ATMEGA169 ATMEL [ATMEL Corporation], ATMEGA169 Datasheet - Page 175

• Manufacturer Part Number: ATMEGA169
• Description: 8-bit Microcontroller with 16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Examples of Baud Rate
Setting
Table 79. Examples of UBRR Settings for Commonly Used Oscillator Frequencies
1.
2514P–AVR–07/06
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)
UBRR = 0, Error = 0.0%
UBRR
25
12
6
3
2
1
1
0
–
–
–
–
62.5 kbps
U2X = 0
f
Error
-18.6%
osc
-7.0%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
–
–
–
–
= 1.0000 MHz
UBRR
51
25
12
8
6
3
2
1
1
0
–
–
125 kbps
U2X = 1
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 79.
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 167). The error values are cal-
culated using the following equation:
Error
-18.6%
-3.5%
-7.0%
0.2%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
–
–
UBRR
47
23
11
7
5
3
2
1
0
–
–
1
115.2 kbps
U2X = 0
Error[%]
f
Error
-25.0%
osc
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
–
–
= 1.8432 MHz
=
UBRR
⎛
⎝
BaudRate
------------------------------------------------------- - 1
95
47
23
15
11
7
5
3
2
1
0
–
230.4 kbps
U2X = 1
BaudRate
Error
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
Closest Match
–
UBRR
51
25
12
–
8
6
3
2
1
1
0
–
–
125 kbps
U2X = 0
⎞
⎠
•
100%
f
Error
ATmega169/V
-18.6%
osc
-3.5%
-7.0%
0.2%
0.2%
0.2%
8.5%
8.5%
8.5%
8.5%
–
–
= 2.0000 MHz
UBRR
103
51
25
16
12
8
6
3
2
1
–
0
250 kbps
U2X = 1
Error
-3.5%
-7.0%
0.2%
0.2%
0.2%
2.1%
0.2%
8.5%
8.5%
8.5%
0.0%
–
175