The Design Of CAN Calibration System Based On ASAM Standard

With the progress and rapid development of the society, the requirement of the automobile performance also gradually improves, number of electronic control unit(ECU) used in the car is increasing and the function of the ECU is more and more complex. The control parameters in ECU affect the whole performance of the ECU, and the calibration system can modify the control parameters and observe the parameters that be affected. The calibration system is the efficacious tool for calibration operators to optimize the ECU, and standardization and universal calibration system can shorten the development cycle of electronic control units,reduce costs and play a multiplier effect.In this paper, a universal calibration system is developed based on the ASAM standard and the CCP protocol. The system consists of an adapter connecting ECU and PC and the calibration software platform working on the PC. In this paper, the work is as follows:On the basis of CAN and USB communication, the adapter is designed to transfer the data between CAN and USB. The design of adapter includes two parts: hardware and software. Hardware circuit which is powered by USB uses Freescale's 16-bit microcontroller MC9S12P64 as the core controller and consists of the core control circuit, the CAN communication circuit and the USB communication circuit. Software, using C language and based on Code Warrior platform, consists of CAN communication module, USB communication module and data processing module.On the basis of ASAM standard and CCP communication, using the C++ language to designed the calibration software platform. Calibration software platform uses modular idea to design and the paper focuses on designing system manage module, session establishment module, measurement module, calibration module and FLASH programming module. The manage module realizes the configuration and management of the calibration project, the session establishment module realizes the logic connection with CCP, the measurement module realizes the two communication mode Polling and DAQ, the calibration module realizes the calibration based on RAM and ROM, the FLASH programming module realizes the function of downloading program.After the design is finished, a number of test trials are completed for the basic functions and performance of the calibration system. The target ECU which uses MC9 S12 DG256 microcontroller as main chip and supports DAQ is adopted. With the functional experiments of measurement by Polling and DAQ modes, calibration and FLASH programming and the performance experiment of calibration, the result verifies the correctness and reliability of the calibration system developed and testifies the real-time performance which can meet the needs of the calibration work.