Rapid Prototyping with the Controller Area Network (CAN)

Rapid Control Prototyping (RCP) tools are becoming an essential part of the development process of modern automotive control strategies. The interface between the RCP real-time hardware and the existing electronic control unit (ECU) can be established via Controller Area Network (CAN). In a typical production ECU, the limited availability of unused message objects and the rate of data transfer on the CAN bus are limiting factors which influence the mechanism used for communication between the ECU and the RCP system. This document outlines the details involved in a CAN-based selective bypass approach. A data transfer mechanism is proposed which makes use of only two message objects to establish communication. The introduced time delays and the synchronization of the time driven main tasks are discussed. The proposed mechanism is validated through engine testing and the implementation details are described as well. A standard realization of the proposed mechanism is presented based on the CAN Calibration Protocol (CCP) standard. The CAN-based approach to RCP is shown to be a viable alternative to a Dual Port RAM (DPRAM)-based approach, especially in light of the fact that the hardware flexibility is maintained when the original ECU is being upgraded.