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