avr51 - enhanced AVR core with up to 128K program memory
                   avr6  - enhanced AVR core with up to 256K program memory
                   avrxmega3 - XMEGA, > 8K, <= 64K FLASH, > 64K RAM
                   avrxmega4 - XMEGA, > 64K, <= 128K FLASH, <= 64K RAM
                   avrxmega5 - XMEGA, > 64K, <= 128K FLASH, > 64K RAM
                   avrxmega6 - XMEGA, > 128K, <= 256K FLASH, <= 64K RAM
                   avrxmega7 - XMEGA, > 128K, <= 256K FLASH, > 64K RAM
                   or immediate microcontroller name.