Make: Projects

Universal Translator

Translate between thousands of language pairs using the Raspberry Pi.

If you’ve ever tried to communicate with someone who only spoke a foreign language, you know that it can be extremely difficult — even with the help of modern translation websites. This project will show you how to turn a $35 mini-computer into a feature-rich language translator that not only supports voice recognition and native speaker playback, but is also capable of translating between thousands of language pairs. The unbelievable part is that it can all be done on the cheap by leveraging inexpensive hardware, free translation APIs, and some open source software.

Even if you’re not interested in building this exact translation tool, there are still many parts of this project that might be interesting to you such as Google’s speech recognition API, Microsoft’s translation API, and text to speech. All of the source code for this project is publicly available on Github, and you’re welcome to use and modify it as you wish. The Universal Translator makes a perfect weekend project because it incorporates a wide range of technology and tools to create something immediately useful. Oh, and it’s a blast to play with.

Pick up all the parts at your local RadioShack, follow the instructions below, and you’ll have your own babel fish in no time.



Step #1: Set up Raspberry Pi and Download Software

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  • If you don't already have your Raspberry Pi up and running, follow the instructions provided by the Raspberry Pi Foundation:
  • Make sure your Raspberry Pi is connected to the internet. If you don't have an Ethernet connection handy, you can use a USB wi-fi dongle to connect to your network.
  • From the command line, run the following two commands to update the software on your Raspberry Pi: sudo apt-get update sudo apt-get upgrade This process may take a while.
  • Install the software required for this project with these commands: sudo apt-get install python-pip mplayer flac python2.7-dev libcurl4-gnutls-dev sudo pip install requests pycurl
  • Note: This project was tested with the latest version of Raspbian at the time of publishing. Be aware that some details may change as updated software is released. To check your version against the version in our test build, execute uname -a from the command line: [email protected] ~ $ uname -a Linux raspberrypi 3.12.22+ #691 PREEMPT Wed Jun 18 18:29:58 BST 2014 armv6l GNU/Linux

Step #2: Configure and Test Headset

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  • Plug in the USB headset (use a powered USB hub, if necessary).
  • Run the following commands, which will list your sound devices: cat /proc/asound/cards cat /proc/asound/modules You should see that the Logitech Headset is listed as card 1. The second command should show that the driver for card 0 (the default output) is snd_bcm2835, which is the Raspberry Pi's analog audio output. The driver for card 1 (our Logitech Headset) is snd_usb_audio. If you don't see the headset listed, try rebooting: sudo reboot
  • In order to set the USB headset as the default for both audio input and output, you'll need to update the ALSA configuration file. Open it in the text editor nano: sudo nano /etc/modprobe.d/alsa-base.conf
  • Change the line that says: options snd-usb-audio index=-2 to: options snd-usb-audio index=0
  • Save and close the file with Ctrl-X and typing y. Reboot the Raspberry Pi using the following command: sudo reboot
  • After the reboot, the sound system should be reloaded so that when you run the above commands cat /proc/asound/cards cat /proc/asound/modules again, you should see the USB Headset is now the default input/output device (card 0) as shown above.
  • Test it out by recording a 5 second clip from the microphone: arecord -d 5 -r 48000 make.wav Note: If you see an error that says "overrun!!!", you can safely ignore it.
  • Play it back through the headphone speakers: aplay make.wav Don't worry if the audio is a bit scratchy, you will be recording at a higher quality in the next step.
  • To adjust the levels you can use the built-in utility alsamixer. This tool handles both audio input and output levels. sudo alsamixer

Step #3: Download and Extract Source Code

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  • There are a few options for speech recognition with Raspberry Pi, but I thought the best solution for this tutorial was to use Google’s Speech to Text service. This service allows you to upload the audio file that was recorded and convert it to text (which you will later use to translate).
  • The project source code will handle this process for you. To download and extract the files, run the following commands: wget unzip cd PiTranslate-master Note: There is a combination of shell and Python scripts in the bundle.
  • Make the speech to text script executable: sudo chmod +x

Step #4: Set up Google Speech Recognition API

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  • In order to use Google's speech recognition API, you must register for it. Follow these steps while logged into your Google account.
  • Go to and click "Create Project." Give it a name like "My Universal Translator" and click "Create." (Google will generate a random Project ID. You can leave this field alone.)
  • While Google's cloud servers create your new project, open a new browser tab to join the Chromium-dev Google Group, which will give you access to the Speech API:!forum/chromium-dev
  • Return to your Google Project tab. If the process of creating your project is complete, you'll see the Project Dashboard. Click "APIS & AUTH" on the left side and then click "APIs." Scroll down and turn on the Speech API.
  • Still in the Project Dashboard, click "Credentials" on the left side, under the "APIS & AUTH" header. Click the button "Create new Key" and select "Browser Key." Leave the allowed referrers text field blank and click "Create." The newly generated API key is now displayed in the dashboard.
  • On your Raspberry Pi, open the file and find the line that says: key = 'xxx' Replace xxx with the key from your dashboard. To make this easier, you may want to launch the Raspberry Pi's desktop environment (with startx), log into your Google account with the web browser Midori, and copy and paste the key into the file. You could also change the file via SFTP from your computer.
  • Note: While free, Google's speech API only allows 50 requests per day.

