MEGA128CAN Datasheet, PDF (260/413 Pages) ATMEL Corporation – Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER

Examples of CAN
Baud Rate Setting
The CAN bus requires very accurate timing especially for high baud rates. It is recom-
mended to use only an external crystal for CAN operations.
(Refer to “Bit Timing” on page 235 for timing description and page 251 to page 252 for
“CAN Bit Timing Registers”).
Table 96. Examples of CAN Baud Rate Settings for Commonly Frequencies
fclk_io
(MHz)
CAN
Baud
Rate
(Kbps)
Description
Sampling
TQ
Point
(µs)
Tbit
(TQ)
Tprs
(TQ)
Segments
Tph1
(TQ)
Tph2
(TQ)
Tsjw
(TQ)
Registers
CANBT1 CANBT2 CANBT3
0.0625
16
7
4
4
1
0x00
0x0C
0x37
1000
75 %
0.125
8
3
2
2
1
0x02
0x04
0x13
0.125
16
7
4
4
1
0x02
0x0C
0x37
500
75 %
0.250
8
3
2
2
1
0x06
0x04
0x13
0.250
16
7
4
250
75 %
0.500
8
3
2
16.000
0.3125
16
7
4
200
75 %
0.625
8
3
2
4
1
0x06
0x0C
0x37
2
1
0x0E
0x04
0x13
4
1
0x08
0x0C
0x37
2
1
0x12
0x04
0x13
0.500
16
7
4
4
1
0x0E
0x0C
0x37
125
75 %
1.000
8
3
2
2
1
0x1E
0x04
0x13
0.625
16
7
4
4
1
0x12
0x0C
0x37
100
75 %
1.350
8
3
2
2
1
0x26
0x04
0x13
0.083333 12
5
3
1000
75 %
x
3
1
0x00
- - - no data- - -
0x08
0x25
0.166666 12
5
3
3
1
0x02
0x08
0x25
500
75 %
0.250
8
3
2
2
1
0x04
0x04
0x13
0.250
16
7
4
4
1
0x04
0x0C
0x37
250
75 %
0.500
8
3
2
2
1
0x0A
0x04
0x13
12.000
0.250
20
8
6
5
1
0x04
0x0E
0x4B
200
75 %
0.416666 12
5
3
3
1
0x08
0x08
0x25
0.500
16
7
4
4
1
0x0A
0x0C
0x37
125
75 %
1.000
8
3
2
2
1
0x16
0x04
0x13
0.500
20
8
6
5
1
0x0A
0x0E
0x4B
100
75 %
0.833333 12
5
3
3
1
0x12
0x08
0x25
260 AT90CAN128
4250E–CAN–12/04