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 |
| DBN0 | low bit for Data bit num |
| UEN | USART enable |
| CMDIE | Character match detection interrupt enable |
| TCDT | transmit complete delay time |
| TSDT | transmit start delay time |
| RETODIE | Receiver time out detection interrupt enable |
| RTODEN | Receiver time out detection enable |
| DBN1 | high bit for Data bit num |