本代bootloader通过usb下载代码首先存放在sdram中，然后拷贝到dataflash中并加载。本代码经过反复测试，准确无误，绝对可靠。环境IAR-This generation through usb download bootloader code stored in the sdram of the first, and then copied to and loaded in dataflash. After repeated testing of the code, accur