Texas Instruments MSP430x1xx - Manual (Page 248)

13-2
13.1 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 13–1 shows the USART peripheral-interface
module
Figure 13–1. Block Diagram of USART
0
Receive Buffer URXBUF
SSEL0 SSEL1
UCLKI
ACLK
SMCLK
1
2
3
SMCLK
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