通过串行口加载HEX程序文件，转换成BIN格式并保存在片外RAM中；加载完毕后蜂鸣器鸣叫，并等待按下K4；K4按下后，跳转到RAM去执行程序。-Through the serial port to load HEX file, converted to BIN format and stored in the RAM chip in loaded after the call buzzer and wait for press K4