Dr. Arthur Mutter from Bosch has written a white paper about the CRC weaknesses in the original CAN FD protocol. The paper describes in detail the technical background and the solutions.
DURING THE STANDARDIZATION PROCESS IN THE ISO, several experts detected some CRC issues in the CAN FD protocol. The responsible ISO Task Force discussed the problems and proposed a solution. The agreed improvements are already part of the ISO 11898-1 document submitted for DIS (Draft International Standard) balloting. Bosch has written a white paper explaining the CRC weaknesses and the solutions developed within the ISO Task Force.
The paper discusses in detail bit-flip faults and faults caused by shortening or lengthening of bit sequences. It includes also exemplary cases demonstrating the CRC issue. In the solution chapter, the stuff-bit counter and the related parity bit are introduced. This paper provides the technical background, why and how the CAN FD frame format has been changed.
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