Control register 3
| EIE | Error interrupt enable |
| HDSEL | Half-duplex selection |
| DMAR | DMA enable receiver |
| DMAT | DMA enable transmitter |
| RTSE | RTS enable |
| CTSE | CTS enable |
| CTSIE | CTS interrupt enable |
| OVRDIS | Overrun Disable |
| DDRE | DMA Disable on Reception Error |
| DEM | Driver enable mode |
| DEP | Driver enable polarity selection |
| TXFTIE | TXFTIE |
| RXFTCFG | RXFTCFG |
| RXFTIE | RXFTIE |
| TXFTCFG | TXFTCFG |