Starter Guide ScratchLink


ScratchLink is an integrated educational coding and robotics system for Primary and Up, based on Scratch3 & incorporating Blockly which interprets user code to Python and JavaScript.  ScratchLink is a platform neutral browser based block coding system so use with PC, Mac, Ipad, Iphone and Android which also integrates Arduino, EV3, WEDO with ScratchLink hardware and inexpensive generic sensors & peripherals.  The ScratchLink system allows the user to directly execute code from their browser via wifi, Bluetooth & USB serial.  Companion curriculum modules and tutorials.  Develop IOS and Android phone apps to interact with ScratchLinks.

ScratchLink is a family of hardware that allows Scratch to directly interface with robotics and microcontrollers and various sensors and hardware i.e. Arduino and EV3 Lego etc. ScratchLink works with browser based Scratch3 so Ipads, Macs, Linux and Windows systems will all use the same browser plugins.  ScratchLink has an Arduino compatible microcontroller that connects to your computer with the USB cable and sometimes you may need to manually update the USB driver if Windows does not auto detect.  You also need to run the ScratchLink Helper App while interfacing between Scratch and ScratchLink which also authenticates the ScratchLink as genuine.

ScratchLink USB Setup:

Check USB Port: When you plug in ScratchLink with the USB cable windows should auto detect the serial USB chip.  ScratchLink could have either the CH340 or Silicon Labs USB chip.  To check this in Windows go to your “Control Panel” then “Device Manager” the “Com Ports”- You should see one of the COM ports showing either “USB-SERIAL CH340(COM#)”  or “Silicon Labs CP210x USB to UART Bridge(COM#)”.  If you see this then note the COM port number- if there are lots of COM ports showing and you don’t know then watch the list and remove ScratchLink from the USB port and not the entry that disappears- this is ScratchLink.

Install USB driver if needed:  If you got “Serial Device?” or similar in the first step then Windows does not have the USB driver.  So we need to “update” the driver.  Download and unzip the CH340 USB Driver then “right mouse click” the entry in COM ports (Device Manager) with the “Serial?” or “Unknown Serial Device” – upon “right click mouse” select “update driver” then navigate the folder of the unzipped CH340 USB Driver.  ScratchLink should now appear as “USB-Serial CH340(COM#)”, if not then it could need the Silicon Labs driver, in which case download and unzip the Silicon Labs USB Driver and run the executable install file for either 32 or 64 bit machine.

ScratchLink Helper App

Start ScratchLink Helper App:  Download, unzip and copy the ScratchLink Helper App to your preferred folder and make a shortcut to the desktop if desired.  Start ScratchLink Helper App and “allow” it to get past the windows firewall if you get warnings.  Plugin ScratchLink hardware such as WiInterface and it should populate the COM port dialogue box at the top of helper app.  Press “connect hardware” and then “test LEDs” whereupon the LEDs on the WiInterface should do a quick multicoloured demonstration.  The “Hardware” box should show “USB connected” and be green.  If no COM port displays at the top then you need to install the USB driver as above or you didn’t plug in the USB cable or maybe try another COM port or rebooting.  When you start Scratch the “Scratch” dialogue will show green and “connected” in the helper app.  You must have the helper app going to use ScratchLink.

Install Scratch2 Offline:  Install Scratch 2 Offline Editor on local computers or use a network MSI for Scratch2.  You will need Adobe Air and make sure that your Adobe Flash is up to date before installing the latest Scratch2.

Import your ScratchLink blocks into Scratch2 Offline by holding down “Shift” then click “File” and “Import experimental HTTP extension” and navigate the ScratchLink Blocks that you which to import.  Note that imported blocks can’t stay inside Scratch itself but if you simply save an empty project file after importing the blocks and start Scratch using this empty project then the imported blocks will be available.  This is because imported blocks are stored with the project itself i.e. “Scratch2 project file” not inside the Scratch2 program itself.  

Download and unzip desired blocks below.  The imported ScratchLink blocks will show under the “More Blocks” tab in Scratch2 and if you have a ScratchLink plugged in and the helper app going then the dot in “More Blocks” will be green not red, indicating a live serial connection from Scratch2 to ScratchLink.  You can can now start interfacing with ScratchLink directly from Scratch with Scratch coding.

Windows Bluetooth: Connect Code Editor to ScratchLink Hardware


ScratchLink hardware automatically broadcasts its Bluetooth name, however, windows needs to be paired with that device first and you need to determine the SPP COM port.  If you have a desktop without inbuilt Bluetooth then you will need to setup a Bluetooth dongle first.  While windows handles the Bluetooth connection from ScratchLink hardware, our ScratchLink Helper App needs to run in the background to link our browser coding platform to windows Bluetooth.  Both are explained below.

Step 1: Setup Windows Bluetooth Pairing & Determine SPP Com Port

This needs updating with new BT APP

ScratchLink hardware (i.e. eBots etc) automatically broadcast their Bluetooth name for pairing.  If your PC doesn’t have Bluetooth then setup the Bluetooth dongle first.

