Interrupt Mask Register
| RXRDY | Mask RXRDY Interrupt |
| TXRDY | Disable TXRDY Interrupt |
| ENDRX | Mask End of Receive Transfer Interrupt |
| ENDTX | Mask End of Transmit Interrupt |
| OVRE | Mask Overrun Error Interrupt |
| FRAME | Mask Framing Error Interrupt |
| PARE | Mask Parity Error Interrupt |
| TXEMPTY | Mask TXEMPTY Interrupt |
| TXBUFE | Mask TXBUFE Interrupt |
| RXBUFF | Mask RXBUFF Interrupt |