
176
2570N–AVR–05/11
ATmega325/3250/645/6450
20.10 Examples of Baud Rate Setting
For standard crystal and resonator frequencies, the most commonly used baud rates for asyn-
chronous operation can be generated by using the UBRR settings in
Table 20-4. UBRR values
which yield an actual baud rate differing less than 0.5% from the target baud rate, are bold in the
table. Higher error ratings are acceptable, but the Receiver will have less noise resistance when
Error[%]
BaudRate
Closest Match
BaudRate
--------------------------------------------------------
1
–
100%
=
Table 20-4.
Examples of UBRR Settings for Commonly Used Oscillator Frequencies
Baud
Rate
(bps)
fosc = 1.0000 MHz
fosc = 1.8432 MHz
fosc = 2.0000 MHz
U2Xn = 0U2Xn = 1
U2Xn = 0U2Xn = 1U2Xn = 0U2Xn = 1
UBRR
Error
UBRR
Error
UBRR
Error
UBRR
Error
UBRR
Error
UBRR
Error
2400
25
0.2%
51
0.2%
47
0.0%
95
0.0%
51
0.2%
103
0.2%
4800
12
0.2%
25
0.2%
23
0.0%
47
0.0%
25
0.2%
51
0.2%
9600
6
-7.0%
12
0.2%
11
0.0%
23
0.0%
12
0.2%
25
0.2%
14.4k
3
8.5%
8
-3.5%
70.0%
15
0.0%
8
-3.5%
16
2.1%
19.2k
2
8.5%
6
-7.0%
50.0%
11
0.0%
6
-7.0%
12
0.2%
28.8k1
8.5%
3
8.5%
3
0.0%
7
0.0%
3
8.5%
8
-3.5%
38.4k
1
-18.6%
2
8.5%
2
0.0%
5
0.0%
2
8.5%
6
-7.0%
57.6k
0
8.5%
1
8.5%
1
0.0%
3
0.0%
1
8.5%
3
8.5%
76.8k–
–
1
-18.6%
1
-25.0%
20.0%
1-18.6%
2
8.5%
115.2k
–
0
8.5%
0
0.0%
1
0.0%
0
8.5%
1
8.5%
230.4k
–
00.0%
–––
–
250k
–
–––
––0
0.0%
Max. (1)
62.5 kbps
125 kbps
115.2 kbps
230.4 kbps
125 kbps
250 kbps
1.
UBRR = 0, Error = 0.0%