197
8271D–AVR–05/11
ATmega48A/PA/88A/PA/168A/PA/328/P
table. Higher error ratings are acceptable, but the Receiver will have less noise resistance when
the error ratings are high, especially for large serial frames (see
). The error values are calculated using the following equation:
Note:
1. UBRRn = 0, Error = 0.0%
Error[%]
BaudRate
Closest Match
BaudRate
--------------------------------------------------
1
–
⎝
⎠
⎛
⎞
100
%
•
=
Examples of UBRRn Settings for Commonly Used Oscillator Frequencies
Baud
Rate
(bps)
f
osc
= 1.0000MHz
f
osc
= 1.8432MHz
f
osc
= 2.0000MHz
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
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%
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%
62.5kbps
125kbps
115.2kbps
230.4kbps
125kbps
250kbps