ATmega88PA Automotive Atmel Corporation, ATmega88PA Automotive Datasheet - Page 192

• Manufacturer Part Number: ATmega88PA Automotive
• Manufacturer: Atmel Corporation

192
Atmel ATmega48PA/88PA/168PA [Preliminary]
The following equations can be used to calculate the ratio of the incoming data rate and inter-
nal receiver baud rate.
D
S
S
S
R
Table 20-2 on page 192
error that can be tolerated. Note that Normal Speed mode has higher toleration of baud rate
variations.
Table 20-2.
Table 20-3.
F
M
slow
# (Data+Parity Bit)
# (Data+Parity Bit)
10
10
R
D
D
5
6
7
8
9
5
6
7
8
9
slow
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
S
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. R
be accepted in relation to the receiver baud rate.
Recommended Maximum Receiver Baud Rate Error for Normal Speed Mode
(U2Xn = 0)
Recommended Maximum Receiver Baud Rate Error for Double Speed Mode
(U2Xn = 1)
F
M
=
= 4 for Double Speed mode.
= 5 for Double Speed mode.
------------------------------------------------
S 1
–
D
R
R
+
slow
slow
93.20
94.12
94.81
95.36
95.81
96.17
94.12
94.92
95.52
96.00
96.39
96.70
+
and
D
1
(%)
(%)
Table 20-3 on page 192
S
S
+
S
R
R
F
105.66
104.92
104,35
103.90
103.53
103.23
106.67
105.79
105.11
104.58
104.14
103.78
fast
fast
fast
(%)
(%)
is the ratio of the fastest incoming data rate that can
Max Total Error (%)
Max Total Error (%)
+5.66/–5.88
+4.92/–5.08
+4.35/–4.48
+3.90/–4.00
+3.53/–3.61
+3.23/–3.30
+5.79/–5.88
+5.11/–5.19
+4.58/–4.54
+4.14/–4.19
+3.78/–3.83
+6.67/–6.8
list the maximum receiver baud rate
R
fast
F
= 8 for normal speed and
=
M
--------------------------------------------
= 9 for normal speed and
D
+
D
1
Recommended Max
+
Recommended Max
Receiver Error (%)
Receiver Error (%)
2
S
+
S
±2.5
±2.0
±1.5
±1.5
±1.5
±1.0
±2.5
±2.0
±2.0
±1.5
±1.5
±3.0
S
9223B–AVR–09/11
M