Atmel SAM9X25, Manual

Page: 61 / 1145

61
11054A–ATARM–27-Jul-11
SAM9X25
61
11054A–ATARM–27-Jul-11
SAM9X25
NAND Flash Specific Header Detection
This is the first method used to determine NAND Flash parameters. After Initialization and Reset
command, the Boot Program reads the first page without ECC check, to determine if the NAND
parameter header is present. The header is made of 52 times the same 32-bit word (for redun-
dancy reasons) which must contain NAND and PMECC parameters used to correctly perform
the read of the rest of the data in the NAND. This 32-bit word is described below:
• usePmecc: Use PMECC
0 = Do not use PMECC to detect and correct the data.
1 = Use PMECC to detect and correct the data.
• nbSectorPerPage: Number of sectors per page
• spareSize: Size of the spare zone in bytes
• eccBitReq: Number of ECC bits required
• sectorSize: Size of the ECC sector
0 = for 512 bytes.
1 = for 1024 bytes per sector.
Other value for future use.
• eccOffset: Offset of the first ECC byte in the spare zone
A value below 2 is not allowed and will be considered as 2.
• key: value 0xC must be written here to validate the content of the whole word.
If the header is valid, the Boot Program will continue with the detection of valid code.
31 30 29 28 27 26 25 24
key
-
eccOffset
23 22 21 20 19 18 17 16
eccOffset sectorSize
15 14 13 12 11 10 9 8
eccBitReq spareSize
7 6 5 4 3 2 1 0
spareSize nbSectorPerPage usePmecc