I have an Arduino based board using ATmega168PB, but so far only Atmel's provided toolchain supports this microcontroller. I can download the toolchain from Atmel's website, but I am not sure how to make the Arduino environment use it.
In the directory for the new core create a new platform.txt
and give the entry for compiler.path
the location of the bin/
directory containing the Atmel toolchain.
compiler.path=/path/to/bin/