Clock control register
| HICKEN | High speed internal clock enable |
| HICKSTBL | High speed internal clock ready flag |
| HICKTRIM | High speed internal clock trimming |
| HICKCAL | High speed internal clock calibration |
| HEXTEN | High speed exernal crystal enable |
| HEXTSTBL | High speed exernal crystal ready flag |
| HEXTBYPS | High speed exernal crystal bypass |
| CFDEN | Clock failure detection enable |
| PLLEN | PLL enable |
| PLLSTBL | PLL clock ready flag |