Add board to Arduino building

I’m using an Atmega1248 with arduino support added through GitHub - MCUdude/MightyCore: Arduino hardware package for ATmega1284, ATmega644, ATmega324, ATmega324PB, ATmega164, ATmega32, ATmega16 and ATmega8535 I’m wondering what the easiest way to add an extra hardware section into PlatformIO is? I don’t see a place like in the Arduino IDE to upload my own hardware folder.

We have an issue for that MightyCore Boards Support · Issue #585 · platformio/platformio-core · GitHub.

Place your core to ~/.platformio/packages/framework-arduinoavr/cores.