| With the degree of electric vehicle’s electrization,intellectualization,networking deepening,the electric vehicle’s power,safety and environment protection have been greatly elevated,and the number of ECU(Electronic Control Unit)is increasing.Known from the practice that ECU’s software needs upgrading to repair bugs and add features,while ECU with large number must be encapsulated in the mechanical enclosure and fixed in the vehicle body.Therefore,traditional detaching method updating ECU will not only cause electrostatic damage to them,but also waste massive labor and material,which leads to extra cost,delays the time to market and even restricts manufacture’s industrialization of electric vehicle.Considering that foreign commercial software is expensive and blocks technical details,the paper investigates the production line’s ECU upgrading demand of domestic manufacture,and relying on some vehicle,develops a set of ECU online upgrading BootLoader system,which has been commercially utilized.This system enables ECU’s main controller to upgrade ECU software using the car body’s existed communication network,without need to remove the cover,keep the debugging interface,and add any hardware.Based on Windows reinstall process,the paper improves the general embedded BootLoader to Three-stage one,adapted to vehicle’s ECU.Three-stage is reflected as follows: firstly,Back-door module(backdoor program,used in User-Application Upgrade process)or Recovery module(recovery program,used in Recovery Upgrade process)responses to upgrading request,then loads Flash-kernel(kernel of Flash)module into RAM(random access memory),which at last takes charge of upgrading job.Three-stage concept makes Bootloader’s process into stage,function into progressiveness,self-upgrading into simplicity,takes full advantage of RAM’s disappearing without power and executing with high rate,thus ensures overall speed and vehicle’s runtime safety.According to the actual need,MFC is used to develop PC side software with compact interface and easy operation,of which incremental updating component implements the extraction of delta code between old and new imaginary file.It decreases duplicated data transmission;and file processing and parsing component implements PC side’s preprocessing on imaginary file,avoiding ECU’s invalid data handling in the host program.Back-door module is integrated with application program,responding upgrading request at any time;Flash-kernel module locates in PC side,loaded into ECU on request;Recovery module is firmware in ECU,identifying and repairing damaged application.All carry BootLoader self-defined protocol short of “BTL communicating protocol”.After completion,firstly,build platform in the laboratory to test by component,then simulate the real vehicle environment to carry on system test,at last conduct repeated upgrading verification in the real vehicle on the whole system.The experiment result shows,ECU online upgrading BootLoader system designed by the paper can meet the index of time(For HEX file with 221 KB,the average time consumed is 59s),stability and security,which reduces cost and improves the vehicle manufacturer’s production line efficiency. |
