eUSCI_A Operation – UART Mode
919
SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
Enhanced Universal Serial Communication Interface (eUSCI) – UART Mode
Table 24-5. Recommended Settings for Typical Crystals and Baud Rates
(1)
(continued)
BRCLK
Baud Rate
UCOS16
UCBRx
UCBRFx
UCBRSx
TX Error
(2)
(%)
RX Error
(2)
(%)
neg
pos
neg
pos
8388608
230400
1
2
4
0x92
-1.62
1.37
-3.56
2.06
8388608
460800
0
18
–
0x11
-2
3.37
-5.31
5.55
12000000
9600
1
78
2
0x0
0
0
0
0.04
12000000
19200
1
39
1
0x0
0
0
0
0.16
12000000
38400
1
19
8
0x65
-0.16
0.16
-0.4
0.24
12000000
57600
1
13
0
0x25
-0.16
0.32
-0.48
0.48
12000000
115200
1
6
8
0x20
-0.48
0.64
-1.04
1.04
12000000
230400
1
3
4
0x2
-0.8
0.96
-1.84
1.84
12000000
460800
1
1
10
0x0
0
1.76
0
3.44
16000000
9600
1
104
2
0xD6
-0.04
0.02
-0.09
0.03
16000000
19200
1
52
1
0x49
-0.08
0.04
-0.1
0.14
16000000
38400
1
26
0
0xB6
-0.08
0.16
-0.28
0.2
16000000
57600
1
17
5
0xDD
-0.16
0.2
-0.3
0.38
16000000
115200
1
8
10
0xF7
-0.32
0.32
-1
0.36
16000000
230400
1
4
5
0x55
-0.8
0.64
-1.12
1.76
16000000
460800
1
2
2
0xBB
-1.44
1.28
-3.92
1.68
16777216
9600
1
109
3
0xB5
-0.03
0.02
-0.05
0.06
16777216
19200
1
54
9
0xEE
-0.06
0.06
-0.11
0.13
16777216
38400
1
27
4
0xFB
-0.11
0.1
-0.33
0
16777216
57600
1
18
3
0x44
-0.16
0.15
-0.2
0.45
16777216
115200
1
9
1
0xB5
-0.31
0.31
-0.53
0.78
16777216
230400
1
4
8
0xEE
-0.75
0.74
-2
0.87
16777216
460800
1
2
4
0x92
-1.62
1.37
-3.56
2.06
20000000
9600
1
130
3
0x25
-0.02
0.03
0
0.07
20000000
19200
1
65
1
0xD6
-0.06
0.03
-0.1
0.1
20000000
38400
1
32
8
0xEE
-0.1
0.13
-0.27
0.14
20000000
57600
1
21
11
0x22
-0.16
0.13
-0.16
0.38
20000000
115200
1
10
13
0xAD
-0.29
0.26
-0.46
0.66
20000000
230400
1
5
6
0xEE
-0.67
0.51
-1.71
0.62
20000000
460800
1
2
11
0x92
-1.38
0.99
-1.84
2.8
24.3.14 Using the eUSCI_A Module in UART Mode With Low-Power Modes
The eUSCI module is not functional when the device is in LPM3, LPM4, or LPMx.5 modes of operation.
However, the application can make use of the FORCE_LPM_ENTRY bit in the PCMCTL1 register to
determine whether the entry to low-power mode should be aborted if the eUSCI is active, or if the device
can continue low power entry regardless. The latter option is useful if the eUSCI is transmitting or
receiving data at a very slow rate, and the application should enter low-power mode at the expense of a
packet of data being lost. Refer to the
Power Control Manager (PCM)
chapter for more details.
24.3.15 eUSCI_A Interrupts
The eUSCI_A has only one interrupt vector that is shared for transmission and for reception.
24.3.15.1 eUSCI_A Transmit Interrupt Operation
The UCTXIFG interrupt flag is set by the transmitter to indicate that UCAxTXBUF is ready to accept
another character. An interrupt request is generated if UCTXIE is set. UCTXIFG is automatically reset if a
character is written to UCAxTXBUF.