| Along with the widely application and popularization of high performance, low power loss MC9S12 series Micro-Controller Unit, which newly promoted by Freescale semiconductor Inc., the paper analyzed working principles of In System Programming of MC9S12 series Micro-Controller Unit in detail, studied the Background Debug Mode thoroughly, and compared two kinds of asynchronous communication, in order to make electronic engineers use the MC9S12 series MCU in their applications more conveniently and to solve the problem of program upgrading. Then the paper provided the developing plan of Procedure Downloads System for MC9S12 series MCU, the design and implementation from the aspects of hardware and software. By comprehending how MC9S12 MCU works and the internal mechanism of Flash, the monitor procedure has been realized successfully. On the basis of analysing the operating principle of MC9S12 BDM module deeply, solving the problem of communication of MCU's BDM module, the downloading of monitor procedure has been implemented. Enacting a mature control strategy and communication protocols, the Downloader which is matched with the monitor procedure has been designed and developed. With the help of monitor procedure and Downloader, the upgrading of objects' procedure could be solved. |
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