Design and Implementation of Remote Upgrade System for Vehicle Terminal Based on GPRS

The function of vehicle telematics box(T-BOX) changes with the change of user’s demand. In order to adapt to the new demands and changes with the same terminal at different stages, the telematics box should be able to adjust themselves dynamically or the supplier can remotely upgrade the telematics box. In this paper, a remote upgrade scheme of T-box terminal based on GPRS network is proposed, and the remote upgrade system is designed and implemented. The remote upgrade system adopts passive mode that is once the T-box terminal receives the firmware upgrade command, it will download the latest version firmware from the server and does the MD5 verification. The MD5 algorithm is used to ensure the authenticity and integrity of firmware updates. If the MD5 value is the same to the value that received from the upgrade command, the firmware will be written to the internal flash area by the application programming technology IAP of MCU. This scheme is suitable for the firmware remote upgrade of all MCU that based on flash. It is proved to work steadily in several field experimentation and to meet satisfactorily the design request. The remote upgrade system is advanced, safe and reliable.