CRC Error in CAN FD Frames
Receiver of CAN FD frame shall accept two recessive bits as ACK. If receiver of CAN FD frame detect CRC error it shall signal it at first bit of EOF. This means that during waiting it accepts CRC Delim + 2 ACK bits + ACK delim. Therefore it shall start transmission of error frame 4 bits after the end of CRC field.
Currently CTU CAN FD start transmission of Error flag after 3 bits only! This is bug and it shall be fixed.