Datasheet

165
2503Q–AVR–02/11
ATmega32(L)
Examples of Baud
Rate Setting
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 68. 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 155). The error values are calculated using the following equation:
Error[%]
BaudRate
Closest Match
BaudRate
-------------------------------------------------------- 1–
⎝⎠
⎛⎞
100%•=
Table 68. Examples of UBRR Settings for Commonly Used Oscillator Frequencies
Baud
Rate
(bps)
f
osc
= 1.0000MHz f
osc
= 1.8432MHz f
osc
= 2.0000MHz
U2X = 0 U2X = 1 U2X = 0 U2X = 1 U2X = 0 U2X = 1
UBRR Error UBRR Error UBRR Error UBRR Error UBRR Error UBRR Error
2400 250.2%510.2%470.0%950.0%510.2%1030.2%
4800 120.2%250.2%230.0%470.0%250.2%510.2%
9600 6 -7.0% 12 0.2% 11 0.0% 23 0.0% 12 0.2% 25 0.2%
14.4k 3 8.5% 8 -3.5% 7 0.0% 15 0.0% 8 -3.5% 16 2.1%
19.2k 2 8.5% 6 -7.0% 5 0.0% 11 0.0% 6 -7.0% 12 0.2%
28.8k 1 8.5% 3 8.5% 3 0.0% 7 0.0% 3 8.5% 8 -3.5%
38.4k 1 -18.6% 2 8.5% 2 0.0% 5 0.0% 2 8.5% 6 -7.0%
57.6k 0 8.5% 1 8.5% 1 0.0% 3 0.0% 1 8.5% 3 8.5%
76.8k – – 1 -18.6% 1 -25.0% 2 0.0% 1 -18.6% 2 8.5%
115.2k – – 0 8.5% 0 0.0% 1 0.0% 0 8.5% 1 8.5%
230.4k––––––00.0%––––
250k––––––––––00.0%
Max
(1)
62.5 Kbps 125 Kbps 115.2 Kbps 230.4 Kbps 125 Kbps 250 Kbps
1. UBRR = 0, Error = 0.0%