With the Raspberry Pi 4, you can now program in the latest version of Scratch, a popular programming language for beginners. Additionally you can use the new Scratch Raspberry Pi extensions to interact with Scratch in a more physical way.

This guide will go through how to set up the Raspberry Pi 4 to program with Scratch 3. Additionally, we will run through a demo showcasing some of the possibilities that this dynamic combo of a powerful microprocessor and intuitive, easy to learn programming language allows.

What's Scratch?

Scratch is a block-based language geared for beginners that lets you create your own interactive stories, animations, games, music, and art.

Scratch is easy to use and requires no prior coding experience!

Parts

Here's what you'll need to get started

1) Raspberry Pi 4 with your choice of RAM (any will do just fine!)

2) Pi power supply

USB C power supply 

or you can use USB micro B power supply with an an adapter

3) Display

You can use any display with an HDMI input.

We also have some options:

4) Micro HDMI to HDMI Cable

5) Keyboard and mouse

6) 16GB Micro SD card w/ Noobs

7) 1K ohm resistors

8) Female to male jumper wires

9) Breadboard

10) Leds

We will be using the official Raspberry Pi guide to set up the Pi 4. Head over there for instructions on how to get your Pi up and running.

Set up the SD card

The SD card linked in the "parts" section of the "overview" page has NOOBS pre-installed on it so if you have an SD card with NOOBS installed already, skip ahead to the "Connect your Pi" section. However if you have another SD card and want to install NOOBS follow the steps in the "Set up the SD card" section.

Connect your Pi

• Insert the SD card into the slot on the Pi
• Connect keyboard and mouse via the Pi's USB hubs
• Power up display then connect to Pi via micro-hdmi cable
• Add any other optional connections

Start up your Pi

• Power up the Pi via usb c cable
• Download Raspbian via NOOBS

Finish the Setup

• Configure country, language and timezone
• Set up password for Pi
• Connect Pi to wifi network
• Install any necessary updates

Update the OS to Raspbian Buster

Follow the instructions via video or text below to update your Pi

First, open a terminal window

In a terminal window type and return:

sudo apt-get update

Next type and return:

sudo apt-get dist-upgrade

When prompted, y/n type y and return.

This will update your Pi's operating system to Rasbpian Buster which may take some time. (10 - 15min)

When the update is complete, restart the Pi by running the command:

reboot

Trouble Shooting 

Problem: My screen is not showing any output from the Raspberry Pi.

Potential Solution 1: Make sure all connections are in place before booting up Pi. 

Potential Solution 2: Double check that your SD card has NOOBS correctly installed.

Now that we're all set up, it's time to get Scratch up and runnin'!

What can I do with Scratch?

As mentioned earlier, Scratch is a block-based language geared for beginners that lets you create your own interactive stories, animations, games, music, and art.

For more on the ins and outs of Scratch check out the guide: 

Scratch 3 Walkthrough and Demo

Connecting to the world

While you do not need a Raspberry Pi to run and use Scratch (there is a web-based editor that can be used on any computer with a browser), the Pi unlocks a whole other set of capabilities for us. 

Connecting this powerful programming language to a Raspberry Pi lets us more easily take advantage of the "GPIO" pins to have our Scratch program interact with the outer world!

How to install Scratch 3 using the Recommended Software app

Open up the menu, click on Preferences > Recommended Software, and then select Scratch 3 and click on OK.

How to install Scratch 3 using the terminal

Open a terminal window, and type in and run the following commands:

sudo apt-get update
sudo apt-get install scratch3

Add the Extension

Once Scratch 3 is installed on the Pi, go ahead and open up Scratch 3 by clicking the Raspberry Pi icon on the top left of the desktop, then Programming>Scratch3

Add the Raspberry Pi GPIO extension

Now we have access to some awesome GPIO functionality which we'll get to next!

Read more about the different Raspberry Pi extensions for Scratch here!

Which version of Scratch to use?

While you can use any version of Scratch, if you have a Raspberry Pi 4, we recommend using Scratch 3. Follow the instructions on the next page to get Scratch 3 on your Pi 4.

If you have an older Pi however such as a Pi 3 or older, you may not be able to run Scratch 3 because of the memory requirements of the program.

You can however run Scratch 2 which still has Raspberry Pi GPIO functionality, so skip to the section "Scratch 2" to find out how.

How to open Scratch 2 on the Pi

Once you are in the Raspbian desktop, you will open up Scratch 2 which comes preinstalled on the Pi.

To Open Scratch 2:

Click the Raspberry Pi icon on the top left of the desktop, then Programming>Scratch2

And that's it! Scratch is ready to go!

Adding the Pi Plugin

Open the More Blocks panel, click Add an Extension, and select Pi GPIO. You should then see two new blocks appear:

You can use these two purple blocks to control output pins or read input pins by entering the pin number into the field, or using a variable containing the pin number.

Next up, putting the spiffy new blocks to work.

Blinky LED demo

We will now put together a small demo using the Pi and some components. In this simple demo we will use Scratch to program the Pi to blink an LED.

Wiring

First, let's wire things up.

You will need handy:

• one led (any color)
• one resistor that is 1K or less (click here for more on how to determine resistor values)
• 2 female to male jumper wires

Next we'll program the Pi in scratch to blink the LED.

Going Further

What else can you think of to use with Scratch and Raspberry Pi?

Some ideas:

• Add buttons and other components.
• Create a custom interactive game by connecting buttons, leds and other components. Then program these components to control and react to game elements like sprites and backdrops.
• Add a CRICKIT HAT to make things move!

Next we'll program the Pi in Scratch to blink the LED.

Now click the green flag and see what happens!

Use Scratch 2 to program the Pi to blink the LED.

Now click the green flag and see what happens!

Going Further

What else can you think of to use with Scratch and Raspberry Pi?

Some ideas:

• Add buttons and other components.
• Add a CRICKIT HAT to make things move!
• Use the Sense HAT extension to sense tilting, shaking, orientation, use a joy stick, measure temperature, pressure humidity, display text and more.
• Create a custom interactive game by connecting buttons, leds and other components. Then program these components to control and react to game elements like sprites and backdrops.

Click below for some more resources and ideas of what else you can do with Raspberry Pi and Scratch!