The UART RxD and TxD signals can be routed to one of many sets of MIO pins or to the EMIO interface. All of the modem flow control signals are always routed to the EMIO interface and are not available on the MIO pins. All of the UART signals are listed in Table: UART MIO Pins and EMIO Signals . The routing of the RxD and TxD signals are described in section PS–PL Voltage Level Shifter Enables .