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
Description
Segments
Registers
CAN
Rate
(Kbps)
f
CLK
(MHz)
Sampling
Point
TQ
(µs)
Tbit
(TQ)
Tprs
(TQ)
Tph1
Tph2
Tsjw
(TQ)
IO
(TQ)
(TQ)
CANBT1 CANBT2
CANBT3
0x36 (2)
0x13
69 % (1)
0.0625
0.125
16
8
7
3
7
3
7
3
7
3
7
3
7
3
5
4
2
4
2
4
2
4
2
4
2
4
2
3
4
2
4
2
4
2
4
2
4
2
4
2
3
1
1
1
1
1
1
1
1
1
1
1
1
1
0x00
0x02
0x02
0x06
0x06
0x0E
0x08
0x12
0x0E
0x1E
0x12
0x26
0x00
0x0C
0x04
0x0C
0x04
0x0C
0x04
0x0C
0x04
0x0C
0x04
0x0C
0x04
0x08
1000
500
250
200
125
100
1000
500
250
200
125
100
75 %
0.125
16
8
0x37
75 %
75 %
75 %
75 %
75 %
67 % (1)
75 %
75 %
75 %
75 %
75 %
0.250
0x13
0.250
16
8
0x37
0.500
0x13
16.000
0.3125
0.625
16
8
0x37
0x13
0.500
16
8
0x37
1.000
0x13
0.625
16
8
0x37
1.250
0x13
0.083333
12
x
0x24 (2)
- - - n o d a t a - - -
0.166666
0.250
12
8
5
3
7
3
8
5
7
3
8
5
3
2
4
2
6
3
4
2
6
3
3
2
4
2
5
3
4
2
5
3
1
1
1
1
1
1
1
1
1
1
0x02
0x04
0x04
0x0A
0x04
0x08
0x0A
0x16
0x0A
0x12
0x08
0x04
0x0C
0x04
0x0E
0x08
0x0C
0x04
0x0E
0x08
0x25
0x13
0x37
0x13
0x4B
0x25
0x37
0x13
0x4B
0x25
0.250
16
8
0.500
12.000
0.250
20
12
16
8
0.416666
0.500
1.000
0.500
20
12
0.833333
202
ATmega16/32/64/M1/C1
7647F–AVR–04/09
ATMEL [ ATMEL ]
