Table 17-9. Examples of UBRRn Settings for Commonly Used Oscillator Frequencies
fosc = 1.0000 MHz fosc = 1.8432 MHz
U2Xn = 0 U2Xn = 1 U2Xn = 0 U2Xn = 1
fosc = 2.0000 MHz
U2Xn = 0 U2Xn = 1
Baud
Rate
(bps)
UBRR
n
UBRR
n
UBRR
n
UBRR
n
UBRR
n
UBRR
n
Error
0.2ꢀ
0.2ꢀ
-7.0ꢀ
8.5ꢀ
8.5ꢀ
8.5ꢀ
-18.6ꢀ
8.5ꢀ
–
Error
0.2ꢀ
0.2ꢀ
0.2ꢀ
-3.5ꢀ
-7.0ꢀ
8.5ꢀ
8.5ꢀ
8.5ꢀ
-18.6ꢀ
8.5ꢀ
–
Error
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
-25.0ꢀ
0.0ꢀ
–
Error
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
0.0ꢀ
–
Error
0.2ꢀ
0.2ꢀ
0.2ꢀ
-3.5ꢀ
-7.0ꢀ
8.5ꢀ
8.5ꢀ
8.5ꢀ
-18.6ꢀ
8.5ꢀ
–
Error
0.2ꢀ
0.2ꢀ
0.2ꢀ
2.1ꢀ
0.2ꢀ
-3.5ꢀ
-7.0ꢀ
8.5ꢀ
8.5ꢀ
8.5ꢀ
–
2400
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
4800
9600
14.4k
19.2k
28.8k
38.4k
57.6k
76.8k
115.2k
230.4k
250k
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
–
–
–
–
–
–
–
–
–
–
–
0
0.0ꢀ
Max.(1)
62.5 kbps
125 kbps
115.2 kbps
230.4 kbps
125 kbps
250 kbps
Note:
1. UBRRn = 0, Error = 0.0ꢀ
192
ATmega48/88/168
2545E–AVR–02/05
MICROCHIP [ MICROCHIP ]
