Improving compatibility between CAN FD and legacy CAN devices

To overcome the performance limitations of Controller Area Network (CAN), the CAN with Flexible Data-rate (CAN FD) specification has been recently released, which features increased network throughput by combining bit rate overclocking and frame oversizing. CAN FD ensures good backward compatibility with existing applications and higher protocol layers conceived for CAN. Unfortunately, high-performance transmission services shall not be used in networks where also legacy CAN controllers are connected, as doing so raises serious compatibility problems, which in turn undermine system reliability severely and lead to unsafe behavior. In this paper, the above problem is analyzed carefully and a number of solutions are proposed, which carry out a negotiation among CAN nodes so as to improve interoperability between legacy and CAN FD controllers.