Step #5: Set up Microsoft Translation API

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  • Google has a translation API as well, but for this project, you'll use Microsoft's service because it's free. Log into Microsoft's Azure Marketplace with your Microsoft account at:
  • Click the button that says "REGISTER" to create a new application.
  • Fill in a Client ID, Application Name, and Redirect URI (any URL will do).
  • Click "CREATE"
  • Much like you did with the Google Key in the previous step, save the Client ID and Client Secret between the single quotes on the appropriate lines in args = { 'client_id': '',#your client id here 'client_secret': '',#your azure secret here 'scope': '', 'grant_type': 'client_credentials' }

Step #6: Use the Universal Translator

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  • Now that the API keys have been created and entered into the provided code, you can try out the Universal Translator. With the headset on, execute: ./
  • Speak into the headset and press Ctrl-C when done.
  • You'll hear the translation in the headset and you'll also see feedback on the command line.
  • By default, it translates from English to Spanish. You can easily change your origin and destination languages in the last line of and the script will do the rest! There are literally thousands of language pairs supported. Enjoy!
Dave Conroy

Dave Conroy

Boston Based Raspberry Pi nerd who eats, sleeps, and breathes all things tech. @conroydave

  • Peter Ruffini

    Dave, does it translate “stupid”? I have a hard time understanding that and haven’t been successful in finding a translation solution. :-) Seriously though, this is pretty cool!

    • Dave Conroy

      Peter, that is scheduled for version 2.0!

    • nomasteryoda

      Stupid like Vogon sir?
      Vogon poetry
      translated much wow!

      • MerleEMoore

        my neigbour just got a nice year old Mercedes-Benz just by some part-time working online with a cheap laptop. Learn More

  • MAC

    Well done sir.

  • Yuliyan Ilev

    Is there a way to make a physical button to execute the ./ ? I am planning to use this in an exhibition and it would be amazing if people yould just press a button istead of typing command lines. I am sure it is not hard to make but i have no idea how. The kind of button i´d like to use is a usb buzzer like that. Could you help me?

  • ShakeSpear

    Awesome tutorial. I followed it up and I got almost everything to work. I don’t have USB Microphone, I have the Apple Headphones (with Mic) and I also ave just mic. I couldn’t seem to be able to test my mic and at the end I got this error:

    I took a screenshot to ease the explaining pain.


      The RPi does not support mic input on the headphone jack. Sorry.

  • Amanda Odena

    A “stupid” translator? I’ll take one!

  • Ian Burgess

    What a fantastic project. I completed it in such a small amount of time, and yet the payoff is so huge. I am going to redo it with my young kids and get them introduced to the RasPi, APIs, and the framework of modular programming. Great stuff, Dave!

  • ppolstra

    A note on power. I did a lot of research on power requirements for small computer boards while writing Hacking and Penetration Testing with Low Power Devices (Syngress, 2014). The more energy efficient BeagleBone Black with a wireless adapter will only run about 7.5 hours off of AA batteries. The Pi is not nearly as efficient and will likely get your 4-5 hours off of the AA batteries on a good day. So if you want to make the translator portable be prepared to spend some cash on the batteries. Incidentally, moving up to C sells with better than triple the run time.

  • Guest

    my headphones won’t show up and I rebooted. Ideas?
    P.S. they work fine on my desktop

  • Alin

    I used a “translate Api” and it is translating the feed back too. It won’t here my speech so I think I need to use the speech Api but I could not find it? It wasn’t listed. Can you help me.

    • rafi

      you need to join the Chromium-dev Google Group the link is in the page

  • Alin

    I keep getting an error saying cannot find an active azure marketplace translator subscription associated with the requested credentials: ID=3627.V2_Json.Translate.556BCC47

  • Rajamani Vinayagam

    Dave, I have tried your code, am getting follwing error while trying to execute speech to text.. please advise on this..

    • marcus evans

      was there an answer to this? i’ve come across the same problem

      • Rajamani Vinayagam

        Copy & pasting Speech API key solved my problem..

      • C Johnson

        I’m having that same problem too.


    thank you so much sir for providing such useful information and project which we can use in our day to day life.
    our universal translator is running successfully ,but sometimes due to some ssl certificate issue it does not operate but after rebooting it operates succesfully.

  • Patricia Suarez Valero

    Hi!!! I’ve got an error:
    /usr/local/lib/python2.7/dist-packages/requests/packages/urllib3/util/ InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may certain SSL connections to fail. For more information, see
    Traceback (most recent call last):
    File “”, line 64, in

    And I don’t know why can you help me??

    • TheZippyTurtle

      Me to. Someone please help us!!

  • michael carlton

    I’m having trouble linking the APIs to the Pi I
    downloaded the code and gave it the necessary data. I used 3 Google accounts
    and all 3 didn’t work

  • 吳亦鈞

    Hi this system is very success on my RPi2 but now i have some question
    “You can easily change your origin and destination languages in the last line of ”
    So I come from Taiwan ,I want to change to Chinese
    ” os.system(“python -o en -d es -t ‘” + final_result + “‘”) ”
    Is that en and es change to ch ch?

  • C Johnson

    my pi spat out an error message along the lines of InsecurePlatformWarning
    file “” line 47 in
    KeyError: ‘access_token’
    I am new to Raspberry Pi, so I have no idea what it means. Has anyone else had the same problem?

    • TheZippyTurtle

      Me to someone please help!

  • Ash Shah

    I keep trying to test out the record of my headset but it shows

    arecord; main;682; audio open error; No such file or directory

    How to fix?

  • Hari Shankar
  • Sridhar Cp

    Joining the chromium dev group does not give access to speech api now.
    Any other alternative?