ATmega8(L)
Examples of Baud 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 60. UBRR values
Rate Setting
which yield an actual baud rate differing less than 0.5ꢀ from the target baud rate, are bold in the
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 “Asynchronous Operational
Range” on page 144). The error values are calculated using the following equation:
BaudRateClosest Match
Error[ꢀ] = ------------------------------------------------------- – 1 100ꢀ
BaudRate
Table 60. Examples of UBRR Settings for Commonly Used Oscillator Frequencies
fosc = 1.0000MHz fosc = 1.8432MHz
U2X = 0 U2X = 1 U2X = 0 U2X = 1
UBRR UBRR UBRR UBRR
fosc = 2.0000MHz
U2X = 0 U2X = 1
UBRR
Baud
Rate
(bps)
Error
0.2%
0.2%
-7.0ꢀ
8.5ꢀ
8.5ꢀ
8.5ꢀ
-18.6ꢀ
8.5ꢀ
–
Error
0.2%
0.2%
0.2%
-3.5ꢀ
-7.0ꢀ
8.5ꢀ
8.5ꢀ
8.5ꢀ
-18.6ꢀ
8.5ꢀ
–
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
-25.0ꢀ
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%
–
UBRR
Error
0.2%
0.2%
0.2%
-3.5ꢀ
-7.0ꢀ
8.5ꢀ
8.5ꢀ
8.5ꢀ
-18.6ꢀ
8.5ꢀ
-
Error
0.2%
0.2%
0.2%
2.1ꢀ
0.2%
-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
0.0%
Max (1)
62.5kbps
UBRR = 0, Error = 0.0ꢀ
125kbps
115.2kbps
230.4kbps
125kbps
250kbps
1.
153
2486AA–AVR–02/2013
ATMEL [ ATMEL ]
