Jai,
Here's my thoughts from past experience. Due to the nature of the way that NAND works, I'm assuming you're using parallel NAND rather than SPIFI, address & data lines are shared I/O's so would likely cause much worse problems than it sounds like you are having.
To me the more likely cause would be an error in addressing. If you are miscalculating under certain conditions or accidentally wrapping around the part and overwriting an already written area you'll end up with a logical AND between the data that was there and the new data.
Hope that helps. Good luck.
Gary Loomis
Advisory Firmware Engineer
P 651 789 7349
Global Traffic Technologies, LLC • 7800 Third Street North • St. Paul, Minnesota 55128-5441
fax 651-789-7334 •
www.gtt.com
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> 1. some bit changed from '1' to '0' in one page (Jia Guo)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 28 Jul 2017 20:09:01 +0800 (CST)
> From: "Jia Guo" <yunyuaner@163.com>
> To: yaffs <yaffs@stoneboat.aleph1.co.uk>, duweiA
> <duweiA@mail.maipu.com>, handong
> <handong@mail.maipu.com>
> Subject: [Yaffs] some bit changed from '1' to '0' in one page
> Message-ID:
> <355f4a56.76.15d89199365.Coremail.yunyuaner@163.com>
> Content-Type: text/plain; charset="gbk"
>
> Hi,
>
> I'm doing a serial of test on our target board, under linux and
> using yaffs2 as rootfs. The test includes memory read/write,
> ethernet packet send/receive and some yaffs2 filesystem read
> and write. Our firmware image is stored as a file under yaffs2.
> After doing the recursive test for about 10 hours under 50C
> temperature, serveral bytes in firmware image has changed,
> such as: change from BF 2C to B7 24, or from E4 8D E5 12 to
> E0 89 E1 10 and so on, all the changes happened at one of the
> bits from bits[0-3] in a byte, changed from '1' to '0'. The
> changed bytes are all in one nand page, and I've made sure
> that the ECC bytes of that page are changed too, and the ECC
> is generated by hareware. As far as I know, both GC/Wear
> Leveling and Log recording can cause yaffs2 write. Are there
> some related issue filed before? Or is it looks like a hardware
> related issue such as signal integrity?
>
> Thanks Jia
>
>
>
>
>
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