Scratch on a Raspberry

About

This project is part of my Masterthesis: «Learning Networks with new technologies like LoRa and connect it with physical computing».

Scratch: Running Scratch on a Raspberry Pi, add new extensions to establish a connection with a running server to connect Scratch with Python.

Scratch

This own scratch build is based on scratch-vm and scratch-gui. Both repositories were forked and supplemented with an own extension based on Scratch Extensions.

Requirements

• Raspberry Pi 4 (or 3) with the 64 bit Debian buster
• chromium as browser for running scratch
• Prepare Raspberry with the basics:
  • SSH-Access (passwordless if needed)
  • Remote Desktop Access

Installation

Node & NPM

$ curl -sL https://deb.nodesource.com/setup_14.x | sudo -E bash -
$ sudo apt install nodejs

# make sure, npm runs without sudo.
$ mkdir ~/.npm-global
$ npm config set prefix '~/.npm-global'
$ export PATH=~/.npm-global/bin:$PATH
$ source ~/.profile
$ node --version
$ npm --version
$ npm install -g npm
$ npm install -g webpack-dev-server
$ npm install -g webpack-cli

To install packages without sudo, checkout this one here: https://docs.npmjs.com/resolving-eacces-permissions-errors-when-installing-packages-globally

Install submodules

$ git submodule foreach --recursive git clean -xfd
$ git submodule foreach --recursive git reset --hard
$ git submodule update --init --recursive --progress

or run the prepared script

$ ./update-submodules.sh

Running Scratch locally on a computer

First time: run the following script once to get all necessary packages.

$ ./start-initial.sh

After that: run just the start-script to start the scratch-environment. Scratch is watching for changes in the code and reloads after changes.

$ ./start.sh

Scratch

You can test your own scratch project now on localhost:8601/

Running Scratch on a Raspberry Pi

This scratch-version is built to run with a python-server in the background to communicate with GPIO and LoRaWAN.

Please get first the scratch-server and install it to your raspberry on the same level as this repository.

.
├── home
│   ├── pi
│   │   ├── scratch-raspberry           # this repository
│   │   ├── raspberry-scratch-server    # the server repository
│   │   ├── Desktop                     # the final application will be copied to the desktop
│   │   └── ... 
│   └── ... 
└── ... 

Preparation on the Raspberry Pi

$ ./prepare-on-raspi.sh

Change the following settings: open the file manager (folder in the main menu)

Edit > Preferences > General

️[✔] Don't ask options on launch executable file

Virtual Keyboard

Install in chromium the extension "virtual keyboard" directly in the user-data-dir "/home/pi/log". To do this, start chromium with:

$ /usr/bin/chromium --user-data-dir=/home/pi/chromium-data https://facebook.com

With the first command, install the chromium-extension via the menu.

Manage Extensions → Open Chrome Web Store → Virtual Keyboard

Change the settings, that the virtual keyboard extension has access to file URLs:

Manage Extensions → Virtual Keyboard → Allow access to file URLs

In the extension-options of this extension you can change the keyboard layout if you want.

Now you can check if the keyboard is working:

$ /usr/bin/chromium --kiosk --user-data-dir=/home/pi/chromium-data https://facebook.com

Autostart

Add the Scratch-Application to the autostart:

$ sudo nano /etc/xdg/lxsession/LXDE-pi/autostart

Now add the following line before the screensaver line:

@sudo sh /home/pi/scratch-raspberry/system/launcher.sh

Running

After the preparation, there should be an app on the desktop to run. Just double-click it.

Otherwise you can start it by running on the raspberry pi (from the display, not via SSH):

$ ./run-on-raspi.sh