Register for wake up flags. All bits in this register are write 1 to clear.
| TXTHRLD | Wake on TX FIFO Threshold Crossed. 1 (clear): Flag is set when value read is 1. Write 1 to clear this flag. |
| TXEMPTY | Wake on TX FIFO Empty. 1 (clear): Flag is set when value read is 1. Write 1 to clear this flag. |
| RXTHRLD | Wake on RX FIFO Threshold Crossed. 1 (clear): Flag is set when value read is 1. Write 1 to clear this flag. |
| RXFULL | Wake on RX FIFO Full. 1 (clear): Flag is set when value read is 1. Write 1 to clear this flag. |