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CP3BT26
22.4.2 Synchronous Mode
Synchronous mode is only available for the UART0 module.
When synchronous mode is selected and the UCKS bit is
set, the UART operates from a clock received on the CKX
pin. When the UCKS bit is clear, the UART uses the clock
from the internal baud rate generator which is also driven on
the CKX pin. When the internal baud rate generator is used,
the equation for calculating the baud rate is:
where BR is the baud rate, SYS_CLK is the System Clock,
N is the value of the baud rate divisor + 1, and P is the pres-
caler divide factor selected by the value in the UnPSR reg-
ister. Oversampling is not used in synchronous mode.
Use the same procedure to determine the values of N and
P as in the asynchronous mode. In this case, however, only
integer prescaler values are allowed.
BR
SYS_CLK
2NP××()
-----------------------------=
Table 71 Baud Rate Programming
Baud
Rate
SYS_CLK = 48 MHz SYS_CLK = 24 MHz SYS_CLK = 12 MHz SYS_CLK = 10 MHz
O N P %err O N P %err O N P %err O N P %err
300 16 2000 5.0 0.00 16 2000 2.5 0.00 16 1250 2.0 0.00 13 1282 2.0 0.00
600 16 2000 2.5 0.00 16 1250 2.0 0.00 16 1250 1.0 0.00 13 1282 1.0 0.00
1200 16 1250 2.0 0.00 16 1250 1.0 0.00 16 625 1.0 0.00 13 641 1.0 0.00
1800 7 401 9.5 0.00 8 1111 1.5 0.01 12 101 5.5 0.01 12 463 1.0 0.01
2000 16 1500 1.0 0.00 16 750 1.0 0.00 16 250 1.5 0.00 16 125 2.5 0.00
2400 16 1250 1.0 0.00 16 625 1.0 0.00 16 125 2.5 0.00 9 463 1.0 0.01
3600 8 1111 1.5 0.01 12 101 5.5 0.01 11 202 1.5 0.01 11 101 2.5 0.01
4800 16 625 1.0 0.00 16 125 2.5 0.00 10 250 1.0 0.00 7 119 2.5 0.04
7200 12 101 5.5 0.01 11 303 1.0 0.01 11 101 1.5 0.01 10 139 1.0 0.08
9600 16 125 2.5 0.00 10 250 1.0 0.00 10 125 1.0 0.00 7 149 1.0 0.13
14400 11 202 1.5 0.01 11 101 1.5 0.01 14 17 3.5 0.04 14 33 1.5 0.21
19200 10 250 1.0 0.00 10 125 1.0 0.00 10 25 2.5 0.00 16 13 2.5 0.16
38400 10 125 1.0 0.00 10 25 2.5 0.00 16 13 1.5 0.16 8 13 2.5 0.16
56000 7 49 2.5 0.04 13 33 1.0 0.10 13 11 1.5 0.10 7 17 1.5 0.04
115200 7 17 3.5 0.04 13 16 1.0 0.16 13 8 1.0 0.16 7 5 2.5 0.79
128000 15 25 1.0 0.00 15 5 2.5 0.00 11 1 8.5 0.27 12 1 6.5 0.16
230400 13 16 1.0 0.16 13 8 1.0 0.16 13 4 1.0 0.16 11 4 1.0 1.36
345600 9 1 15.5 0.44 10 7 1.0 0.79 10 1 3.5 0.79
460800 13 8 1.0 0.16 13 4 1.0 0.16 13 2 1.0 0.16 11 2 1.0 1.36
576000 8 7 1.5 0.79 12 1 3.5 0.79 14 1 1.5 0.79 7 1 2.5 0.79
691200 10 7 1.0 0.79 10 1 3.5 0.79 7 1 2.5 0.79
806400 7 1 8.5 0.04 15 2 1.0 0.79 10 1 1.5 0.79
921600 13 4 1.0 0.16 13 2 1.0 0.16 13 1 1.0 0.16
1105920 11 4 1.0 1.36 11 2 1.0 1.36 9 1 1.0 0.47
1382400 10 1 3.5 0.79 7 1 2.5 0.79
1536000 9 1 3.5 0.79 8 2 1.0 2.34