Status register
| TX_BUSY | Read-only flag indicating the UART transmit status |
| RX_BUSY | Read-only flag indicating the UART receiver status |
| RX_EM | Read-only flag indicating the RX FIFO state |
| RX_FULL | Read-only flag indicating the RX FIFO state |
| TX_EM | Read-only flag indicating the TX FIFO state |
| TX_FULL | Read-only flag indicating the TX FIFO state |
| RX_LVL | Indicates the number of bytes currently in the RX FIFO (0-RX FIFO_ELTS) |
| TX_LVL | Indicates the number of bytes currently in the TX FIFO (0-TX FIFO_ELTS) |