Isosynchronous baud value =
)(
VCLK Frequency
2
Asynchronous baud value =
)(
VCLK Frequency
32
Isosynchronous baud value =
)(
VCLK Frequency
Baud + 1
Asynchronous baud value =
)(
VCLK Frequency
16(Baud + 1)
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SCI Control Registers
1751
SPNU563A–March 2018
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Serial Communication Interface (SCI) Module
30.7.11 Baud Rate Selection Register (BRS)
This section describes the baud rate selection register. Figure 30-18 and Table 30-16 illustrate this
register.
Figure 30-18. Baud Rate Selection Register (BRS) [offset = 2Ch]
31 24 23 16
Reserved BAUD
R-0 R/W-0
15 0
BAUD
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 30-16. Baud Rate Selection Register (BRS) Field Descriptions
Bit Field Value Description
31-24 Reserved 0 Reads return 0. Writes have no effect.
23-0 BAUD 0-FF FFFFh SCI 24-bit baud selection.
The SCI has an internally generated serial clock determined by the VCLK and the prescalers
BAUD in this register. The SCI uses the 24-bit integer prescaler BAUD value of this register to
select one of over 16,700,000.
The baud rate can be calculated using the following formulas:
(59)
(60)
For BAUD = 0,
(61)
(62)
Table 30-17 contains comparative baud values for different P values, with VCLK = 50 MHz, for
asynchronous mode..
(1)
VCLK = 50 MHz
(2)
Values are in decimal except for column 2.
Table 30-17. Comparative Baud Values for Different P Values, Asynchronous Mode
(1)(2)
24-Bit Register Value Baud Selected
Percent Error
Decimal Hex Ideal Actual
26 00001A 115200 115740 0.47
53 000035 57600 57870 0.47
80 000050 38400 38580 0.47
162 0000A2 19200 19172 -0.15
299 00012B 10400 10417 0.16
325 000145 9600 9586 -0.15
399 00018F 7812.5 7812.5 0.00
650 00028A 4800 4800 0.00
15624 003BA0 200 200 0.00
624999 098967 5 5 0.00
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