Developing a robust CAN physical layer implementation for In-Vehicle Networks using the Robust Design Method

CAN is the current In-Vehicle network standard and is a very well known protocol. Even though the protocol is well understood, implementing its physical layer is becoming more and more challenging. Vehicle manufacturers have decided to replace current low speed CAN implementations with high speed CAN solutions. This is a requirement of the increasing bus load. The number of electronic control units increases for individual CAN high speed sub-networks which makes it more challenging to ensure a robust implementation of the targeted network topology. A manual verification of the In-Vehicle network's signal integrity in the early stage of development, where no hardware prototypes are available, is not possible due to its high transient behavior. The only choice to verify prototype topologies is through a model based design flow. A virtual In-Vehicle network implementation allows the early verification of physical layer robustness before any hardware prototypes are built-up. This allows the network developer to discover any possible issues very early and to fix them without changing any hardware implementations. This paper gives an overview of the challenges network developers face when dealing with the physical layer implementation. In addition it shows how to develop a robust implementation through a model based design method, taking into account environmental variations and component tolerances to ensure the system works even under worst case conditions.