eUSCI_A Operation – UART Mode
783
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
Enhanced Universal Serial Communication Interface (eUSCI) – UART Mode
Table 30-5. Recommended Settings for Typical Crystals and Baud Rates
(1)
(continued)
BRCLK
Baud Rate
UCOS16
UCBRx
UCBRFx
UCBRSx
(2)
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
30.3.14 Using the eUSCI_A Module in UART Mode With Low-Power Modes
The eUSCI_A module provides automatic clock activation for use with low-power modes. When the
eUSCI_A clock source is inactive because the device is in a low-power mode, the eUSCI_A module
automatically activates it when needed, regardless of the control-bit settings for the clock source. The
clock remains active until the eUSCI_A module returns to its idle condition. After the eUSCI_A module
returns to the idle condition, control of the clock source reverts to the settings of its control bits.
NOTE:
Clock Activation Time
If the clock source is not already active when the eUSCI_A module requests it then the clock
must be activated. This takes time. This clock activation time depending on the selected
clock source and the selected low power mode. If the DCO is used as clock source the
activation time is approximately the wake-up time as specified in the device-specific data
sheet.