Flash control register
| PG | Programming |
| PER | Page erase |
| MER | This bit triggers the mass erase (all user pages) when set |
| PNB | Page number selection |
| STRT | Start |
| OPTSTRT | Options modification start |
| FSTPG | Fast programming |
| EOPIE | End of operation interrupt enable |
| ERRIE | Error interrupt enable |
| RDERRIE | PCROP read error interrupt enable |
| OBL_LAUNCH | Force the option byte loading |
| OPTLOCK | Options Lock |
| LOCK | FLASH_CR Lock |