Bit Rates

The Can In Automation (CiA) workgroup recommends the following speeds and sample moments for the CAN bus (assuming a CAN controller with a 16 MHz clock):

Bit Rate	Bit Time	Time quanta per bit	Time quantum length tq	Location of sample point
1 Mbit/s	1 µs	8	125 ns	6 tq (750 ns)
800 kbits/s (unused in 6xxx series)	1.25 µs	10	125 ns	8 tq (1 µs)
500 kbit/s	2 µs	16	125 ns	14 tq (1.75 µs)
250 kbit/s	4 µs	16	250 ns	14 tq (3.5 µs)
125 kbit/s	8 µs	16	500 ns	14 tq (7 µs)
50 kbit/s	20 µs	16	1.25 µs	14 tq (17.5 µs)
20 kbit/s	50 µs	16	3.125 µs	14 tq (43.75 µs)
10 kbit/s	100 µs	16	6.25 µs	14 tq (87.5 µs)

 

The CAN controller in the 6xxx (except 6172 and 6280) series (82C200 or SJA1000) is clocked with 10 MHz (that is why 800 kbits/s cannot be implemented), this reverts to the following speeds and sample moments:

Bit Rate	Bit Time	Time quanta per bit	Time quantum length tq	Location of sample point
1 Mbit/s	1 µs	5	200 ns	3 tq (600 ns)
500 kbit/s	2 µs	10	200 ns	8 tq (1.6 µs)
250 kbit/s	4 µs	10	400 ns	8 tq (3.2 µs)
125 kbit/s	8 µs	10	800 ns	8 tq (6.4 µs)
50 kbit/s	20 µs	10	2 µs	8 tq (16 µs)
20 kbit/s	50 µs	10	5 µs	8 tq (40 µs)
10 kbit/s	100 µs	10	10 µs	8 tq (80 µs)