MPFS2

The MPFS2 file system module provides a light-weight read-only file system that can be stored in external EEPROM, external serial Flash, or internal Flash program memory. This file system serves as the basis for the HTTP2 web server module, but is also used by the SNMP module and is available to other applications that require basic read-only storage capabilities. 

The MPFS2 module includes an MPFS2 Utility that runs on your PC. This program builds MPFS2 images in various formats for use in the supported storage mediums. More information is available in the MPFS2 Utility section.

For external storage, the MPFS2 file system supports Microchip 25LCxxx EEPROM parts for densities up to 1Mbit. SST 25VFxxxB serial Flash parts are also supported for densities up to 32Mbit. 

To use external EEPROM storage, ensure that the configuration macro MPFS_USE_EEPROM is defined in TCPIPConfig.h. If you are using a 1Mbit part (25LC1024), also be sure to define USE_EEPROM_25LC1024 to enable the 24-bit device addressing used by that part. For external serial Flash, define MFPS_USE_SPI_FLASH instead of the EEPROM macros. 

Images stored externally are uploaded via HTTP. This can be accomplished using the MPFS2 Utility, or can be accessed directly from a browser. Uploading files directly is described in the MPFS2 Utility documentation. Uploading images via HTTP can be accomplished as described in the Getting Started section. 

When storing images externally, space can be reserved for separate application use. The configuration macro MPFS_RESERVE_BLOCK controls the size of this space. The specified number of bytes will be reserved at the beginning address of the storage device (0x000000). When using serial Flash, this address must be a multiple of the flash sector size (4096 bytes).

When storing images in internal Flash program memory, new images cannot be uploaded at run time. Instead, the image is compiled in as part of your project in the MPLAB IDE. To select this storage option comment out the configuration macro MPFS_USE_EEPROM in TCPIPConfig.h, then ensure that the image file generated by the MPFS2 Utility is included in the MPLAB project.

MPFS2 defines a fixed number of files that can be opened simultaneously. The configuration parameter MAX_MPFS_HANDLES controls how many files can be opened at once. If this resource is depleted, no new files can be opened until MPFSClose is called for an existing handle. The HTTP2 web server expects to be able to use at least two handles for each connection, plus one extra. Additional handles should be allocated if other modules will be accessing the file system as well.