Nand Read Sector Procedure; Pins Used For Nand Boot - Texas Instruments TMS320C6A816 Series Technical Reference Manual

Memory Booting

21.7.3.1 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
Figure 21-14 shows the read sector routine for NAND devices. The ROM Code uses normal read
(command 00h 30h) for reading NAND page data.
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.
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.
21.7.3.2 Pins Used
The list of pins that are configured by the ROM in case of NAND boot mode are in
that all the pins might not be driven at boot time.
Signal name
cs0
advn_ale
oen_ren
be0n_cle
wen
wait
clk
ad0 - ad15
2010 ROM Code Memory and Peripheral Booting
Preliminary
Figure 21-14. NAND Read Sector Procedure
Read Sector
Yes
Is this Block
Invalid
No
Read 512 Bytes
Sector
GPMC ECC
Yes
?
NAND ECC
No
Success
Figure 21-15
Table 21-17. Pins Used for NAND Boot
© 2011, Texas Instruments Incorporated
Failed
Correct
Error
Success
Failed
and Figure 21-16 show the mapping of ECC data
Pin used
gpmc_cs0
gpmc_advn_ale
gpmc_oen_ren
gpmc_be0n_cle
gpmc_wen
gpmc_wait
gpmc_clk
gpmc_ad0 - gpmc_ad15
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Table 21-17. Note
SPRUGX9 – 15 April 2011
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