基于Cortex-M3的车载无线视频服务器串口扩展设计

Design of Serial Port Expansion Based on Cortex-M3 in On-board Wireless Video Server

车载无线视频服务器系统中主芯片DM365通过串口和多个外部模块进行通信,而DM365只有两个串口。采用TI公司基于Cortex-M3内核的微控制器LM3S1538设计一个对DM365串口进行扩展的嵌入式系统,利用μC/OS-Ⅱ嵌入式实时操作系统对DM365与系统外部各个模块之间的通信进行管理。介绍了串口扩展的硬件设计方案,详细地阐述了软件设计方法,包括μC/OS-Ⅱ操作系统的移植和应用程序的设计。本设计可以稳定地工作在车载无线视频服务器系统中,很好地解决了该系统中串口不足的问题。

In the on-board wireless video server system, the core MCU DM365 communicates with several other modules via serial port, but DM365 has only two serial ports. An embedded system for DM365 serial port expansion is designed by using the Cortex-M3 based MCU LM3S1538 of TI. The real- time embedded operating system μC/OS-Ⅱ is used to manage the communications between DM365 and the peripheral modules. In this paper, the serial port expansion circuit is introduced, and the software design including the μC/OS-Ⅱ transplantation and the application procedure design is recommended in detail. The design can work stably in the on-board wireless video server, it is a good solution to the lack of serial ports in this system.