DOSonChip to VINCULUM 2 usb

We have at present a PCB that uses a DOSonChip unit that we use to store information to a microMC memory card. This is proving to be unpopular so we need to convert this to a USB memory stick instead. The work will involve redesign of the PCB to replace the Dosonchip with USB and also the a relevant software to drive this. The existing file writing code should work seamlessly with the new USB interface. All work to be done in C using AVR studio. We will supply existing design and hardware and will require working and tested prototype in return. The code should be clean , well commented and bug free. The USB unit we are using is called VNC2 - Vinculum-II Programmable USB 2.0 Host Several functions will need to be implemented as follows FRESULT f_mount (BYTE, FATFS*); /* Mount/Unmount a logical drive */ FRESULT f_open (FIL*, const char*, BYTE); /* Open or create a file */ FRESULT f_read (FIL*, void*, UINT, UINT*); /* Read data from a file */ FRESULT f_write (FIL*, const void*, UINT, UINT*); /* Write data to a file */ FRESULT f_lseek (FIL*, DWORD); /* Move file pointer of a file object */ FRESULT f_close (FIL*); /* Close an open file object */ FRESULT f_opendir (DIR*, const char*); /* Open an existing directory */ FRESULT f_readdir (DIR*, FILINFO*); /* Read a directory item */ FRESULT f_stat (const char*, FILINFO*); /* Get file status */ FRESULT f_getfree (const char*, DWORD*, FATFS**); /* Get number of free clusters on the drive */ FRESULT f_truncate (FIL*); /* Truncate file */ FRESULT f_sync (FIL*); /* Flush cached data of a writing file */ FRESULT f_unlink (const char*); /* Delete an existing file or directory */ FRESULT f_mkdir (const char*); /* Create a new directory */ FRESULT f_chmod (const char*, BYTE, BYTE); /* Change file/dir attriburte */ FRESULT f_utime (const char*, const FILINFO*); /* Change file/dir timestamp */ FRESULT f_rename (const char*, const char*); /* Rename/Move a file or directory */ FRESULT f_mkfs (BYTE, BYTE, WORD);