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Ever increasing bandwidth requirements in automotive networks impede the applicabilityof CAN due to its bit rate limitation to 1 MBit/s. To close the gap between CANand other protocols, we improve CAN in two ways: (i) support of bit rates > 1 MBit/sand (ii) support of payloads > 8 byte per frame. We achieve this with a new frame formatwhere we can switch inside the frame to a faster bit rate for (i) and use a differentdata length coding for (ii). This new protocol is called “CAN with Flexible Data-Rate”or CAN FD. CAN FD protocol controllers are also able to perform standard CAN communication.This allows to use CAN FD in specific operation modes, e.g. softwaredownloadat end-of-line programming, while other controllers that do not supportCAN FD are kept in standby.This paper presents the CAN FD frame format with additional bits in the control field toenable the new options and the new CRC sequence to secure longer frames with thesame Hamming distance as in the existing CAN protocol. The configuration optionsfor the two bit rates are explained in detail. We provide measurements of the upperlimits for the bit rate, using the first hardware implementation of a CAN FD protocolcontroller and standard CAN transceivers.