Datasheet

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Table 34-3. Asynchronous Receiver Error for 16-fold Oversampling
D
(Data bits+Parity)
R
SLOW
[%] R
FAST
[%] Max. total error [%] Recommended max. Rx error [%]
5 94.12 107.69 +5.88/-7.69 ±2.5
6 94.92 106.67 +5.08/-6.67 ±2.0
7 95.52 105.88 +4.48/-5.88 ±2.0
8 96.00 105.26 +4.00/-5.26 ±2.0
9 96.39 104.76 +3.61/-4.76 ±1.5
10 96.70 104.35 +3.30/-4.35 ±1.5
The following equations calculate the ratio of the incoming data rate and internal receiver baud rate:
SLOW
=
+ 1
1 + +
,
FAST
=
+ 2
+ 1 +
R
SLOW
is the ratio of the slowest incoming data rate that can be accepted in relation to the receiver
baud rate
R
FAST
is the ratio of the fastest incoming data rate that can be accepted in relation to the receiver
baud rate
D is the sum of character size and parity size (D = 5 to 10 bits)
S is the number of samples per bit (S = 16, 8 or 3)
S
F
is the first sample number used for majority voting (S
F
= 7, 3, or 2) when CTRLA.SAMPA=0.
S
M
is the middle sample number used for majority voting (S
M
= 8, 4, or 2) when CTRLA.SAMPA=0.
The recommended maximum Rx Error assumes that the receiver and transmitter equally divide the
maximum total error. Its connection to the SERCOM Receiver error acceptance is depicted in this figure:
Figure 34-5. USART Rx Error Calculation
+
+
Error Max (%)
Error Min (%)
Baud Rate
SERCOM Receiver error acceptance
from RSLOW and RFAST formulas
Baud Generator offset error
depends on BAUD register value
+
Clock source error
Recommended max. Rx Error (%)
The recommendation values in the table above accommodate errors of the clock source and the baud
generator. The following figure gives an example for a baud rate of 3Mbps:
SAM D5x/E5x Family Data Sheet
SERCOM USART - SERCOM Synchronous and Asyn...
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Datasheet
DS60001507E-page 930