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Allwinner A13

November 5th, 2018, 18:22

Does anybody has BCH parameters for Allwinner A13 nand flash controller ?
It's for Reread a STorex Ezee tablet nand flash (H27UCG8T2ATR-BC)
I have found the XOR key. But I can't found the ECC parameters

Re: Allwinner A13

November 7th, 2018, 1:37

Yes, here it is. Should be in DB, I sent it some time ago to developers. They do not add it?
(512 Bytes) Downloaded 252 times

Re: Allwinner A13

November 7th, 2018, 13:34

In unknown cases of ECC its worth to use codeword analysis tool. It's very easy and effective to use, Connect BCH element to physical image and as Payload you set assumed range of data area and eventually spare area if it exist, in Parity - range of ECC area (positions counted from 0). In this case it little more complicated because DA and Spare aren't in row. You can use offset to skip bytes between them (you have to shrink page size in codeword analyser settings as well). Polynomial is dec/hex representation of binary generation polynomial for parity bits e.g. 369d is binary 1 0111 0001 and polynomial for it is:

x^8 + x^6 + x^5+ x^4 + 1(x^0)

Degree is the value of highest power.

To choose correct degree for analyse add total length of payload and parity bytes for codeword ( in your case based on Michal's file it's 1028+50 = 1078 bytes and it's 8624 bits). 8624<16384 ( 2^14) so correct degree is 14.

You can also use predefined specific polynomial as well.
Result you receive will be in range 1-64 and it's ratio correctable codewords to tested codewrods (higher is better).

Re: Allwinner A13

November 27th, 2018, 2:49

Thanks, I will test.

Re: Allwinner A13

December 5th, 2018, 17:26

I don't find,
- data area 8192 bytes, only data (when uXored)
- spare area 640 bytes (with the last 48 at xFF)
With bitmap viewer no trace for header, LBN and LPN.
perhaps the A13 controller use tables at the beginning of the chip memory ?
Allwiner specifications about NFC
(5.66 MiB) Downloaded 229 times
data/spare area on unXored bitmap

Re: Allwinner A13

December 6th, 2018, 11:07

The BCH codeword from Michał was for ECC area equal 50 bytes, the one you have is 70. Also Allwinner xor spare and ECC areas as well and from the point I see you applied it only for DA. Header, LBN and LPN are in first and second spare area.The correct page structure will be: DA 8192 (SA 4 ECC 70)*8.
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