Atmel ATmega32M1 User Manual

202
7647H–AVR–03/12
Atmel ATmega16/32/64/M1/C1
16.12 Examples of CAN Baud Rate Setting
The CAN bus requires very accurate timing especially for high baud rates. It is recommended to
use only an external crystal for CAN operations.
(Refer to “Bit Timing” on page 176 and “Baud Rate” on page 177 for timing description and page
192 to page 194 for “CAN Bit Timing Registers”).
Table 16-2. Examples of CAN Baud Rate Settings for Commonly Frequencies
fCLK
IO
(MHz)
CAN
Rate
(Kbps)
Description Segments Registers
Sampling
Point
TQ
(µs)
Tbit
(TQ)
Tprs
(TQ)
Tph1
(TQ)
Tph2
(TQ)
Tsjw
(TQ) CANBT1 CANBT2 CANBT3
16.000
1000
69 %
(1)
0.0625 16 7 4 4 1 0x00 0x0C 0x36
(2)
75 % 0.125 8 3 2 2 1 0x02 0x04 0x13
500 75 %
0.125 16 7 4 4 1 0x02 0x0C 0x37
0.250 8 3 2 2 1 0x06 0x04 0x13
250 75 %
0.250 16 7 4 4 1 0x06 0x0C 0x37
0.500 8 3 2 2 1 0x0E 0x04 0x13
200 75 %
0.3125 16 7 4 4 1 0x08 0x0C 0x37
0.625 8 3 2 2 1 0x12 0x04 0x13
125 75 %
0.500 16 7 4 4 1 0x0E 0x0C 0x37
1.000 8 3 2 2 1 0x1E 0x04 0x13
100 75 %
0.625 16 7 4 4 1 0x12 0x0C 0x37
1.250 8 3 2 2 1 0x26 0x04 0x13
12.000
1000 67 %
(1)
0.083333 12 5 3 3 1 0x00 0x08 0x24
(2)
x - - - n o d a t a - - -
500 75 %
0.166666 12 5 3 3 1 0x02 0x08 0x25
0.250 8 3 2 2 1 0x04 0x04 0x13
250 75 %
0.250 16 7 4 4 1 0x04 0x0C 0x37
0.500 8 3 2 2 1 0x0A 0x04 0x13
200 75 %
0.250 20 8 6 5 1 0x04 0x0E 0x4B
0.416666 12 5 3 3 1 0x08 0x08 0x25
125 75 %
0.500 16 7 4 4 1 0x0A 0x0C 0x37
1.000 8 3 2 2 1 0x16 0x04 0x13
100 75 %
0.500 20 8 6 5 1 0x0A 0x0E 0x4B
0.833333 12 5 3 3 1 0x12 0x08 0x25

Atmel ATmega32M1 Specifications

General

Brand	Atmel
Model	ATmega32M1
Category	Microcontrollers
Language	English