Software flow control configuration
| SW_FLOW_CON_EN | Set this bit to enable software flow control. When UART receives flow control characters XON or XOFF, which can be configured by UART_XON_CHAR or UART_XOFF_CHAR respectively, UART_SW_XON_INT or UART_SW_XOFF_INT interrupts can be triggered if enabled. |
| XONOFF_DEL | Set this bit to remove flow control characters from the received data. |
| FORCE_XON | Set this bit to force the transmitter to send data. |
| FORCE_XOFF | Set this bit to stop the transmitter from sending data. |
| SEND_XON | Set this bit to send an XON character. This bit is cleared by hardware automatically. |
| SEND_XOFF | Set this bit to send an XOFF character. This bit is cleared by hardware automatically. |