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M0A21/M0A23 Series
May 06, 2022
Page
498
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
PB.4, PB.5, PB.6, PB.7
PC.0, PC.1, PC.2, PC.3, PC.4, PC.5, PC.6,
PC.7
USCI1_DAT1
PD.2
MFP4
PA.0, PA.1, PA.2, PA.4, PA.5
PB.4, PB.5, PB.6, PB.7
PC.0, PC.1, PC.2, PC.3, PC.4, PC.5, PC.6,
PC.7
MFP17
6.13.5 Functional Description
USCI Common Function Description
Please refer to section 6.12.4 for detailed information.
Signal Description
An UART connection is characterized by the use of a single connection line between a transmitter and
a receiver. The receiver input signal (RXD) is handled by the input stage USCIx_DAT0 and the transmit
output (TXD) signal is handled by the output stage of USCIx_DAT1.
For full-duplex communication, an independent communication line is needed for each transfer direction.
Figure 6.13-2 shows an example with a point-to-point full-duplex connection between two
communication partners UART module A and UART module B.
RX_BUF
TX_BUF
Transfer
Control
Baud Rate
Generator
UART Module A
f
PCLK
USCIx_DAT0
USCIx_DAT1
RX_BUF
TX_BUF
Transfer
Control
Baud Rate
Generator
UART Module B
f
PCLK
USCIx_DAT0
USCIx_DAT1
RXD
TXD
TXD
RXD
Figure 6.13-2 UART Signal Connection for Full-Duplex Communication
Input Signals
For UART protocol, the number of input signals is shown in Table 6.13-1. Each input signal is handled
by an input processor for signal conditioning, such as signal inverse selection control, or a digital input
filter. They can be classified according to their meaning for the protocols (see Table 6.13-1).
Selected Protocol
UART
Control Input
USCIx_CTL0
nCTS
USCIx_CTL1
X
Data Input
USCIx_DAT0
RX