AT90PWM2/3/2B/3B
Table 18-9. Examples of UBRR Settings for Commonly Frequencies
fclkio = 1.0000 MHz
U2X = 0 U2X = 1
UBRR UBRR
fclkio = 1.8432 MHz
U2X = 0 U2X = 1
UBRR UBRR
fclkio = 2.0000 MHz
Baud
Rate
(bps)
U2X = 0
UBRR
U2X = 1
UBRR
Error
0.2%
0.2%
-7.0%
8.5%
8.5%
8.5%
-18.6%
8.5%
–
Error
0.2%
0.2%
0.2%
-3.5%
-7.0%
8.5%
8.5%
8.5%
-18.6%
8.5%
–
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
-25.0%
0.0%
–
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
–
Error
0.2%
0.2%
0.2%
-3.5%
-7.0%
8.5%
8.5%
8.5%
-18.6%
8.5%
–
Error
0.2%
0.2%
0.2%
2.1%
0.2%
-3.5%
-7.0%
8.5%
8.5%
8.5%
–
2400
4800
9600
14.4k
19.2k
28.8k
38.4k
57.6k
76.8k
115.2k
230.4k
250k
25
12
6
51
25
12
8
47
23
11
7
95
47
23
15
11
7
51
25
12
8
103
51
25
16
12
8
3
2
6
5
6
1
3
3
3
1
2
2
5
2
6
0
1
1
3
1
3
–
1
1
2
1
2
–
–
0
0
1
0
1
–
–
–
–
0
–
–
–
–
–
–
–
–
–
–
–
–
–
500k
–
–
–
–
–
–
–
–
–
–
–
–
1M
–
–
–
–
–
–
–
–
–
–
–
–
Max. (1)
62.5 kbps
UBRR = 0, Error = 0.0%
125 kbps
115.2 kbps
230.4 Kbps
125 kpbs
250 kbps
1.
Table 18-10. Examples of UBRR Settings for Commonly Frequencies (Continued)
fclkio = 3.6864 MHz
U2X = 0
fclkio = 4.0000 MHz
U2X = 0
fclkio = 7.3728 MHz
U2X = 0
Baud
Rate
(bps)
U2X = 1
U2X = 1
U2X = 1
UBRR
383
191
95
UBRR
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
-7.8%
UBRR
191
95
47
31
23
15
11
7
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
-7.8%
UBRR
Error
0.2%
0.2%
0.2%
2.1%
0.2%
-3.5%
-7.0%
8.5%
8.5%
8.5%
8.5%
0.0%
UBRR
207
103
51
34
25
16
12
8
Error
0.2%
0.2%
0.2%
-0.8%
0.2%
2.1%
0.2%
-3.5%
-7.0%
8.5%
8.5%
0.0%
UBRR
191
95
47
31
23
15
11
7
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
-7.8%
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
-7.8%
2400
95
47
23
15
11
7
103
51
25
16
12
8
4800
9600
14.4k
19.2k
28.8k
38.4k
57.6k
76.8k
115.2k
230.4k
250k
63
47
31
5
6
23
3
3
15
2
5
2
6
5
11
1
3
1
3
3
7
0
1
0
1
1
3
0
1
0
1
1
3
207
4317J–AVR–08/10
ATMEL [ ATMEL ]
