Is this block
invalid
Read Sector
GPMC ECC
?
NAND ECC
Success Failed
No
Yes
No
Yes
Read 512 bytes sector
Correct Error
Success
Failed
Functional Description
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Figure 26-14. NAND Read Sector Procedure
Page data can contain errors due to memory alteration. The ROM Code uses an ECC correction algorithm
to detect and possibly correct those errors. The ECC algorithm used is BCH with capability for correcting
8b or 16b errors per sector. The BCH data is automatically calculated by the GPMC on reading each 512
bytes sector. The computed ECC is compared against ECC stored in the spare area for the corresponding
page. Depending on the page size, the amount of ECC data bytes stored in the corresponding spare area
is different. Figure 26-15 and Figure 26-16 show the mapping of ECC data inside the spare area for
respectively 2KB-page and 4KB- page devices. If both ECC data are equal then the Read Sector function
returns the read 512 bytes sector without error. Otherwise the ROM Code tries to correct error(s) in the
corresponding sector (this procedure is assisted by the ELM hardware) and returns the data if successful.
If errors are uncorrectable, the function returns with FAIL.
4126
Initialization SPRUH73H–October 2011–Revised April 2013
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