Interrupt mask register
| TX_TRIGGER | Mask bit for corresponding bit in interrupt request register. |
| TX_NOT_FULL | Mask bit for corresponding bit in interrupt request register. |
| TX_EMPTY | Mask bit for corresponding bit in interrupt request register. |
| TX_OVERFLOW | Mask bit for corresponding bit in interrupt request register. |
| TX_UNDERFLOW | Mask bit for corresponding bit in interrupt request register. |
| TX_WD | Mask bit for corresponding bit in interrupt request register. |
| RX_TRIGGER | Mask bit for corresponding bit in interrupt request register. |
| RX_NOT_EMPTY | Mask bit for corresponding bit in interrupt request register. |
| RX_FULL | Mask bit for corresponding bit in interrupt request register. |
| RX_OVERFLOW | Mask bit for corresponding bit in interrupt request register. |
| RX_UNDERFLOW | Mask bit for corresponding bit in interrupt request register. |
| RX_WD | Mask bit for corresponding bit in interrupt request register. |