SAM3X8E Atmel Corporation, SAM3X8E Datasheet - Page 475

• Manufacturer Part Number: SAM3X8E
• Manufacturer: Atmel Corporation

26.17.1
26.17.2
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12
Write Access
Read Access
mend to utilize either 1 ECC per 256 bytes of data, 1 ECC per 512 bytes of data or 1 ECC for all
of the page.
The only configurations required for ECC are the NAND Flash or the SmartMedia page size
(528/2112/4224) and the type of correction wanted (1 ECC for all the page/1 ECC per 256 bytes
of data /1 ECC per 512 bytes of data). Page size is configured setting the PAGESIZE field in the
ECC Mode Register (ECC_MR). Type of correction is configured setting the TYPCORRECT
field in the ECC Mode Register (ECC_MR).
Note that there is a limitation when using 16-bit NAND Flash: only 1 ECC for all of page is possi-
ble. For 8-bit NAND Flash there is no limitation.
ECC is automatically computed as soon as a read (00h)/write (80h) command to the NAND
Flash or the SmartMedia is detected. Read and write access must start at a page boundary.
ECC results are available as soon as the counter reaches the end of the main area. Values in
the ECC Parity Registers (ECC_PR0 to ECC_PR15) are then valid and locked until a new start
condition occurs (read/write command followed by address cycles).
Once the Flash memory page is written, the computed ECC codes are available in the ECC Par-
ity (ECC_PR0 to ECC_PR15) registers. The ECC code values must be written by the software
application in the extra area used for redundancy. The number of write accesses in the extra
area is a function of the value of the type of correction field. For example, for 1 ECC per 256
bytes of data for a page of 512 bytes, only the values of ECC_PR0 and ECC_PR1 must be writ-
ten by the software application. Other registers are meaningless.
After reading the whole data in the main area, the application must perform read accesses to the
extra area where ECC code has been previously stored. Error detection is automatically per-
formed by the ECC controller. Please note that it is mandatory to read consecutively the entire
main area and the locations where Parity and NParity values have been previously stored to let
the ECC controller perform error detection.
The application can check the ECC Status Registers (ECC_SR1/ECC_SR2) for any detected
errors. It is up to the application to correct any detected error. ECC computation can detect four
different circumstances:
• No error: XOR between the ECC computation and the ECC code stored at the end of the
• Recoverable error: Only the RECERR flags in the ECC Status registers
• ECC error: The ECCERR flag in the ECC Status Registers (ECC_SR1/ECC_SR2) is set. An
NAND Flash or SmartMedia page is equal to 0. No error flags in the ECC Status Registers
(ECC_SR1/ECC_SR2).
(ECC_SR1/ECC_SR2) are set. The corrupted word offset in the read page is defined by the
WORDADDR field in the ECC Parity Registers (ECC_PR0 to ECC_PR15). The corrupted bit
position in the concerned word is defined in the BITADDR field in the ECC Parity Registers
(ECC_PR0 to ECC_PR15).
error has been detected in the ECC code stored in the Flash memory. The position of the
corrupted bit can be found by the application performing an XOR between the Parity and the
NParity contained in the ECC code stored in the Flash memory.
SAM3X/A
SAM3X/A
475
475