ATMEGA128L-8MC View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
'ATMEGA128L-8MC' PDF : 395 Pages View PDF
ATmega128
Examples of Baud Rate
Setting
For standard crystal and resonator frequencies, the most commonly used baud rates for
asynchronous operation can be generated by using the UBRR settings in Table 82.
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 the error ratings are high, especially for large serial
frames (see “Asynchronous Operational Range” on page 187). The error values are cal-
culated using the following equation:
Error[%]
=
⎛
⎝
B----a----u---d----R----a---t--e---C----l-o--s---e--s---t--M----a---t-c--h-
BaudRate
–
1⎠⎞
• 100%
Table 82. Examples of UBRR Settings for Commonly Used Oscillator Frequencies
Baud
Rate
(bps)
fosc = 1.0000 MHz
U2X = 0
U2X = 1
UBRR Error UBRR Error
fosc = 1.8432 MHz
U2X = 0
U2X = 1
UBRR Error UBRR Error
2400
25
0.2%
51
0.2%
47
0.0%
95
0.0%
4800
12
0.2%
25
0.2%
23
0.0%
47
0.0%
9600
6
-7.0%
12
0.2%
11
0.0%
23
0.0%
14.4k
3
8.5%
8
-3.5%
7
0.0%
15
0.0%
19.2k
2
8.5%
6
-7.0%
5
0.0%
11
0.0%
28.8k
1
8.5%
3
8.5%
3
0.0%
7
0.0%
38.4k
1
-18.6%
2
8.5%
2
0.0%
5
0.0%
57.6k
0
8.5%
1
8.5%
1
0.0%
3
0.0%
76.8k
–
–
1
-18.6%
1
-25.0%
2
0.0%
115.2k
–
–
0
8.5%
0
0.0%
1
0.0%
230.4k
–
–
–
–
–
–
0
0.0%
250k
Max (1)
–
–
62.5 kbps
–
–
125 kbps
–
–
115.2 kbps
–
–
230.4 kbps
1.
UBRR = 0, Error = 0.0%
fosc = 2.0000 MHz
U2X = 0
U2X = 1
UBRR Error UBRR Error
51
0.2%
103
0.2%
25
0.2%
51
0.2%
12
0.2%
25
0.2%
8
-3.5%
16
2.1%
6
-7.0%
12
0.2%
3
8.5%
8
-3.5%
2
8.5%
6
-7.0%
1
8.5%
3
8.5%
1
-18.6%
2
8.5%
0
8.5%
1
8.5%
–
–
–
–
–
–
0
0.0%
125 kbps
250 kbps
2467O–AVR–10/06
195
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