MPLAB® Xpress Evaluation Board - General Knowledge
- The MPLAB® Xpress Evaluation Board should connect to the PC as a USB Flash drive (no drivers are needed) and should be seen as a hard drive. The PIC18LF25K50 on the Xpress board is not implementing a full MSD application (mass storage) but it only emulates one.
- The file format is fixed and the contents of the drive are fixed as well. The format of the board is MS-DOS (FAT). This should be the default format for Mac® computers (Maverick, Yosemite, El Capitan), Linux® boxes (Ubuntu 14/15/16) and Windows® machines (7/8/10) and it's NOT meant to be re-formatted.
- When a file is written to the drive, the data is NOT stored in flash or any other media but immediately decoded and used to program the target device. The host operating system though, is assuming a proper write operation is taking place and it keeps an image of the resulting file in its own cache (RAM). When the Xpress is disconnected (or the reset button is pressed) the host clears the cache so when the reset button is released (or the drive reconnected) the file seems to have disappeared (as it was never there in the first place).