Read Invalid Blocks
Information
Invalid Block
Information
0xFF (or 0xFFFF for
16-bit devices)
¹
Yes
Read 1
st
nd
and 2
page spare
sectors
Set Invalid Block Flag
No
Clear Invalid Block Flag
For first
4 block
s
Functional Description
Bad Block Verification
Invalid blocks are blocks which contain invalid bits whose reliability cannot be guaranteed by the
manufacturer. Those bits are identified in the factory or during the programming and reported in the initial
invalid block information located in the spare area on the 1
st
and 2
nd
page of each block. Since the ROM
Code is looking for an image in the first four blocks, it must detect block validity status of these blocks.
Blocks which are detected as invalid are not accessed later on. Blocks validity status is coded in the spare
areas of the first two pages of a block (first byte equal to FFh in 1
st
and 2
nd
pages for an 8 bits device / first
word equal to FFFFh in 1
st
and 2
nd
page for a 16bits device).
depicts the invalid block detection routine. The routine consists in reading spare areas and
checking validity data pattern.
Figure 26-13. NAND Invalid Blocks Detection
26.1.7.4.2.1 NAND Read Sector Procedure
The ROM Code reads data from NAND devices in 512 bytes sectors. The read function fails in two cases:
•
The accessed sector is within a block marked as invalid
•
The accessed sector contains an error which cannot be corrected with ECC
shows the read sector routine for NAND devices. The ROM Code uses normal read
(command 00h 30h) for reading NAND page data.
4125
SPRUH73H – October 2011 – Revised April 2013
Initialization
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