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To make sure your start in the Open Roberta Lab with the LEGO Mindstorms EV3 robot goes smoothly, you should read the following article thoroughly. We have tried to describe the preparation in as simple a way as possible. If you have any problems, please have a look at our FAQ first. If your question is not described there, you can simply send us an e-mail to

Components for Open Roberta®:

  • A computer running Windows or MacOS with an Internet connection.
  • A LEGO Mindstorms EV3 with the original firmware. (So simply a normal EV3)

1. Checking Firmware Version

For the transfer of programs to work, the latest LEGO Mindstorms firmware must be installed on the EV3.

You can find out which version is installed on your EV3 by following these simple steps:

  1. Go to Settings on your EV3.
  2. There you have to go to the bottom of the entries and select »Brick Info«.
  3. Under the menu point »Brick FW« the version of the firmware is displayed on the EV3.

    1. In order for your EV3 to work with the Open Roberta Lab you must have at least version V1.10E installed

      So if you see this display go to Step 3.
    2. Otherwise you have to update the firmware first.

      Don't worry, it's not difficult, just go to Step 2.

2. Updating your Firmware

If your EV3 does not yet have firmware version V1.10E, you will need to update it before you can program it using C4EV3. To do this, simply follow the instructions below:

  1. First you need to go to the following page:
  2. Scroll down the page to the button »Download Firmware«.

  3. Click on the button and save the firmware version on a data carrier (hard disk, USB stick etc.).

  4. Now go to the Windows Explorer and open the folder of the LME Ev3 software where the firmware is stored. The path to this folder may look like this:
    C:\Program Files (x86)\LEGO Software\LEGO MINDSTORMS Edu EV3\Resources\Firmware\Education

  5. Now you can move the firmware you just downloaded to this folder. The new firmware is called »LME-EV3_Firmware_1.10E.bin».

  6. Then open the LME EV3 software and click Update Firmware in the Tools menu.

  7. A drop-down list will appear and you can select the new firmware version V1.10E.

  8. Finally, connect your EV3 brick to your computer via USB, turn on the brick and confirm the software update in the dialogue box.

3. Transferring a Program to your EV3

Once you have finished your first program and want to see the result, you need to transfer your program to the EV3. To do this, follow these steps, depending on your Operating System:

Windows 7, 8, 10 and MacOS

  1. First press the »start on EV3« button in the Open Roberta Lab. 
  2. Then right-click on the program name. This always ends with ».uf2«.
  3. Press »Save target as ...« and save your program directly to your EV3. You can find it under the name »EV3«
  4. The EV3 emits a sound twice in quick succession as soon as the program is finished.

    1. You can now select your program in the Program tab and start it. First select the name of the program. If you haven't given it a name yet, it is »NEPOprog«.

      If your program is not yet displayed, switch briefly to another tab and then return to the program tab. Now your program should be displayed.

    2. A submenu opens where you can start the program.


Under Linux you can't simply transfer the files created by the »Open Roberta Lab« to your EV3. In order to be able to transfer the programs, you must first install a small script from us. How to do this and how to use the script afterwards is explained in the next section.


  1. Download this folder and remember where you saved it.

  2. Navigate to the directory where you saved the folder and unzip it. You should remember the target directory where you unpack the folder, you can also delete the ».zip« file now.

  3. Open the console (for Ubuntu CTRL+ALT+T) and navigate to the directory where you unzipped the folder. The folder inside is called »upload-c4ev3«. If you are in it, you can continue with the next step.

  4. Install the script with it:

  5. If no error message has been produced, the script is installed and you can transfer your programs to your EV3.


  1. Create a program in the »Open Roberta Lab«, download it and save it in a folder you know (e.g. downloads).

  2. Connect your EV3 to your computer via USB.

  3. Open the console and navigate to the folder where you downloaded the program.

  4. Start the script. This will transfer the program to your connected EV3. You start the script with :

    upload-c4ev4 NEPOprog.uf2

    where »NEPOprog.uf2« is the name of your program, so it can also be another one. If so, you must enter the new name of your program here as well.

  5. if no error messages were produced during transfer your program was successfully transferred to your EV3. You can continue with Step 4 in die Windows section.


If you no longer need the script, you can easily uninstall it by following the steps below:

  1. If you have already deleted the folder you unzipped during installation, you will need to download it again, as you will need a file from it. This is not the folder mentioned above, but the folder where you unpacked the file. To get back to the data, simply follow the first two steps under "Installation".
  2. Open the console and navigate to the folder "upload-c4ev3" of the installation.
  3. Start the uninstall script with :

  4. The script was successfully uninstalled, if you want to use it again, you have to install it again.

4. Important information during use

Unfortunately the EV3 cannot handle special characters in the file name of the ».uf2« files. The Open Roberta Lab always creates files with real names, but your Operating System appends » (1)«, » (2)« or » (3)« to files with the same name. However, this only happens if you save the programs on the computer first and move them yourself on the EV3. If that happens, just rename the file before you move it to the EV3. If you save your programs directly to the EV3, the problem won't happen at all.

The following characters are allowed in the filename:

  • Alphanumeric values (A to Z, a to z and 0 to 9)
  • Hyphen ( - ) and underscore ( _ )

So spaces and special characters like ä,ü or ß are not allowed int the file name.

Good filename example: NEPOprog.uf2, NEPO_program_square.uf2, EV3quadrat5.uf2

Examples of bad file names: NEPO.Prog.uf2, NEPO:EV3:Square.uf2, EV3square (1).uf2, EV3 square.uf2

The message blocks will only work if you have previously paired the robots via Bluetooth using the EV3 menu. To pair two robots, follow these steps:

Give your robots a unique name using the EV3 Settings menu → »Brick Name« before pairing them via Bluetooth. This makes it easier for you to find the right robot to pair.

  1. Take the following steps first on both robots:
    1. Go to the settings menu on your EV3 and select the third item »Bluetooth«.
    2. Now activate the two points »Visibility«  and »Bluetooth« and save your changes by clicking on the check mark at the bottom.

      Power consumption

      As long as Bluetooth is active, your EV3 consumes a little more battery. So it's best to turn it off when you're done programming with messages.

  2. Now go on one of the two robots back to the Bluetooth menu and there to the top point »Connections« to select a robot to connect.
  3. If you now see the right robot in the list select it from the list they are now paired.
    If you have never connected to the other robot before, search for robots first. Select the entry »Search«. This will take a while.

  4. Once the available robots are displayed, select the correct one from the list of available robots.
  5. Now you have to confirm on both robots that they are allowed to couple.
  6. As a safety test, you must now enter a code on both robots. Which one is not important, as long as it is the same on both robots. The robots are paired, after both have confirmed the code.

5. Using Text-to-Speech

If you want to use a version of the block »say« in your program, the EV3 needs some data. However, this is very easy to do. Just download this folder, unzip it and save it to an SD card. This SD card has to be inserted into the SD card slot of your EV3 before starting the program.

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