EEPROM.txt

Capes and Hats on a Beaglebone or Raspberry Pi can have an onboard 24c256
eeprom on their primary i2c bus to provide additional configuration about
the cape/hat to the FPP system utilities.   On the Pi, the default is on
the i2c-1 bus.   On the Beagle, the default is i2c-2, but it will fall back
to looksin at the i2c-1 bus if no eeprom is found on i2c-1.

The format of the contents of the eeprom are divided into two parts.  The
first part is a header which contains static informmation about the board.

Bytes
0-5      EEPROM format identifier string, null terminated.  Currently "FPP02"
6-31     Cape name as null terminated string (26 bytes)
32-41    Cape version as null terminated string (10 bytes)
42-57    Cape serial number as null terminated string (16 bytes)


The second part of the content is a bunch of variable length records repeating:
0-5      LENGTH (as a string).  If the string "0", end of eeprom data
6-7      Code representing the type of record.  Number between 0-99 as a string
         The 2 bytes for the code is NOT included in LENGTH

If code is less than 50, the code is immediately followed by:
8-71     Filename as null terminated string.  ex:  "tmp/cape-info.json" (64 char)
         The 64bytes for the filename is NOT included in the LENGTH

If code is 0, the filename is followed by LENGTH bytes of data to be written
into the file.

If code is 1, the filename is followed by LENGTH bytes of data to be written
into the file, and then unzip is called on the file.

If code is 2, the filename is followed by LENGTH bytes of data to be written
into the file, and then "tar -xzf" is called on the file.

Codes above 90 are current reserved for digital signature verification codes
and information required to process and verify digital signatures.  For
basic use of eeprom, these are not required.


Since the 24c256 is limitted to 32K and reading/writing is relatively slow,
people are encouraged to package multiple files into either zip or tar.gz
files and use the 1 or 2 codes to add them to the eeprom.