1_scratchled1.png ../_images/1.1_scratchled2.png ../_images/1.1_scratchled3.png

Load the Code and See What Happens

Load the code file from your computer(~/raphael-kit/scratch/code) to Scratch 3.

../_images/1.1_scratch_step1.png ../_images/1.1_scratch_step2.png

After clicking the magic wand in the stage area, you will see the LED will blink for two seconds.

../_images/1.1_step3.png

Tips on Sprite

Click on the Upload Sprite.

../_images/1.1_upload_sprite.png

Upload Wand.png from the ~/raphael-kit/scratch/picture path to Scratch 3.

../_images/1.1_upload.png

Finally, delete the Sprite1.

../_images/1.1_delete.png

Tips on Codes

../_images/1.1_LED1.png

This is an event block whose trigger condition is to click on the green flag on the stage. A trigger event is required at the beginning of all codes, and you can select other trigger events in the Events category of the block palette.

../_images/1.1_events.png

For example, we can now change the trigger event to a click on the sprite.

../_images/1.1_LED2.png

This is a block with a set number of cycles. When we fill in the number 10, the events in the block will be executed 10 times.

../_images/1.1_LED4.png

This block is used to pause the program for a period of time in seconds.

../_images/1.1_LED3.png

Since the BCM naming method is used in Scratch, this code is setting GPIO17(BCM17) as 0V (low level). Since the cathode of LED is connected to GPIO17, thus the LED will light up. On the contrary, if you set GPIO(BCM17) as high, the LED will turn off.