The disk_write writes sector(s) to the disk.
DRESULT disk_write ( BYTE drv, /* [IN] Physical drive number */ const BYTE* buff, /* [IN] Write data (may be non aligned) */ DWORD sector, /* [IN] Sector number to write */ BYTE count /* [IN] Number of sectors to write */ );
This function is not required in read only configuration. The specified memory address is not that always aligned to word boundary because the type of pointer is defined as BYTE. For more information, read description in disk_read function.