1.change the tick base on the board/Kconfig
2.The SD card and FLASH can be mounted to the specified directory of romFS at the same time,and SD card or flash can be used independently
3.Avoid the SD card and Flash mounting sequence. If the Flash mounts the SD card to a specific directory, ensure that the SD card is mounted first
1.fix some Kconfig file
2.add tensorflow-lite-for-mcu in knowing file
3.add mnist application,note the application cannot be used with RAM less than 500K.
4.the version need to separate application and OS(rtt),later by using add transform layer to solve it.