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I am trying to figure out a checksum algorithm. D1 to D6 is data, D7 is a counter obviously and byte 8 must be a CRC, but I didnt have any idea on how to build it. Tried to check if it fits any standard, but no clue yet. Would be awesome if anyone had an idea :) 

    D1  D2  D3  D4  D5  D6  D7  D8
    20  0E  20  00  04  FF  F0  1F
    20  0E  20  00  04  FF  00  60
    20  0E  20  00  04  FF  10  AD
    20  0E  20  00  04  FF  20  E7
    20  0E  20  00  04  FF  30  2A
    20  0E  20  00  04  FF  40  73
    20  0E  20  00  04  FF  50  BE
    20  0E  20  00  04  FF  60  F4
    20  0E  20  00  04  FF  70  39
    20  0E  20  00  04  FF  80  46
    20  0E  20  00  04  FF  90  8B
    20  0D  20  00  04  FF  A0  0B
    20  0D  20  00  04  FF  B0  C6
    20  0D  1F  FF  04  FF  C0  6A
    20  0D  1F  FF  04  FF  D0  A7
    20  0D  1F  FE  04  FF  E0  70
    20  0C  1F  FD  04  FF  F0  41
    20  0C  1F  FD  04  FF  00  3E
    20  0C  1F  FC  04  FF  10  6E
    20  0B  1F  FB  04  FF  20  1F
    20  0B  1F  FB  04  FF  30  D2
    20  0B  1F  FB  04  FF  40  8B
    20  0A  1F  FA  04  FF  50  9D
    20  0A  1F  FA  04  FF  60  D7
    20  0A  1F  F9  04  FF  70  A0
    20  09  1F  F9  04  FF  80  15
    20  09  1F  F9  04  FF  90  D8
    20  09  1F  FA  04  FF  A0  28
    20  08  1F  F9  04  FF  B0  19
    20  08  1F  FA  04  FF  C0  FA
    20  08  1F  F9  04  FF  D0  8D
    20  07  1F  F8  04  FF  E0  9F
    20  07  1F  F8  04  FF  F0  52
    20  06  1F  F8  04  FF  00  6B
    20  05  1F  F7  04  FF  10  04
    20  05  1F  F7  04  FF  20  4E
    20  04  1F  F6  04  FF  30  58
    20  03  1F  F5  04  FF  40  74
    20  03  1F  F5  04  FF  50  B9
    20  03  1F  F5  04  FF  60  F3
    20  02  1F  F5  04  FF  70  78
    20  02  1F  F6  04  FF  80  BD
    20  02  1F  F7  04  FF  90  ED
    20  02  1F  F8  04  FF  A0  CF
    20  02  1F  F9  04  FF  B0  9F
    20  02  1F  FB  04  FF  C0  E1
    20  02  1F  FC  04  FF  D0  D8
    20  02  1F  FD  04  FF  E0  0F
    20  02  1F  FE  04  FF  F0  78
    20  02  1F  FF  04  FF  00  9A
    20  02  1F  FF  04  FF  10  57
    20  02  20  00  04  FF  20  E8
    20  02  20  00  04  FF  30  25
    20  02  20  00  04  FF  40  7C
    20  02  20  00  04  FF  50  B1
    20  02  20  00  04  FF  60  FB
    20  02  20  00  04  FF  70  36
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    Ok, lets start from scratch! How did you capture this dump? Did you use the cantools sniffer for that?
    – perror
    Jun 28, 2018 at 15:09

1 Answer 1

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As can be demonstrated by this page:

  • CRC width: CRC-8
  • CRC parametrization: Predefined, CRC8_SAE_J1850 (Polynomial: 0x1d, Initial value: 0xff, Final xor: 0xff)
  • CRC Input Data: Bytes, D1-D7
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