对SPI flash ，SST25VF016B进行快速读写，采用软件模拟SPI总线的SPI0模式。-On the SPI flash, SST25VF016B fast read and write, using software to simulate the SPI bus SPI0 mode.

此例程将板子上的SST25VF016B虚拟为2M BYTES的U盘，可以通过PC用USB接口访问磁盘-This routine will be on board for the 2M BYTES SST25VF016B virtual U-disk, you can use the USB interface to access the disk PC