peterperkins
100 W
- Joined
- Jun 6, 2008
- Messages
- 196
I'm working on a microcontroller project that might eventually get transferred to a micromite but I am struggling to understand a CANBUS crc and security type code formulae.
I sampled some repeating CANBUS data from a working BMS system.
I'm wondering how the two bytes at the end of the packet are generated.
I assume the last is a CRC and the penultimate one some sort of security check as it may not be data related.
Any leads would be appreciated. Sadly polynomials is not my strong point.
ID,D1,D2,D3,D4,D5,D6,D7,D8
203,0,0,0,0,0,0,0,9A
203,0,0,0,0,0,0,20,2F
203,0,0,0,0,0,0,1D,7E
203,0,0,0,0,0,0,0,8B
203,0,0,0,0,0,0,20,10
203,0,0,0,0,0,0,1D,6F
203,0,0,0,0,0,0,0,B8
203,0,0,0,0,0,0,20,1
203,0,0,0,0,0,0,1D,50
203,0,0,0,0,0,0,0,A9
203,0,0,0,0,0,0,20,3E
203,0,0,0,0,0,0,1D,41
203,0,0,0,0,0,0,0,9A
203,0,0,0,0,0,0,20,2F
203,0,0,0,0,0,0,1D,7E
203,0,0,0,0,0,0,0,8B
203,0,0,0,0,0,0,20,10
203,0,0,0,0,0,0,1D,6F
203,0,0,0,0,0,0,0,B8
203,0,0,0,0,0,0,20,1
203,0,0,0,0,0,0,1D,50
203,0,0,0,0,0,0,0,A9
203,0,0,0,0,0,0,20,3E
203,0,0,0,0,0,0,1D,41
203,0,0,0,0,0,0,0,9A
203,0,0,0,0,0,0,20,2F
203,0,0,0,0,0,0,1D,7E
203,0,0,0,0,0,0,0,8B
203,0,0,0,0,0,0,20,10
203,0,0,0,0,0,0,1D,6F
203,0,0,0,0,0,0,0,B8
203,0,0,0,0,0,0,20,1
203,0,0,0,0,0,0,1D,50
203,0,0,0,0,0,0,0,A9
203,0,0,0,0,0,0,20,3E
203,0,0,0,0,0,0,1D,41
203,0,0,0,0,0,0,0,9A
203,0,0,0,0,0,0,20,2F
203,0,0,0,0,0,0,1D,7E
203,0,0,0,0,0,0,0,8B
203,0,0,0,0,0,0,20,10
and a bit more with some data.
203,24,62,46,24,72,47,20,3C
203,24,92,46,24,72,47,2B,4D
203,24,A2,4B,0,0,0,0,99
203,24,62,46,24,72,46,20,2E
203,24,92,46,24,72,46,2B,7B
203,24,92,4D,0,0,0,0,89
203,24,42,44,24,72,44,20,15
203,24,92,44,24,72,4A,2B,6A
203,24,C2,4C,0,0,0,0,B4
203,24,22,42,24,62,3F,20,1
203,24,92,42,24,62,4F,2B,59
203,25,32,4B,0,0,0,0,AE
Grateful for any leads and ideas..
I have done a fair bit of googling and read some excellent articles but the maths is way over my head.
I sampled some repeating CANBUS data from a working BMS system.
I'm wondering how the two bytes at the end of the packet are generated.
I assume the last is a CRC and the penultimate one some sort of security check as it may not be data related.
Any leads would be appreciated. Sadly polynomials is not my strong point.
ID,D1,D2,D3,D4,D5,D6,D7,D8
203,0,0,0,0,0,0,0,9A
203,0,0,0,0,0,0,20,2F
203,0,0,0,0,0,0,1D,7E
203,0,0,0,0,0,0,0,8B
203,0,0,0,0,0,0,20,10
203,0,0,0,0,0,0,1D,6F
203,0,0,0,0,0,0,0,B8
203,0,0,0,0,0,0,20,1
203,0,0,0,0,0,0,1D,50
203,0,0,0,0,0,0,0,A9
203,0,0,0,0,0,0,20,3E
203,0,0,0,0,0,0,1D,41
203,0,0,0,0,0,0,0,9A
203,0,0,0,0,0,0,20,2F
203,0,0,0,0,0,0,1D,7E
203,0,0,0,0,0,0,0,8B
203,0,0,0,0,0,0,20,10
203,0,0,0,0,0,0,1D,6F
203,0,0,0,0,0,0,0,B8
203,0,0,0,0,0,0,20,1
203,0,0,0,0,0,0,1D,50
203,0,0,0,0,0,0,0,A9
203,0,0,0,0,0,0,20,3E
203,0,0,0,0,0,0,1D,41
203,0,0,0,0,0,0,0,9A
203,0,0,0,0,0,0,20,2F
203,0,0,0,0,0,0,1D,7E
203,0,0,0,0,0,0,0,8B
203,0,0,0,0,0,0,20,10
203,0,0,0,0,0,0,1D,6F
203,0,0,0,0,0,0,0,B8
203,0,0,0,0,0,0,20,1
203,0,0,0,0,0,0,1D,50
203,0,0,0,0,0,0,0,A9
203,0,0,0,0,0,0,20,3E
203,0,0,0,0,0,0,1D,41
203,0,0,0,0,0,0,0,9A
203,0,0,0,0,0,0,20,2F
203,0,0,0,0,0,0,1D,7E
203,0,0,0,0,0,0,0,8B
203,0,0,0,0,0,0,20,10
and a bit more with some data.
203,24,62,46,24,72,47,20,3C
203,24,92,46,24,72,47,2B,4D
203,24,A2,4B,0,0,0,0,99
203,24,62,46,24,72,46,20,2E
203,24,92,46,24,72,46,2B,7B
203,24,92,4D,0,0,0,0,89
203,24,42,44,24,72,44,20,15
203,24,92,44,24,72,4A,2B,6A
203,24,C2,4C,0,0,0,0,B4
203,24,22,42,24,62,3F,20,1
203,24,92,42,24,62,4F,2B,59
203,25,32,4B,0,0,0,0,AE
Grateful for any leads and ideas..
I have done a fair bit of googling and read some excellent articles but the maths is way over my head.