How to pair and determine SPP COM port:

  1. Turn on ScratchLink
  2. Go to Windows Bluetooth icon and right click “add Bluetooth device” then add Bluetooth device and select the ScratchLink and windows will automatically pair and setup the COM port
  3. Go to Windows Bluetooth icon and right click “Open Settings” then “COM ports” and note the COM port number with the “SPP” at the end- this is your COM port for the ScratchLink on this computer
  4. You can now start ScratchLink Helper App and select the COM port from the step above and you will now have a Bluetooth serial connection between Windows and ScratchLink.

Step 2: Launch ScratchLink Helper App & Connect to Bluetooth COM Port

While windows handles the Bluetooth connection from ScratchLink hardware, our ScratchLink Helper App needs to run in the background to link our browser coding platform to windows Bluetooth.


Download the latest ScratchLink Helper App (unzip after downloading)

Launch our ScratchLink Helper App (that you downloaded above and then unzipped)- Windows will say that it is an unverified publisher (only first time though) and you need to click “more info” and “run anyway” – please be patient as this can take a few minutes on the first run- eventually Windows will ask for firewall approval and click yes and then our Helper App will run.

Turn on ScratchLink Hardware i.e. eBot etc and in ScratchLink Helper App, select the SPP COM Port from step 1 and click the “connect box” and then you should see a green “connected” box and data coming up in the window.

You can now go to and it should automatically connect to our Helper app which in turn is connected to Windows Bluetooth which is connected to ScratchLink hardware.

eBot Hardware

ScratchLink has a range of mobile robots and all are called “eBots” such as Junior, Max and Mini.

Check Inputs & Outputs with Scratch

The following video describes how to check basic functioning of all sensors and outputs using Scratch Editor.

Check Inputs & Outputs @ Command Line with Serial Terminal

ScratchLink works by sending and receiving serial data to the ScratchLink microcontroller either by serial USB, Bluetooth or Wifi.  This can be achieved either with Scratch Code Editor, Serial Terminal (eg Putty), Python and JavaScipt etc. 

This section explains how to send and receive data via a serial terminal such as Putty.

Download and install your favorite serial terminal like Putty (64-bit PC version).

Putty setup:

  1. Connect ScratchLink to PC via USB serial or Bluetooth as desired and ascertain correct COM port number.
  2. Set the Connection Type to “Serial” and choose appropriate COM port with Speed of 115200
  3. On LHS Category- select “Terminal” and set Local Echo and Local line editing to “Force on” (this allows you to see what you type)
  4. Go back to Category “Session” and Save your settings as “ScratchLink” or whatever you desire.
  5. Click on the “Open” button and your terminal window will open and you will see the info from the ScratchLink – if you don’t then you have done something wrong

Once you have established serial connection and have your Putty terminal window open then consult the Command Reference Manual or try these basic commands to test inputs/outputs:

  • wheels drive;
  • wheels off;
  • led demo;
  • matrix random;
  • matrix off;
  • stream on;

Now you will see all the data packets streaming back in the terminal window- check the ultrasonics and color sensors by moving the eBot around and watching for values changing.  Watch the video below for further help.

eBot Junior Hardware Info

Hardware Overview:

eBot Junior uses the eBot Max Combo board with the following hardware features:

  • 2 x NEMA 17 stepper motors
  • 2 x color/light sensors
  • 2 x ultrasonic range sensors
  • 16×16 Dot Matrix display
  • 2 x LED 8bit rings

The battery pack has 4 x 18650 lithium ion cells with on-board charging circuit which automatically disconnects power to robot when the charging USB is connected.  Charging via USB phone charger or computer USB port (don’t use laptops).

Battery Instructions:

Upon initial use the 18650 lithium ion batteries will need to be placed in the battery holder under the eBot and charged over night by computer USB port or phone charger (i.e. 5V DC via USB at rear).

Flat end of 18650 lithium battery is negative and goes toward the spring or negative end of the battery holder (see photo below).  Reversing the polarity of the batteries in the holder may cause fire or explosion.  Battery handling must always be supervised and conducted according to your health and safety and risk management protocols.

Please only use new or similar sets of 18650 batteries and avoid mixing used batteries as this may cause charging imbalances.

Warning:  if batteries become hot then immediately place in a safe fire proof area till cool and safely dispose.  Never short circuit lithium batteries as this may cause fire or explosion.

Dot Matrix Editor

The 16×16 Dot Matrix display allows pixel graphics to be displayed.  These dot matrix graphics can be created inside ScratchLink Code Editor or in a separate Windows program called Dot Matrix Editor.


Download Dot Matrix Editor for Windows (unzip after downloading)

 Instructions for using the Dot Matrix Editor for Windows and creating Scratch code using the stored images is explained in the following video.