Boards Manager FAQ - kanemunelab/Arduino GitHub Wiki

How is the boards list generated?

Arduino maintains the list and updates it every time a new core or tool or board definition is updated.

Can I add my own URL with my own boards list?

As of Arduino IDE version 1.6.4 you can add them at File > Preferences > Additional Boards Manager URLs. You can see examples of how this is done, find other 3rd party boards, and add yours to the list here: https://github.com/arduino/Arduino/wiki/Unofficial-list-of-3rd-party-boards-support-urls

I can't delete one of the cores!

Built-in cores cannot be deleted: they are part of the minimum setup provided by the IDE. However, if the built-in version is giving you troubles and a newer (or an older) one would solve your issue, you can upgrade (or even downgrade) a core, choosing one of the available versions

Where are installed cores located?

• On GNU/Linuxes: ~/.arduino15/packages/
• On Windows: %APPDATA%\Arduino15\packages\
• On MacOSXes: ~/Library/Arduino15/packages/

On Windows if you create a folder named portable right inside the arduino main folder, all packages, libraries and sketches will be stored there, thus keeping everything in one place. Great if you have your arduino on a USB flash drive or in dropbox synced over multiple PC

Where can I put platform.local.txt?

platform.local.txt is a way to customize some of the parameters in platform.txt, without touching platform.txt (which is quite crowded with params, thus hard to compare with the original once it's modified).

With Boards Manager, platforms (boards and tools) can be installed in different locations: IDE hardware folder, or a subfolder of the local packages folder (see question above), for example ~/.arduino15/packages/arduino/hardware/.

Locate the folder with the toolchain you want to customize and place a platform.local.txt file next to platform.txt. Don't forget to make a backup copy of that file: it will be deleted when you'll upgrade that platform.