The on-board debugger implements a highly optimized variant of the FAT12 file system having several limitations, partly due to the nature of FAT12 itself and optimizations made to fulfill its purpose for its embedded application.
The Curiosity Nano USB device is USB Chapter 9-compliant as a mass storage device but does not, in any way, fulfill the expectations of a general purpose mass storage device. This behavior is intentional.
When using the Windows operating system, the on-board debugger enumerates as a Curiosity Nano USB Device found in the disk drives section of the device manager. The CURIOSITY drive appears in the file manager and claims the following available drive letter in the system.
The CURIOSITY drive contains approximately one MB of free space and does not reflect the target device’s Flash size. When programming an Intel® HEX file, the binary data are encoded in ASCII with metadata providing a large overhead, so 1 MB is a trivially chosen value for disk size.
It is not possible to format the CURIOSITY drive. The filename may appear in the disk directory listing when programming a file to the target, which is merely the operating system’s view of the directory that, in reality, has not been updated. It is not possible to read out the file contents. Removing and replugging the board will return the file system to its original state, but the target will still contain the previously programmed application.
Copy a text file starting with “CMD:ERASE” onto the disk to erase the
target device.
By default, the CURIOSITY drive contains several read-only files for generating icons as well as reporting status and linking to further information:
AUTORUN.ICO – icon file
for the Microchip logoAUTORUN.INF – system
file required for Windows Explorer to show the icon fileKIT-INFO.HTM – redirect
to the development board websiteKIT-INFO.TXT – a text
file containing details about the board’s debugger firmware version, board name, USB
serial number, device, and drag-and-drop supportSTATUS.TXT – a text
file containing the programming status of the boardSTATUS.TXT is dynamically updated by the on-board debugger. The
contents may be cached by the OS and, therefore, not reflecting the correct status.