Atmel Evaluation Kit for AT32uC3A0512, 32-Bit AVR Microcontroller Atmel ATEVK1105 ATEVK1105 Data Sheet
Product codes
ATEVK1105
306
AT32UC3A
This gives a maximum baud rate of CLK_USART divided by 8, assuming that CLK_USART is
the highest possible clock and that OVER is programmed at 1.
26.7.1.2
Baud Rate Calculation Example
shows calculations of CD to obtain a baud rate at 38400 bauds for dif-
ferent source clock frequencies. This table also shows the actual resulting baud rate and the
error.
The baud rate is calculated with the following formula:
The baud rate error is calculated with the following formula. It is not recommended to work with
an error higher than 5%.
Table 26-2.
Baud Rate Example (OVER = 0)
Source Clock
Expected Baud
Rate
Calculation Result
CD
Actual Baud Rate
Error
MHz
Bit/s
Bit/s
3 686 400
38 400
6.00
6
38 400.00
0.00%
4 915 200
38 400
8.00
8
38 400.00
0.00%
5 000 000
38 400
8.14
8
39 062.50
1.70%
7 372 800
38 400
12.00
12
38 400.00
0.00%
8 000 000
38 400
13.02
13
38 461.54
0.16%
12 000 000
38 400
19.53
20
37 500.00
2.40%
12 288 000
38 400
20.00
20
38 400.00
0.00%
14 318 180
38 400
23.30
23
38 908.10
1.31%
14 745 600
38 400
24.00
24
38 400.00
0.00%
18 432 000
38 400
30.00
30
38 400.00
0.00%
24 000 000
38 400
39.06
39
38 461.54
0.16%
24 576 000
38 400
40.00
40
38 400.00
0.00%
25 000 000
38 400
40.69
40
38 109.76
0.76%
32 000 000
38 400
52.08
52
38 461.54
0.16%
32 768 000
38 400
53.33
53
38 641.51
0.63%
33 000 000
38 400
53.71
54
38 194.44
0.54%
40 000 000
38 400
65.10
65
38 461.54
0.16%
50 000 000
38 400
81.38
81
38 580.25
0.47%
60 000 000
38 400
97.66
98
38 265.31
0.35%
70 000 000
38 400
113.93
114
38 377.19
0.06%
BaudRate
CLKUSART
(
) CD
16
×
⁄
=
Error
1
ExpectedBaudRate
ActualBaudRate
----------------------------------------------------
⎝
⎠
⎛
⎞
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=
32058K
AVR32-01/12