Texas Instruments MSP430x1xx - Manual (Page 218)

USART Peripheral Interface
12-2
12.1 USART Peripheral Interface
The USART peripheral interface connects to the CPU as a byte peripheral
module. It connects the MSP430 to the external system environment with
three or four external pins. Figure 12–1 shows the USART peripheral interface
module.
Figure 12–1. Block Diagram of USART
0
Receive Buffer URXBUF
SSEL0 SSEL1
UCLKI
ACLK
1
2
3
WUT
CKPH
Receive Shift Register
Receive Status
0
SYNC
SYNC
Baud Rate Generator
Baud Rate Register UBR
Baud Rate Generator
SYNC SYNC
SYNC
UCLKS
Transmit Shift Register
Transmit Buffer UTXBUF
0
1
1
0
1
0
Clock Phase and Polarity
SYNC CKPL
UCLKI
UCLKS
UCLK
SIMO
UTXD
STE
URXD
SOMI
MM Listen
SYNC RXE
TXWake
SMCLK
SMCLK