CAN CC to CAN FD protocol conversion

Hongke (China) is a company providing automotive technology solutions and acting as a distributor of Peak and other CiA members, for example, in China, Japan, Korea, and Singapore.

In-vehicle networks are used to transmit data and control information in vehicle electronic systems. They allow different electronic control units (ECUs) in the vehicle to communicate with each other and coordinate the operation of each system to achieve functional integration and cooperative work. In the vehicle, multiple communication networks coexist. Additionally to the CAN CC (classic) networks, the application range of CAN FD is fast expanding in the recent years. To connect devices or modules using different communication interfaces, protocol conversion is required.

CAN CC to CAN FD protocol conversion

When adding a CAN FD node to a CAN CC network, the CAN FD node has to communicate with other CAN CC nodes via CAN CC frames. The CAN CC network participants can not recognize the CAN FD frames from a CAN FD node. Thus, sending a CAN FD frame in a CAN CC network would result in communication errors. Similarly, when a CAN CC node is added to a CAN FD network, it is unable to communicate with other CAN FD nodes, and a bus error occurs. Therefore, it is necessary to add a gateway between CAN CC and CAN FD networks to convert the exchanged frames and ensure communication. Such gateways often have multiple CAN CC and CAN FD interfaces and are programmable.

Firstly, it is required to define the bit-rate of the gateway, including the two bit rates for the arbitration phase and the data phase in CAN FD networks. Secondly, the specific frame structure needs to be modified in order to create a complete structure of the data frame, focusing on modifying the frame type, DLC (data length code), and the specific data of the message.

Application of gateways in automotive industry

Hongke already offers mature CAN CC to CAN FD protocol conversion solutions using PCAN-Router FD and PCAN-Router Pro FD gateways from Peak System. One of the classic application scenarios is the OEM (original equipment manufacturer) optimization of the test bench.

In ECU testing, engineers build different test benches for different car parts. In the past, test benches supporting CAN CC communication have been built. Nowadays, the ECU testing is expanding towards CAN FD and CAN XL, so it is necessary to optimize the test benches.

The purpose of the test bench modification is to forward CAN FD frames from ECUs to the CAN CC devices in the bench (and vice versa). The mentioned gateways can establish a CAN CC to CAN FD communication between the test bench and the ECU. The CAN FD frames from the ECU can be transmitted through the gateway in real time and output to the test bench as CAN CC frames. This enables to optimize the bench test solutions for different CAN-based networks helping customers to reduce time, manpower cost, and engineering complexity of the protocol conversion, informs Hongke.

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