Control register 1
| SBF | Send break frame |
| RM | Receiver mute |
| REN | Receiver enable |
| TEN | Transmitter enable |
| IDLEIEN | IDLE interrupt enable |
| RDBFIEN | RDBF interrupt enable |
| TDCIEN | TDC interrupt enable |
| TDBEIEN | TDBE interrupt enable |
| PERRIEN | PERR interrupt enable |
| PSEL | Parity selection |
| PEN | Parity enable |
| WUM | Wake up mode |
| DBN | Data bit num |
| UEN | USART enable |