Research On Design Of In-Vehicle CAN/FLEXRAY Gateway Technology

With the rapid development of the electronic technology and semiconductor technology, electronic products are increasing in the car, which lead a set of standards and a set of subnets in vehicle netowork simultaneously. Gateway is the core of vehicle network to achieve the interaction of information between subnets. Based on the actual project, the paper studys the technology of CAN gateway that achieves the interaction of information between CAN subnets, and CAN-FlexRay gateway that achieves the interaction of information between CAN subnet and FlexRay subnet.In the research of CAN gateway, the function of CAN gateway is divided into six components, the paper studys static low-power technology, message routing technology, timer architecture and receiving and transmitting port structure of which in depth. Based on finite state machine, the static low-power technology of CAN gateway, which reduce battery power consumption, drives all electronic control units in vehicles network into hibernation after the latch. The message routing technology that is based on the reference module of CAN node can quickly complete information mapping and transmission trigger among subnets to reduce routing delay time. Refer to clock frequency and a single list structure, timer architecture can meet the condition of system clock accuracy, and simultaneously reduce run-time of timer. Meanwhile, the receiving and transmitting port structure can avoid the influence on CAN gateway when the bus is high load-carry duty and the influence on the bus in the condition that the gateway should transmit lots of messages in a short time.In the research of CAN-FlexRay gateway, the double buffer structure of the gateway ensures the data integrity when convertingFlexRay data to CAN data. The way of "base address + offset address" can quickly locate date field that is used to the mapping between FlexRay data and CAN data. Meanwhile, the rewrite scheduling algorithm of the gateway is used to overcome the fact the state of transmit buffer is not visible for the appliction when converting CAN data to FlexRay data.Finally, the gateway test system, which consistes of the entity of gateway and bus simulation monitoring tool, is used to verify the validity of the gateway. Experimental results of CAN gateway show that the gateway can quickly realize the interaction of information among CAN subnets in the normal state, and drive to hibernation after latch. Meanwhile, experimental results of CAN-FlexRay gateway show that the gateway can realize the interaction of information between CAN subnet and FlexRay subnet.