Preliminary
Architecture
www.ti.com
5.2.4.12.3.3 Supported NAND Page Mappings and ECC Schemes
The following rules apply throughout the entire mapping description:
•
Main data area (sectors) size is hardcoded to 512 bytes.
•
Spare area size is programmable.
•
All page sections (of main area data bytes, protected spare bytes, unprotected spare bytes, and
ECC) are defined as explained in
Each one of the following sections shows a NAND page mapping example (per-sector spare mappings,
pooled spare mapping, per-sector spare mapping, with ECC separated at the end of the page).
In the mapping diagrams, sections that belong to the same BCH codeword have the same color (blue
or green); unprotected sections are not covered (orange) by the BCH scheme.
Below each mapping diagram, a write (encoding) and read (decoding: syndrome generation) sequence
is given, with the number of the active buffers at each point in time (yellow). In the inactive zones
(grey), no computing is taking place but the data counter is still active.
In
to
, tables on the left summarize the mode, size0, size1 parameters to
program for respectively write and read processing of a page, with the given mapping, where:
•
P is the size of spare byte section Protected by the ECC (in nibbles)
•
U is the size of spare byte section Unprotected by the ECC (in nibbles)
•
E is the size of the ECC itself (in nibbles)
•
S is the number of Sectors per page (2 in the current diagrams)
Each time the processing of a BCH block is complete (ECC calculation for write/encoding, syndrome
generation for read/decoding, indicated by red arrows), the update pointer is pulsed. Note that the
processing for block 0 can be the first or the last to complete, depending on the NAND page mapping
and operation (read or write). All examples show a page size of spares, that is, S = 2 sectors
of 512 bytes. The same principles can be extended to larger pages by adding more sectors.
The actual BCH codeword size is used during the error location work to restrict the search range: by
definition, errors can only happen in the codeword that was actually written to the NAND, and not in the
mathematical codeword of n = 2 - 1 = 8191 bits. That codeword (higher-order bits) is all-zero and
implicit during computations.
The actual BCH codeword size depends on the mode, on the programmed sizes and on the sector
number (all sizes in nibbles):
•
Spares mapped and protected per sector (
: see M1-M2-M3-M9-M10):
–
all sectors: (512) + P + E
•
Spares pooled and protected by sector 0 (
: see M5-M6):
–
sector 0 codeword: (512) + P + E
–
other sectors: (512) + E
•
Unprotected spares (
: see M4-M7-M8-M11-M12):
–
all codewords (512) + E
622
General-Purpose Memory Controller (GPMC)
SPRUGX9 – 15 April 2011
© 2011, Texas Instruments Incorporated
Содержание TMS320C6A816 Series
Страница 2: ...Preliminary 2 SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...
Страница 92: ...92 Read This First SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...
Страница 1122: ...1122 Multichannel Audio Serial Port McASP SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...
Страница 1562: ...1562 Real Time Clock RTC SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...
Страница 1658: ...1658 Timers SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...
Страница 1750: ...1750 UART IrDA CIR Module SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...
Страница 1984: ...1984 Universal Serial Bus USB SPRUGX9 15 April 2011 Submit Documentation Feedback 2011 Texas Instruments Incorporated...