AT90PWM2B-16SE ATMEL [ATMEL Corporation], AT90PWM2B-16SE Datasheet - Page 199

• Manufacturer Part Number: AT90PWM2B-16SE
• Description: 8-bit Microcontroller with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

18.8.3
4317J–AVR–08/10
Asynchronous Operational Range
The operational range of the Receiver is dependent on the mismatch between the received bit
rate and the internally generated baud rate. If the Transmitter is sending frames at too fast or too
slow bit rates, or the internally generated baud rate of the Receiver does not have a similar (see
Table
bit.
The following equations can be used to calculate the ratio of the incoming data rate and internal
receiver baud rate.
D
S
S
S
R
receiver baud rate.
R
Table 18-2
that Normal Speed mode has higher toleration of baud rate variations.
Table 18-2.
F
M
slow
fast
# (Data+Parity Bit)
is the ratio of the fastest incoming data rate that can be accepted in relation to the
Sum of character size and parity size (D = 5 to 10 bit)
Samples per bit. S = 16 for Normal Speed mode and S = 8 for Double Speed
mode.
First sample number used for majority voting. S
for Double Speed mode.
Middle sample number used for majority voting. S
S
is the ratio of the slowest incoming data rate that can be accepted in relation to the
receiver baud rate.
18-2) base frequency, the Receiver will not be able to synchronize the frames to the start
M
= 5 for Double Speed mode.
10
D
5
6
7
8
9
R
and
slow
Recommended Maximum Receiver Baud Rate Error for Normal Speed Mode
(U2X = 0)
Table 18-3
=
------------------------------------------ -
S 1
–
(
R
D
+
slow
93.20
94.12
94.81
95.36
95.81
96.17
+
D S ⋅
list the maximum receiver baud rate error that can be tolerated. Note
1
(%)
)S
+
S
F
R
106.67
105.79
105.11
104.58
104.14
103.78
fast
(%)
Max Total Error (%)
+5.79/-5.88
+5.11/-5.19
+4.58/-4.54
+4.14/-4.19
+3.78/-3.83
F
+6.67/-6.8
= 8 for normal speed and S
M
AT90PWM2/3/2B/3B
= 9 for normal speed and
R
fast
=
-----------------------------------
(
D
(
+
D
1
+
)S
Recommended Max
2
Receiver Error (%)
)S
+
S
M
± 3.0
± 2.5
± 2.0
± 2.0
± 1.5
± 1.5
F
= 4
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