Rabbit 2000 - Page 39

Designer’s Handbook 37
with it. You will probably be required to copy the function from flash to a RAM buffer in
the flash initialization sequence.
The field writeMode specifies the method that particular flash device uses to write data.
Currently, only two common modes are defined: “sector-writing” mode, as used by the
SST SST29 and Atmel AT2 9 series (writeMode=1); and “byte-writing” mode, as used
by the Mosel/Vitelic V29 series (writeMode=2). All other values of writeMode are
currently undefined, although they may be defined by Z-World as new flash devices are
used.
The required actions of these functions are listed below:
_InitFlashDriver
This function is called from the BIOS. A bitmap of quadrants mapped to flash (0x01,
0x02, 0x04, 0x08 correspond to the 1st-4th quadrants) is passed to it in HL. This func-
tion needs to perform the following actions:
1. Load _FlashInfo.XPC with the proper XPC value to access flash
memory address 00000h via XMEM address E000h. The quadrant num-
ber for the start of flash memory is passed to the function in HL and can be
used to determine the XPC value, if desired. For example, if your flash is
located in memory quadrant 2 then the physical address of the first flash
memory location is 80000h. 80000h - E000h = 72000h, so the
value placed into _FlashInfo.XPC should be 72h.
3. Load _FlashInfo.sectorSize with the flash sector size in bytes.
4. Load _FlashInfo.numSectors with the number of sectors on the
flash.
5. _FlashInfo.writeFlashPtr should be loaded with the memory
location in RAM of the function that will perform that action. The function
will need to be copied from flash to RAM at this time as well. The
eraseChipPtr point should be loaded as well with the address of the
appropriate function (also in RAM).
6. This function should return zero if successful, or -1 if an error occurs.