SPI Sector Layout

The SPI Sector Layout description file, FS_SPI_FlashDev.h, specifies the memory map of a SPI Flash device. Every device has its own description file, which is located in the folder \ARM\RL\FlashFS\Flash.

To generate a description file, copy the flash sector layout information from the Flash Device datasheet, specify a sector size in bytes, and a sector base address relative to an SPI Flash Device. The Macro DSB converts this information into the RL-FlashFS compatible sector description.

To improve the RL-FlashFS performance, the sector information is stored as a table in the code. The RL-FlashFS scans this table when accessing files from the SPI Flash device.

The following example shows a Flash sector layout configuration for the Intel SPI Flash device 25F160S33 with 2MByte memory:

#define SPI_FLASH_DEVICE                              \ 
  DSB(0x10000, 0x000000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x010000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x020000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x030000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x040000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x050000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x060000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x070000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x080000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x090000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x0A0000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x0B0000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x0C0000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x0D0000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x0E0000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x0F0000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x100000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x110000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x120000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x130000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x140000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x150000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x160000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x170000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x180000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x190000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x1A0000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x1B0000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x1C0000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x1D0000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x1E0000),     /* Sector Size 64kB */ \ 
  DSB(0x10000, 0x1F0000),     /* Sector Size 64kB */ \ 

#define SF_NSECT    32

It is not optimal to define lots of small sectors (256 bytes or smaller). A more optimal solution for the RL-FlashFS is to join several physical sectors into bigger virtual sectors. In this case, the function EraseSector must be modified to erase a virtual sector, not a single physical sector.