嵌入式cortex-M3开发板开发：以五向键控制led灯柱的闪烁，并将信息显示在4位米字管殇，同时通过uart上传。当有键按下时，蜂鸣器以0.2s周期鸣响，没有键按下时，蜂鸣器不响。-Embedded cortex-M3 development board development: the five key control led to a lamppost flashing, and the information is displayed in 4 m word pipe War, thro