9.3.2.4.5 Chip Erase Command
 The Chip Erase (CHER) command erases the Flash and the EEPROM. The EEPROM is unaltered if
         the EEPROM Save During Chip Erase (EESAVE) fuse in FUSE.SYSCFG0 is set. The Flash will not
         be protected by Boot Section Lock (BOOTLOCK) bit or Application Code Section Write
         Protection (APCWP) bit in NVMCTRL.CTRLB register. The memory will be all
            ‘1’s after the operation.
