TxFIFO
16 x8
.
.
.
RxFIFO
16 x8
.
.
.
DMA Control
UARTDMACTL
Identification
Registers
UARTPCellID0
UARTPCellID1
UARTPCellID2
UARTPCellID3
UARTPeriphID0
UARTPeriphID1
UARTPeriphID2
UARTPeriphID3
UARTPeriphID4
UARTPeriphID5
UARTPeriphID6
UARTPeriphID7
Interrupt Control
UARTDR
Control/Status
Transmitter
(with SIR
Transmit
Encoder)
Baud Rate
Generator
Receiver
(with SIR
Receive
Decoder)
UnTx
UnRx
DMA Request
System Clock
Interrupt
UARTIFLS
UARTIM
UARTMIS
UARTRIS
UARTICR
UARTIBRD
UARTFBRD
UARTRSR/ECR
UARTFR
UARTLCRH
UARTCTL
UARTILPR
UARTLCTL
UARTLSS
UARTLTIM
Functional Description
1453
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
M3 Universal Asynchronous Receivers/Transmitters (UARTs)
Figure 21-1. UART Module Block Diagram
21.3 Functional Description
Each UART performs the functions of parallel-to-serial and serial-to-parallel conversions. It is similar in
functionality to a 16C550 UART, but is not register-compatible.
The UART is configured for transmit and/or receive via the TXE and RXE bits of the UART Control
(UARTCTL) register. Transmit and receive are both enabled out of reset. Before any control registers are
programmed, the UART must be disabled by clearing the UARTEN bit in UARTCTL. If the UART is
disabled during a TX or RX operation, the current transaction is completed prior to the UART stopping.
The UART module also includes a serial IR (SIR) encoder/decoder block that can be connected to an
infrared transceiver to implement an IrDA SIR physical layer. The SIR function is programmed using the
UARTCTL register.
21.3.1 Transmit/Receive Logic
The transmit logic performs parallel-to-serial conversion on the data read from the transmit FIFO. The
control logic outputs the serial bit stream beginning with a start bit and followed by the data bits (LSB first),
parity bit, and the stop bits according to the programmed configuration in the control registers. See
for details.