Atmel AVR XMEGA AU series User Manual

303
8331B–AVR–03/12
Atmel AVR XMEGA AU
Table 23-3 and Table 23-4 on page 303 list the maximum receiver baud rate error that can be
tolerated. Normal speed mode has higher tolerance of baud rate variations.
The recommendations for the maximum receiver baud rate error assume that the receiver and
transmitter equally divide the maximum total error.
D Sum of character size and parity size (D = 5 to 10 bits).
S Samples per bit. S = 16 for normal speed mode and S = 8 for double speed mode.
S
F
First sample number used for majority voting. S
F
= 8 for normal speed mode and S
F
= 4 for dou-
ble speed mode.
S
M
Middle sample number used for majority voting. S
M
= 9 for normal speed mode and S
M
= 5 for
double speed mode.
R
slow
The ratio of the slowest incoming data rate that can be accepted in relation to the receiver baud
rate.
R
fast
The ratio of the fastest incoming data rate that can be accepted in relation to the receiver baud
rate.
Table 23-3. Recommended maximum receiver baud rate error for normal speed mode
D
#(Data + Parity Bit) R
slow
[%] R
fast
[%] Max Total Error [%]
Recommended Max
Receiver Error [%]
5 93.20 106.67 +6.67/-6.80 ± 3.0
6 94.12 105.79 +5.79/-5.88 ± 2.5
7 94.81 105.11 +5.11/-5.19 ± 2.0
8 95.36 104.58 +4.58/-4.54 ± 2.0
9 95.81 104.14 +4.14/-4.19 ± 1.5
10 96.17 103.78 +3.78/-3.83 ± 1.5
Table 23-4. Recommended maximum receiver baud rate error for double speed mode
D
#(Data + Parity Bit) R
slow
[%] R
fast
[%] Max Total Error [%]
Recommended Max
Receiver Error [%]
5 94.12 105.66 +5.66/-5.88 ± 2.5
6 94.92 104.92 +4.92/-5.08 ± 2.0
7 95.52 104.35 +4.35/-4.48 ± 1.5
8 96.00 103.90 +3.90/-4.00 ± 1.5
9 96.39 103.53 +3.53/-3.61 ± 1.5
10 96.70 103.23 +3.23/-3.30 ± 1.0
R
slow
D 1+()S
S 1– DS⋅ S
F
++
------------------------------------------ -=
R
fast
D 2+()S
D 1+()SS
M
+
-----------------------------------=

Atmel AVR XMEGA AU series Specifications

General

Brand	Atmel
Model	AVR XMEGA AU series
Category	Microcontrollers
Language	English