ATmega325PA Atmel Corporation, ATmega325PA Datasheet - Page 189

• Manufacturer Part Number: ATmega325PA
• Manufacturer: Atmel Corporation

20.10 Examples of Baud Rate Setting
Table 20-4.
Note:
8285D–AVR–06/11
Baud
Rate
(bps)
2400
4800
9600
14.4k
19.2k
28.8k
38.4k
57.6k
76.8k
115.2k
230.4k
250k
Max.
(1)
1. UBRRn = 0, Error = 0.0%
UBRRn
25
12
6
3
2
1
1
0
–
–
–
–
62.5 kbps
Examples of UBRRn Settings for Commonly Used Oscillator Frequencies
U2Xn = 0
ATmega165A/PA/325A/PA/3250A/PA/645A/P/6450A/P
f
Error
-18.6%
-7.0%
osc
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
–
–
–
–
= 1.0000MHz
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
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
Operational Range” on page
UBRRn
51
25
12
8
6
3
2
1
1
0
–
–
U2Xn = 1
125 kbps
Error
-18.6%
-3.5%
-7.0%
0.2%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
–
–
UBRRn
47
23
11
7
5
3
2
1
1
0
–
–
115.2 kbps
Error[%]
U2Xn = 0
186). The error values are calculated using the following equation:
f
osc
Error
-25.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
=
–
–
= 1.8432MHz
⎛
⎝
BaudRate
------------------------------------------------------- - 1
UBRRn
BaudRate
95
47
23
15
11
230.4 kbps
2
U2Xn = 1
7
5
3
1
0
–
Closest Match
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
–
–
UBRRn
⎞
⎠
•
51
25
12
8
6
3
2
1
1
0
–
–
100%
U2Xn = 0
125 kbps
f
Error
osc
-18.6%
-3.5%
-7.0%
0.2%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
–
–
= 2.0000MHz
Table
UBRRn
”Asynchronous
103
51
25
16
12
20-4. UBRRn
8
6
3
2
1
–
0
U2Xn = 1
250 kbps
Error
-3.5%
-7.0%
0.2%
0.2%
0.2%
2.1%
0.2%
8.5%
8.5%
8.5%
0.0%
–
189