Table 12-56 lists the UART interface input/output (I/O) signals.
Table 12-56 UART I/O SignalsModule Pin Name | Device Level Signal Name | I/O(1) | Description | Module Pin Reset Value(2) |
---|
WKUP_UARTi(10) |
RX |
WKUP_UARTi(10)_RXD |
I |
Serial data input |
HiZ |
TX |
WKUP_UARTi(10)_TXD |
O |
Serial data output(3) |
1 |
CTS |
WKUP_UARTi(10)_CTS |
I |
Clear to send(4) |
HiZ |
RTS |
WKUP_UARTi(10)_RTS |
O |
Request to send(5) |
1 |
MCU_UARTi(10) |
RX | MCU_UARTi(10)_RXD | I | Serial data input | HiZ |
TX | MCU_UARTi(10)_TXD | O | Serial data output(3) | 1 |
CTS | MCU_UARTi(10)_CTS | I | Clear to send(4) | HiZ |
RTS | MCU_UARTi(10)_RTS | O | Request to send(5) | 1 |
UARTi(10) Modem Signals |
DCD | UARTi(10)_DCDn | I | Data Carrier Detect(6) | HiZ |
DSR | UARTi(10)_DSRn | I | Data Set Ready(7) | HiZ |
DTR | UARTi(10)_DTRn | O | Data Terminal Ready(8) | 1 |
RIN | UARTi(10)_RIN | I | Ring Indicator(9) | HiZ |
(1) I = Input; O = Output
(2) HiZ = High Impedance
(3) Because this pin is active high in IrDA mode and the output is muxed,
this pin is set to low on reset (when the UART_MDR1[2-0] bit field is set to 0x7) and
takes the defined inactive level of that signal corresponding to when and how the
UART_MDR1 register is programmed; that is, the output is 1 (inactive for UART modem modes)
and 0 (inactive for IrDA modes).
(4) Active-low modem status signal. Reading the UART_MSR[4] NCTS_STS bit
checks the condition of CTS. Reading the UART_MSR[0] CTS_STS bit checks a change of state
of CTS since the last read of the modem status register. The auto-CTS mode uses CTS to
control the transmitter.
(5) When active (low), the module is ready to receive data. Setting the
UART_MCR[1] RTS bit activates RTS signal, which becomes inactive as the result of a module
reset, loopback mode, or clearing the UART_MCR[1] RTS bit. In auto-RTS mode, RTS signal
becomes inactive as a result of the receiver threshold logic.
(6) Active-low modem status signal. The condition of DCD can be checked by
reading the UART_MSR[7] NCD_STS bit. Any change in its state can be detected by reading
the UART_MSR[3] DCD_STS bit.
(7) Active-low modem status signal. Reading the UART_MSR[5] NDSR_STS bit
checks the condition of DSR. Reading the UART_MSR[1] DSR_STS bit checks a change of state
of DSR since the last read of the UART_MSR register.
(8) When active (low), this signal informs the modem that the module is
ready to communicate. It is activated by setting the UART_MCR[0] DTR bit.
(9) Active-low modem status signal. The condition of RIN can be checked by
reading the UART_MSR[6] NRI_STS bit. Any change in its state can be detected by reading
the UART_MSR[2] RI_STS bit.
(10) i represents a UART instance. See the device datasheet for available domains
and UART instances.
Note: For more information about device level signals (pull-up/down resistors, buffer type, multiplexing and others), see tables Pin Attributes and Pin Multiplexing in the device-specific Datasheet.