Texas Instruments MSP430x1xx - Manual (Page 219)

USART Peripheral Interface, UART Mode
12-3
USART Peripheral Interface, UART Mode
12.2 USART Peripheral Interface, UART Mode
The USART peripheral interface is a serial channel that shifts a serial bit
stream of 7 or 8 bits in and out of the MSP430. The UART mode is chosen
when control bit SYNC in the USART control register (UCTL) is reset.
12.2.1 UART Serial Asynchronous Communication Features
Some of the UART features include:
- Asynchronous formats that include idle line/address bit-communication
protocols
- Two shift registers that shift a serial data stream into URXD and out of
UTXD
- Data that is transmitted/received with the LSB first
- Programmable transmit and receive bit rates
- Status flags
Figure 12–2 shows the USART in UART mode.
Figure 12–2. Block Diagram of USART—UART Mode
0
Receive Buffer URXBUF
SSEL0 SSEL1
UCLKI
ACLK
1
2
3
WUT
Receive Shift Register
Receive Status
LSB First
Baud Rate Generator
Baud Rate Register UBR
Baud Rate Generator
UCLKS
Transmit Shift Register
Transmit Buffer UTXBUF
0
1
Clock Polarity
CKPL
UCLKI
UCLKS
UCLK
URXD
SYNC = 0
Listen
RXE
TXWake
UTXD
SMCLK
SMCLK