Техническая Спецификация для Atmel Evaluation Kit for AT32uC3A0512, 32-Bit AVR Microcontroller Atmel ATEVK1105 ATEVK1105
Модели
ATEVK1105
308
AT32UC3A
has no effect. The external clock frequency must be at least 4.5 times lower than the system
clock.
When either the external clock CLK or the internal clock divided (CLK_USART/DIV) is selected,
When either the external clock CLK or the internal clock divided (CLK_USART/DIV) is selected,
the value programmed in CD must be even if the user has to ensure a 50:50 mark/space ratio on
the CLK pin. If the internal clock CLK_USART is selected, the Baud Rate Generator ensures a
50:50 duty cycle on the CLK pin, even if the value programmed in CD is odd.
26.7.1.5
Baud Rate in ISO 7816 Mode
The ISO7816 specification defines the bit rate with the following formula:
where:
•B is the bit rate
•Di is the bit-rate adjustment factor
•Fi is the clock frequency division factor
•f is the ISO7816 clock frequency (Hz)
•Di is the bit-rate adjustment factor
•Fi is the clock frequency division factor
•f is the ISO7816 clock frequency (Hz)
Di is a binary value encoded on a 4-bit field, named DI, as represented in
.
Fi is a binary value encoded on a 4-bit field, named FI, as represented in
.
shows the resulting Fi/Di Ratio, which is the ratio between the ISO7816
clock and the baud rate clock.
If the USART is configured in ISO7816 Mode, the clock selected by the USCLKS field in the
Mode Register (MR) is first divided by the value programmed in the field CD in the Baud Rate
B
Di
Fi
-------
f
×
=
Table 26-3.
Binary and Decimal Values for Di
DI field
0001
0010
0011
0100
0101
0110
1000
1001
Di (decimal)
1
2
4
8
16
32
12
20
Table 26-4.
Binary and Decimal Values for Fi
FI field
0000
0001
0010
0011
0100
0101
0110
1001
1010
1011
1100
1101
Fi (decimal
372
372
558
744
1116
1488
1860
512
768
1024
1536
2048
Table 26-5.
Possible Values for the Fi/Di Ratio
Fi/Di
372
558
774
1116
1488
1806
512
768
1024
1536
2048
1
372
558
744
1116
1488
1860
512
768
1024
1536
2048
2
186
279
372
558
744
930
256
384
512
768
1024
4
93
139.5
186
279
372
465
128
192
256
384
512
8
46.5
69.75
93
139.5
186
232.5
64
96
128
192
256
16
23.25
34.87
46.5
69.75
93
116.2
32
48
64
96
128
32
11.62
17.43
23.25
34.87
46.5
58.13
16
24
32
48
64
12
31
46.5
62
93
124
155
42.66
64
85.33
128
170.6
20
18.6
27.9
37.2
55.8
74.4
93
25.6
38.4
51.2
76.8
102.4
32058K
AVR32-01/12