atmega103 ATMEL Corporation, atmega103 Datasheet - Page 74

• Manufacturer Part Number: atmega103
• Description: Atmega103 8-bit With 128k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Table 24. UBRR Settings at Various CPU Frequencies
UART Baud Rate Register –
UBRR
74
ATmega103(L)
Baud Rate
Baud Rate
Baud Rate
115200 UBRR=
115200 UBRR=
115200 UBRR=
14400 UBRR=
19200 UBRR=
28800 UBRR=
38400 UBRR=
57600 UBRR=
76800 UBRR=
14400 UBRR=
19200 UBRR=
28800 UBRR=
38400 UBRR=
57600 UBRR=
76800 UBRR=
14400 UBRR=
19200 UBRR=
28800 UBRR=
38400 UBRR=
57600 UBRR=
76800 UBRR=
2400 UBRR=
4800 UBRR=
9600 UBRR=
2400 UBRR=
4800 UBRR=
9600 UBRR=
2400 UBRR=
4800 UBRR=
9600 UBRR=
3.2768 MHz %Error
7.3728 MHz %Error
1 MHz %Error
191
25
12
84
42
20
13
10
95
47
31
23
15
11
The UBRR is an 8-bit read/write register that specifies the UART baud rate according to
the description on the previous page.
6
3
2
1
1
0
0
0
6
4
3
2
1
7
5
3
Bit
$09 ($29)
Read/Write
Initial Value
22.9 UBRR=
22.9 UBRR=
84.3 UBRR=
12.5 UBRR=
12.5 UBRR=
12.5 UBRR=
0.2 UBRR=
0.2 UBRR=
7.5 UBRR=
7.8 UBRR=
7.8 UBRR=
7.8 UBRR=
7.8 UBRR=
0.4 UBRR=
0.8 UBRR=
1.6 UBRR=
1.6 UBRR=
3.1 UBRR=
1.6 UBRR=
6.3 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
1.8432 MHz %Error
3.6864 MHz %Error
MSB
R/W
7
0
8 MHz %Error
207
103
47
23
11
95
47
23
15
11
51
34
25
16
12
7
5
3
2
1
1
0
7
5
3
2
1
8
6
3
R/W
6
0
33.3 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.2 UBRR=
0.2 UBRR=
0.2 UBRR=
0.8 UBRR=
0.2 UBRR=
2.1 UBRR=
0.2 UBRR=
3.7 UBRR=
7.5 UBRR=
7.8 UBRR=
R/W
5
0
9.216 MHz %Error
2 MHz %Error
4 MHz %Error
R/W
4
0
103
239
119
51
25
12
51
25
16
12
59
39
29
19
14
8
6
3
2
1
1
0
8
6
3
2
1
9
7
4
R/W
3
0
22.9 UBRR=
0.2 UBRR=
0.2 UBRR=
0.2 UBRR=
3.7 UBRR=
7.5 UBRR=
7.8 UBRR=
7.8 UBRR=
7.8 UBRR=
7.8 UBRR=
0.2 UBRR=
0.2 UBRR=
0.2 UBRR=
2.1 UBRR=
0.2 UBRR=
3.7 UBRR=
7.5 UBRR=
7.8 UBRR=
7.8 UBRR=
7.8 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
0.0 UBRR=
6.7 UBRR=
0.0 UBRR=
R/W
2.4576 MHz %Error
11.059 MHz %Error
2
0
4.608 MHz %Error
R/W
1
0
119
287
143
63
31
15
10
59
29
19
14
71
47
35
23
17
11
7
4
3
2
1
0
9
7
4
3
2
8
5
LSB
R/W
12.5
25.0
20.0
-
0
0
0.0
0.0
0.0
3.1
0.0
6.3
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
6.7
0.0
6.7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0945I–AVR–02/07
UBRR