Flash control register
| PG | Programming  |  
| PER | Page erase  |  
| MER | Mass erase  |  
| OPTPG | Option byte programming  |  
| OPTER | Option byte erase  |  
| STRT | Start  |  
| LOCK | Lock  |  
| OPTWRE | Option bytes write enable  |  
| ERRIE | Error interrupt enable  |  
| EOPIE | End of operation interrupt enable  |  
| FORCE_OPTLOAD | Force option byte loading  |