Development of a new calibration and monitoring system for in-vehicle electronic control units based on controller area network calibration protocol

Abstract

An interactive user-friendly calibration and monitoring system is critical for the development of electronic control units (ECU). In this study, a controller area network (CAN) driver, CAN calibration protocol (CCP) driver, monitoring program, and calibration program in the ECU were designed with the assembly language. The inquiry mode was used in monitoring the program and the interrupt mode was used in the calibration program, which ensured the real-time, simultaneous communication and interruption for the main control program. Mirror memory and the random access memory (RAM) calibration technique were used to reduce the write and read accesses to ECU, and, with the mapping of calibration RAM, calibration parameters could be changed online and used instantly. An efficient database management was used to achieve an accurate dynamic link between PC and ECU. The present system provides reliable, accurate, and quick CAN communication between ECU and PC, with a baud rate up to 500K bit/s. It also provides a friendly, compatible, and flexible calibration interface, and the functions of online calibration and real-time monitoring. This system has been used successfully in high-pressure, common rail, electronically controlled diesel engines and pure electrical vehicles (after a small modification).