803
11054A–ATARM–27-Jul-11
SAM9X25
803
11054A–ATARM–27-Jul-11
SAM9X25
This gives a maximum baud rate of MCK divided by 8, assuming that MCK is the highest possi-
ble clock and that OVER is programmed to 1.
Baud Rate Calculation Example
shows calculations of CD to obtain a baud rate at 38400 bauds for different 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%.
Baudrate
SelectedClock
8 2
Over
–
(
)
CD
(
)
--------------------------------------------
=
Table 39-5.
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%
BaudRate
MCK
CD
16
×
⁄
=
Error
1
ExpectedBaudRate
ActualBaudRate
---------------------------------------------------
⎝
⎠
⎛
⎞
–
=
Содержание SAM9X25
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Страница 1067: ...1067 11054A ATARM 27 Jul 11 SAM9X25 1067 11054A ATARM 27 Jul 11 SAM9X25 PTZ Pause Time Zero Enable pause time zero interrupt...
Страница 1069: ...1069 11054A ATARM 27 Jul 11 SAM9X25 1069 11054A ATARM 27 Jul 11 SAM9X25 PTZ Pause Time Zero Disable pause time zero interrupt...
Страница 1071: ...1071 11054A ATARM 27 Jul 11 SAM9X25 1071 11054A ATARM 27 Jul 11 SAM9X25 PTZ Pause Time Zero Pause time zero interrupt masked...
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Страница 1131: ...1131 11054A ATARM 27 Jul 11 SAM9X25 Revision History Doc Rev 11054A Comments Change Request Ref 1st issue...
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