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Arduino IDE 1.6.6 released and available for download

Martino FacchinNovember 3rd, 2015

Screenshot 2015-11-03 12.27.18

Today we are very proud to release Arduino IDE 1.6.6 and updated cores for all supported platforms (AVR 1.6.9, SAM 1.6.5, SAMD 1.6.2)

This update brings an impressive 723 closed issues and 147 pull requests merged.

Most intriguing features are:

  • Long-awaited new arduino-builder: this is a pure command-line tool which takes care of mangling the code, resolving library dependencies and setting up the compilation units. It can also be used as a standalone program in a continuous-integration environment
  • Pluggable USB core: your Arduino can finally act as a lot of different USB devices without any need to change the core, thanks to the new modular architecture. Libraries based on the new subsystem are already being developed!
  • Serial plotter: you can now plot your data in realtime, as easy as writing Serial.println(analogRead(A0)) inside your loop



  • New goodies for library developers, like unlocked examples while developing and optional linkage into an archive
  • ArduinoISP example has been improved a lot and now you can flash your AVR chip using ANY other board (including third-party ones 🙂 )
  • Both Libraries and Boards managers notify if a library/core can be updated with a simple popup – no more outdated code floating around!
  • A LOT of bug fixes, adjustments, documentation refinement thanks to our tireless users and contributors. The complete list of fixes and credits is available here.

Don’t forget to report any issue you find, either on Github or on the Arduino forum: your help is very much appreciated. It doesn’t matter if you are not a tech specialist: every feedback adds value.

Happy coding!


16 Responses to “Arduino IDE 1.6.6 released and available for download”

  1. mitov Says:

    This version appears to have a large number of serious bugs. I would recommend using the 1.6.5 until the bugs are fixed. I have already reported one of the most critical bugs, but I will probably report some more as even such essential functionality such as file association seems to be broken at least in Windows 7 🙁

  2. Mostdanger Says:

    I have confirmed the ‘namespace’ bug affects the release version as does the file association bug, in win 7 and 8!

    You shouldn’t by too, proud of this release!

  3. mitov Says:

    I would recommend if possible this version to be reverted back to Beta, and the official to be returned to 1.6.5 until this version gets fixed. This is the worst version that I have seen since I have started using Arduino and has a number of critical bugs 🙁

  4. Federico Fissore Says:

    mitov and Mostdanger, thank you for letting us know of the issue even on github, here and here respectevely
    mitov, as you can read in my comment, I’ve asked you help in debugging your issue. It is not related to file association, otherwise the IDE would even try to open.
    Mostdanger, I confirmed the regression: it will be fixed in one of the hourly builds and become part of IDE 1.6.7
    Thank you both for your feedback!

  5. ocwo92 Says:

    I had serious compile problems on Linux, too. Please remove this release until it has been properly tested.

  6. Federico Fissore Says:

    ocwo92 please report any issue you’re facing with as much detail as possible. that will help us supporting you or fixing problems

  7. MartinN Says:

    I tried to recompile a couple of my programs with the new 1.6.6 version (incl library & boards updates).
    However I encountered several problems, basically several programs do not compile anymore
    I then tried to compile a couple of the library examples and same behaviour 🙁
    For example:

    I opened library example: Time | TimeNTP (library version 1.4.0)
    I tried to compile for Arduino Zero (worked fine previously)
    Now lots of compile and link errors

    I opened library example: DS1307RTC | SetTime (library version 1.4.0)
    I tried to compile for Arduino Zero (worked fine previously)
    Now lots of compile and link errors

    I opened library example: TFT | TFTDisplayText (library version 1.0.5)
    I tried to compile for Arduino Zero
    Still compile errors

    Any suggestions for fixes?

  8. the-fallen Says:

    And still no support for UHD Displays… sadly.

  9. Federico Fissore Says:

    MartinN, sorry to read that. Can you open an issue on with the actual error message? Or copy paste them and send me an email at
    Thank you!

  10. Federico Fissore Says:

    the-fallen, sorry about that. UHD support will come in one of next releases

  11. Martino Facchin Says:

    Hi MartinN, I’ve just tested RTC and Time libraries using the nightly ( and Zero core 1.6.2 and they all compile correctly. Could you test with that version and report if your sketches still fail compiling? TFT instead tries to include an AVR specific file, so it needs to be patched in order to compile with the Zero.

  12. meph328 Says:

    Hi, I have dowload the new 1.6.6 version and when i use the libary LiquidCrytal_I2C for LCD.
    The printing text only shows the first letter of the text
    On others version before works fine.

  13. AlanTJohnstone Says:

    I tried compiling a program that looks for #include
    It compiles for the Uno but not for the Due saying that it cannot find the file

  14. queenidog Says:

    I haven’t downloaded based on the comments so far. Thanks to you guys who have done so…saves a lot of us headaches! I don’t know how the GUI may have changed but I hope it has been updated to UECIDE parameters, the program that raised the bar for Arduino IDEs. AND, PLEASE fix the print sketch system so that printing is WYSIWYG.

  15. Ney5 Says:

    Manual de ploter

  16. Nova versão da IDE Arduino disponível Says:

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