Texas Instruments MSP430x1xx - Page 283

USART Registers: UART Mode
13-23
USART Peripheral Interface, UART Mode
UxTCTL, USART Transmit Control Register
76543210
Unused CKPL SSELx URXSE TXWAKE Unused TXEPT
rw−0 rw−0 rw−0 rw−0 rw−0 rw−0 rw−0 rw−1
Unused
Bit 7 Unused
CKPL
Bit 6 Clock polarity select
0 UCLKI = UCLK
1 UCLKI = inverted UCLK
SSELx
Bits
5-4
Source select. These bits select the BRCLK source clock.
00 UCLKI
01 ACLK
10 SMCLK
11 SMCLK
URXSE
Bit 3 UART receive start-edge. The bit enables the UART receive start-edge
feature.
0 Disabled
1 Enabled
TXWAKE
Bit 2 Transmitter wake
0 Next character transmitted is data
1 Next character transmitted is an address
Unused
Bit 1 Unused
TXEPT
Bit 0 Transmitter empty flag
0 UART is transmitting data and/or data is waiting in UxTXBUF
1 Transmitter shift register and UxTXBUF are empty or SWRST=1