
192
7810C–AVR–10/12
Atmel ATmega328P [Preliminary]
19.11 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 UBRRn settings in
Table 19-9. UBRRn
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 resis-
tance when the error ratings are high, especially for large serial frames (see
“AsynchronousNote:
1. UBRRn = 0, Error = 0.0%
Error[%]
BaudRate
Closest Match
BaudRate
--------------------------------------------------------
1
–
100%
=
Table 19-9.
Examples of UBRRn Settings for Commonly Used Oscillator Frequencies
Baud
Rate
(bps)
fosc = 1.0000 MHz
fosc = 1.8432 MHz
fosc = 2.0000 MHz
U2Xn = 0
U2Xn = 1
U2Xn = 0
U2Xn = 1
U2Xn = 0
U2Xn = 1
UBRRn
Error
UBRRn
Error
UBRRn
Error
UBRRn
Error
UBRRn
Error
UBRRn
Error
2400
25
0.2%
51
0.2%
47
0.0%
95
0.0%
51
0.2%
103
0.2%
4800
120.2%250.2%230.0%47
0.0%
250.2%
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%
7
0.0%
15
0.0%
8
-3.5%
16
2.1%
19.2k
2
8.5%
6
-7.0%
5
0.0%
11
0.0%
6
-7.0%
12
0.2%
28.8k
1
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%
2
0.0%
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
–––
–––0
0.0%
–
250k
–––
––––
–
–0
0.0%
62.5 kbps
125 kbps
115.2 kbps
230.4 kbps
125 kbps
250 kbps