J1939 message counter & checksum function

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Adrian Barber

• January 30, 2018 19:29

Would it be possible to have a standard funtion that we can select when required, the standard J1939 checksum and message counter as used in the TSC1 SPN 4206 & 4207.

 

The J1939 SAE spec suggest the CRC calculation to be 

^{Checksum = (Byte1 + Byte2 + Byte3 + Byte4 + Byte5 + Byte6 + Byte7 + message counter & 0x0F + message ID low byte + message ID mid low byte + message ID mid high byte + message ID high byte)
Message Checksum = (((Checksum >> 6) & 0x03) + (Checksum >>3) +  Checksum) & 0x07}

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  Boyce S.

  • January 30, 2018 22:40

  Thanks for the suggestion.  Are you referring to a monochrome or color display?

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  Adrian Barber

  • January 31, 2018 06:01

  Both would be nice, but our primary request would be colour. Cheers.

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