Snap4Arduino (original) (raw)

Arduino goes lambda!

Snap4Arduino 10.3.6 released on January 8, 2025

Download desktop versions or play it online
Online needs a Chromium/Chrome/Edge browser with the Snap4Arduino Connector extension (download it or install it directly on your Chromebook)

Snap4Arduino

Snap4Arduino is a Snap_!_ extension. A full Snap_!_ implementation that can interact with the physical world, through many types of electronic devices, especially those compatible with Arduino.

Snap_!_

Snap_!_ is a broadly inviting programming language for kids and adults that's also a platform for serious study of computer science. It is inspired by Scratch, written by Jens Mönig and Brian Harvey and presented by the University of California at Berkeley.

Features

Installation

Snap4Arduino requiere boards with Firmata firmware installed. Check devices section.

Snap4Arduino online

Chromium/Chrome/Edge browsers are required

Download Snap4Arduino connector, unzip its crx folder, type chrome://extensions, select Developer mode and Upload an unpacked extension selecting that crx file (or just drag and drop it).

Just play Snap4Arduino online (you can install it as an app from the browser to run it offline).

Downloads

The project and all its components (including Snap_!_) are registered under public free software licenses (AGPLv3 and MIT), so you can download the sources and pretty much do whatever you want with them!

Desktop version

Supported Devices

Snap4Arduino requires boards with Firmata firmware uploaded.

UNO boards

You can upload Firmata firmwares direcly from Snap4Arduino (with both desktop and online versions) to UNOs compatible boards. Or just here:

### Demos

Here's a couple of fun things that can be done with Snap4Arduino, most of them recorded on a Hi-Tech last generation potato camera.

###### A line follower with parking lights

###### An ultrasound ruler

###### An LCD screen

###### An Etch-A-Sketch that streams itself to any device over the network (source)

###### A shy Poppy Ergo Jr Robot

###### Music for a horror film of the 50s (source)

###### A machine that beats you at Tic-Tac-Toe

###### A mechatronic teddy bear

###### A Phiro robot

###### Two laptops communicating via Morse

### Source Code

You can find our GitHub repo at Snap4Arduino@GitHub. Please feel free to send us your pull requests and participate in reporting, fixing or commenting on bugs!

### HTTP Protocol

http://IP:42001/

Snap4Arduino comes with a built-in tiny HTTP server that mimics (and extends) the one Scratch 1.4 had. This means you can control your Snap4Arduino application from any computer, mobile phone, tablet or any other network-enabled device in the same network. In the following sections, the word IP refers to the IP address of the machine that has Snap4Arduino running on it.

###### Giving orders to Snap4Arduino

/broadcast=MESSAGE

Point your browser to http://IP:42001/broadcast=MESSAGE

This will broadcast the message MESSAGE to Snap4Arduino, where you can capture it with a regular When I receive [MESSAGE] block.

These public messages must begin with the + character. The rest of the messages are treated as private and thus are not accessible from the network.

###### Updating the value of a Snap4Arduino variable

/vars-update=VARIABLE-NAME=VARIABLE-VALUE

Point your browser to http://IP:42001/vars-update=VARIABLE-NAME=VARIABLE-VALUE

This will set the global variable called VARIABLE-NAME to the value VARIABLE-VALUE.

This only works for global variables that start with the + character. Any other variables are not editable. Bear in mind that variables with names containing the '=' character can not be used, even though Snap_!_ supports them.

You can also update multiple variables at once by means of a POST request (see below).

###### Finding out which messages is Snap4Arduino listening for

Point your browser to http://IP:42001/send-messages

This will show a list of all message names for which Snap4Arduino has When I receive [message] hat blocks, as long as the message starts with the + character (other messages are private).

###### Getting variables and their values from Snap4Arduino

Point your browser to http://IP:42001/send-vars

This will show a list of all global variables defined in Snap4Arduino whose name starts with the + or with the - character (variables starting with + are editable, while variables starting with - are only readable), along with their current value.

###### Getting the value of a single variables from Snap4Arduino

/send-var=VARIABLE-NAME

Point your browser to http://IP:42001/send-var=VARIABLE-NAME

This will return the value of the variable ready for you to use, no string manipulation needed. The variable must start with the + or - character to be accessible from the network.

###### Getting a real-time stream of the stage in Snap4Arduino

/stage

Point your browser to http://IP:42001/stage

This will render a real time version of what's going on in the stage, like shown in this video.

You will be presented with an auto-refreshing HTML page, enabling you to watch the stage contents in your browser, though in a non-interactive way. You need to enable Public Stage from the settings menu for this to work. Otherwise, the stage is not accessible from the network.

###### Getting a snapshot of the stage in Snap4Arduino

/stageimg

Point your browser to http://IP:42001/stageimg

This will render a snapshot of the Snap4Arduino stage in the form of an image encoded in base64 that you can use for any purpose. You need to enable Public Stage from the settings menu for this to work. Otherwise, the stage is not accessible from the network.

###### POST. Updating multiple variables of Snap4Arduino from an HTML form

You can update multiple global variables in your project at the same time by means of an HTML form sent through a POST request.

By using and

Note that Snap4Arduino expects all queries to be UTF-8 encoded. To make sure your query goes through properly, especially when dealing with special characters, you can always use: